Nº de abstracts = 140

Modifcado em 23 Fevereiro 2012

Effects of 21 days of intensified training on markers of overtraining.

Slivka DR, Hailes WS, Cuddy JS, Ruby BC : Journal of strength and conditioning research / National Strength & Conditioning Association, 2010 24(10):2604-12. Montana Center for Work Physiology and Exercise Metabolism, University of Montana, Missoula, Montana, USA.

The purpose of this study was to impose a period of quantifiable intensified training to determine if commonly used diagnostic markers of overtraining parallel changes in physical performance and thus overtraining status. Eight trained male cyclists (24 ± 1 years, 71 ± 3 kg, VO2peak = 4.5 ± 0.1·L·min?¹) performed 21 days (3,211 km) of intensified training in the field where volume and intensity were increased over normal training. Salivary IgA, testosterone, and cortisol, 1-hour time trial performance, heart rate response, and profile of mood states (POMS) were collected and analyzed throughout the 21-day training period. The POMS category vigor declined from day 1 to day 4 and remained lower throughout (p < 0.05). There were no other statistical changes in overtraining parameters. However, individuals who demonstrated 2 or more symptoms of overtraining at any point throughout the 21 days were considered symptomatic and had a lower (p < 0.05) VO2peak (4.2 ± 0.1·vs. 4.7 ± 0.1 L·min?¹) and lower (p 0.05). These data demonstrate that markers of overtraining do not parallel a decrease in performance and should be interpreted with caution.

Effects of a concurrent strength and endurance training on running performance and running economy in recreational marathon runners.

Ferrauti A, Bergermann M, Fernandez-Fernandez J .: Journal of strength and conditioning research / National Strength & Conditioning Association, 2010, 24(10):2770-8. Department of Coaching Science, Faculty of Sports Science, Ruhr-University, Bochum, Germany.

The purpose of this study was to investigate the effects of a concurrent strength and endurance training program on running performance and running economy of middle-aged runners during their marathon preparation. Twenty-two (8 women and 14 men) recreational runners (mean ± SD: age 40.0 ± 11.7 years; body mass index 22.6 ± 2.1 kg·m?²) were separated into 2 groups (n = 11; combined endurance running and strength training program [ES]: 9 men, 2 women and endurance running [E]: 7 men, and 4 women). Both completed an 8-week intervention period that consisted of either endurance training (E: 276 ± 108 minute running per week) or a combined endurance and strength training program (ES: 240 ± 121-minute running plus 2 strength training sessions per week [120 minutes]). Strength training was focused on trunk (strength endurance program) and leg muscles (high-intensity program). Before and after the intervention, subjects completed an incremental treadmill run and maximal isometric strength tests. The initial values for VO2peak (ES: 52.0 ± 6.1 vs. E: 51.1 ± 7.5 ml·kg?¹·min?¹) and anaerobic threshold (ES: 3.5 ± 0.4 vs. E: 3.4 ± 0.5 m·s?¹) were identical in both groups. A significant time × intervention effect was found for maximal isometric force of knee extension (ES: from 4.6 ± 1.4 to 6.2 ± 1.0 N·kg?¹, p < 0.01), whereas no changes in body mass occurred. No significant differences between the groups and no significant interaction (time × intervention) were found for VO2 (absolute and relative to VO2peak) at defined marathon running velocities (2.4 and 2.8 m·s?¹) and submaximal blood lactate thresholds (2.0, 3.0, and 4.0 mmol·L?¹). Stride length and stride frequency also remained unchanged. The results suggest no benefits of an 8-week concurrent strength training for running economy and coordination of recreational marathon runners despite a clear improvement in leg strength, maybe because of an insufficient sample size or a short intervention period.

Metabolic factors limiting performance in marathon runners.

Rapoport BI.: PLoS computational biology, 2010 (10):e1000960. States M.D.- Ph.D. Program, Harvard Medical School, Boston, Massachusetts, United States of America.

Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers), more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as 'hitting the wall'), and thousands drop out before reaching the finish lines (approximately 1-2% of those who start). Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making 'hitting the wall' seem inevitable), or implied that maximal glycogen loading is required in order to complete a marathon without 'hitting the wall.' The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity) of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding 'the wall.' The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon.

Effects of dynamic stretching on energy cost and running endurance performance in trained male runners. Zourdos MC, Wilson JM, Sommer BA, Lee SR, Park YM, Henning PC, Panton LB, Kim JS

26(2):335-41, 2012 Zourdos, MC, Wilson, JM, Sommer, BA, Lee, S-R, Park, Y-M, Henning, PC, Panton, LB, and Kim, J-S. Effects of dynamic stretching on energy cost and running endurance performance in trained male runners. J Strength Cond Res 26(2): 335-341, 2012-The purpose of this study was to examine the effects of dynamic stretching on running energy cost and endurance performance in trained male runners. Fourteen male runners performed both a 30-minute preload run at 65% &OV0312;O2max and a 30-minute time trial to assess running energy cost and performance, respectively. The subjects repeated both the trials after either 15 minutes of dynamic stretching (i.e., experimental condition) or quiet sitting (i.e., control condition) while the order was balanced between the subjects to avoid any order effect. The total calories expended were determined for the 30-minute preload run, whereas the distance covered was measured in the time trial. Average resting &OV0312;O2 increased significantly (p < 0.05) after dynamic stretching (prestretch: 6.2 ± 1.7 vs. poststretch: 8.4 ± 2.1 ml·kg·min) but not during the quiet-sitting condition. Caloric expenditure was significantly higher during the 30-minute preload run for the stretching (416.3 ± 44.9 kcal) compared with that during the quiet sitting (399.3 ± 50.4 kcal) (p < 0.05). There was no difference in the distance covered after quiet sitting (6.3 ± 1.1 km) compared with that for the stretching condition (6.1 ± 1.3 km). These findings suggest that dynamic stretching does not affect running endurance performance in trained male runners.

Effect of cold acclimatization on exercise economy in the cold. Muller MD, Kim CH, Bellar DM, Ryan EJ, Seo Y, Muller SM, Glickman EL.

112(2):795-800, 2012 We sought to determine if cold acclimatized men display higher economy (i.e. lower oxygen consumption at a given workload) during graded cycle ergometry in the cold (5°C). After completing a familiarization trial 1 week prior, five cold weather athletes (CWA) and eight physically active men (NON) underwent graded exercise tests to volitional fatigue in 5°C. The protocol always started at 60 W and increased by 20 W each minute. Oxygen consumption (VO(2)), respiration rate (RR), tidal volume (TV), and respiratory exchange ratio (RER) were determined via open circuit spirometry. Individuals were matched for body size and minutes of weekly physical activity. Repeated measures analyses of variance were conducted across time (workload) and cold acclimatization was entered as a between subjects factor. VO(2) peak was not different between groups but CWA had lower VO(2) at 60 and 240 W. CWA also had lower RR at 180 and 260 W as well as lower RER at 240 and 260 W. At submaximal workloads, cold acclimatized men have higher exercise economy than non-acclimatized men. This could have implications for those who work in this context.

Dry-Land Strength Training vs. Electrical Stimulation in Sprint Swimming Performance. Girold S, Jalab C, Bernard O, Carette P, Kemoun G, Dugué B.

26(2):497-505, 2012 Dry-land strength training vs. electrical stimulation in sprint swimming performance. J Strength Cond Res 26(2): 497-505, 2012-This study was undertaken to compare the effects of dry-land strength training vs. an electrical stimulation program on swimmers. Twenty-four national-level swimmers were randomly assigned to 3 groups: the dry-land strength training program (S), the electrical stimulation training program (ES), and the control (C) group. The training program lasted 4 weeks. The subjects were evaluated before the training, at the end of the training program, and 4 weeks later. The outcome values ascertained were peak torque during arm extension at different velocities (from -60 to 180°·s) using an isokinetic dynamometer and performance, stroke rate, and stroke length during a 50-m front crawl. A significant increase in swimming velocity and peak torque was observed for both S and ES at the end of the training and 4 weeks later. Stroke length increased in the S group but not in the ES group. However, no significant differences in swimming velocity between S and ES groups were observed. No significant changes occurred in the C group. Programs combining swimming training with dry-land strength or electrical stimulation programs led to a similar gain in sprint performance and were more efficient than swimming alone.

Differences in adaptations to 1 year of aerobic endurance training: individual patterns of nonresponse. Scharhag-Rosenberger F, Walitzek S, Kindermann W, Meyer T

22(1):113-8, 2012.Lacking responses to endurance training (ET) have been observed for several variables. However, detailed analyses of individuals' responses are scarce. To learn more about the variability of ET adaptations, patterns of response were analyzed for each subject in a 1-year ET study. Eighteen participants [42±5 years, body mass index: 24±3 kg/m(2) , maximal oxygen uptake (VO(2max) ): 38±5 mL/min/kg] completed a 1-year jogging/walking program on 3 days/week, 45 min/session at 60% heart rate (HR) reserve. VO(2max) , resting HR (rHR), exercise HR (eHR) and individual anaerobic threshold (IAT) were determined by treadmill and cycling ergometry respectively. Intraindividual coefficients of variation were extracted from the literature to distinguish random changes from training responses. Eight participants showed improvements in all variables. In 10 participants, one or two variables did not improve (VO(2max) , rHR, eHR and IAT remained unchanged in four, four, three and one cases, respectively). At least one variable improved in each subject. Data indicate that ET adaptations might be detected in each individual using multiple variables of different adaptation levels and intensity domains. Nonresponse seems to occur frequently and might affect all variables. Further studies should investigate whether nonresponders improve with altered training. Furthermore, associations between patterns of nonresponse and health benefits from ET are worth considering.

Cold water immersion recovery after simulated collision sport exercise. Pointon M, Duffield R

44(2):206-16, 2012 PURPOSE: This investigation examined the effects of cold water immersion (CWI) recovery after simulated collision sport exercise.

METHODS: Ten male rugby athletes performed three sessions consisting of a 2 × 30-min intermittent-sprint exercise (ISE) protocol with either tackling (T) or no tackling (CONT), followed by a 20-min CWI intervention (TCWI) or passive recovery (TPASS and CONT) in a randomized order. The ISE consisted of a 15-m sprint every minute separated by self-paced bouts of hard running, jogging, and walking for the remainder of the minute. Every sixth rotation, participants performed 5 × 10-m runs, receiving a shoulder-led tackle to the lower body on each effort. Sprint time and distance covered during ISE were recorded, with voluntary (maximal voluntary contraction; MVC) and evoked neuromuscular function (voluntary activation; VA), electromyogram (root mean square (RMS)), ratings of perceived muscle soreness (MS), capillary and venous blood markers for metabolites and muscle damage, respectively measured before and after exercise, immediately after recovery, and 2 and 24 h after recovery.

RESULTS: Total distance covered during exercise was significantly greater in CONT (P = 0.01), without differences between TPASS and TCWI (P > 0.05). TCWI resulted in increased MVC, VA, and RMS immediately after recovery (P < 0.05). M-wave amplitude and peak twitch were significantly increased after recovery and 2 h after recovery, respectively, in TCWI (P 0.05), lactate was significantly reduced after recovery compared with TPASS (P = 0.04). CWI also resulted in reduced MS 2 h after recovery compared with TPASS (P < 0.05).

CONCLUSIONS: The introduction of body contact reduces exercise performance, whereas the use of CWI results in a faster recovery of MVC, VA, and RMS and improves muscle contractile properties and perceptions of soreness after collision-based exercise.

Analysis of repeated high-intensity running performance in professional soccer. Carling C, Le Gall F, Dupont G

201202,

30(4):325-36 Abstract The aims of this study were twofold: (1) to characterize repeated high-intensity movement activity profiles of a professional soccer team in official match-play; and (2) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. High-intensity running performance (movement at velocities >19.8 km · h(-1) for a minimum of 1 s duration) was measured in 20 players using computerized time-motion analysis. Performance in 80 French League 1 matches was analysed. In addition, 12 of the 20 players performed a repeated-sprint test on a non-motorized treadmill consisting of six consecutive 6 s sprints separated by 20 s passive recovery intervals. In all players, most consecutive high-intensity actions in competition were performed after recovery durations =61 s, recovery activity separating these efforts was generally active in nature with the major part of this spent walking, and players performed 1.1 ± 1.1 repeated high-intensity bouts (a minimum of three consecutive high-intensity bouts with a mean recovery time =20 s separating efforts) per game. Players reporting lowest performance decrements in the repeated-sprint ability test performed more high-intensity actions interspersed by short recovery times (=20 s, P < 0.01 and =30 s, P < 0.05) compared with those with higher decrements. Across positional roles, central-midfielders performed more high-intensity actions separated by short recovery times (=20 s) and spent a larger proportion of time running at higher intensities during recovery periods, while fullbacks performed the most repeated high-intensity bouts (statistical differences across positional roles from P < 0.05 to P < 0.001). These findings have implications for repeated high-intensity testing and physical conditioning regimens.

Acute effect of whole-body vibration on power, one-repetition maximum, and muscle activation in power lifters. Rønnestad BR, Holden G, Samnøy LE, Paulsen G

201202 26(2):531-9,

Rønnestad, BR, Holden, G, Samnøy, LE, and Paulsen, G. Acute effect of whole-body vibration on power, one-repetition maximum, and muscle activation in power lifters. J Strength Cond Res 26(2): 531-539, 2012-The purpose of this study was to investigate the acute effect of whole-body vibration with a frequency of 50 Hz (WBV50Hz) on peak power in squat jump (SJ), 1 repetition maximum (1RM) in parallel squat, and electromyography (EMG) activity and compare them with no-vibration conditions in power lifters. Twelve national level male power lifters (age 24 ± 5 years, body mass 110 ± 24 kg, height 179 ± 7 cm) tested peak power in SJ and 1RM in parallel squat while they were randomly exposed to WBV50Hz or to no vibration. These tests were performed in a Smith Machine. Peak power output was higher while performed with a WBV50Hz compared with the no-WBV condition (p < 0.05). This increase in power output was accompanied by higher EMG starting values and EMG peak values of the investigated thigh muscles during WBV50Hz (p < 0.05). There was no difference between adding WBV50Hz and no-vibration conditions in 1RM parallel squat. In conclusion, the results of this study suggest that the application of WBV50Hz acutely increases peak power output during SJ in well strength trained individuals such as power lifters. This increase in power was accompanied by an increased EMG activity in the quadriceps muscles. However, in 1RM parallel squat, there was no difference between WBV50Hz and no-vibration conditions. Therefore, adding WBV50Hz has no acute additive effect on 1RM parallel squat in power lifters and, based on the present findings, may thus not be recommended in the training to improve 1RM in power lifters. However, WBV50Hz seems to have an acute additive effect on peak power output and may be used in well strength trained individuals for whom a high power output is important for performance.

The effects of adding different whole-body vibration frequencies to preconditioning exercise on subsequent sprint performance. Rønnestad BR, Ellefsen S

Journal of strength and conditioning research / National Strength & Conditioning Association 25(12):336-10, 2011 Dez Faculty of Human, Sports, and Social Sciences, Lillehammer University College, Lillehammer, Norway.

Rønnestad, BR and Ellefsen, S. The effects of adding different whole-body vibration frequencies to preconditioning exercise on subsequent sprint performance. J Strength Cond Res 25(12): 3306-3310, 2011-The phenomenon postactivation potentiation can possibly be used to acutely improve sprint performance. The purpose of this study was to investigate the effect of adding whole-body vibration (WBV) to body-loaded half-squats, performed as preconditioning activity to the 40-m sprint test. Nine male amateur soccer players performed 1 familiarization session and 6 separate test sessions. Each session included a standardized warm-up followed by 1 of the after preconditioning exercises: 30-seconds of half-squats with WBV at either 50 or 30 Hz or half-squats without WBV. The 40-m sprint was performed 1 minute after the preconditioning exercise. For each subject, each of the 3 protocols was repeated twice on separate days in a randomized order. Mean values were used in the statistical analysis. Performing the preconditioning exercise with WBV at a frequency of 50 Hz resulted in a superior 40-m sprint performance compared to preconditioning exercise without WBV (5.48 ± 0.19 vs. 5.52 ± 0.21 seconds, respectively, p < 0.05). There was no difference between preconditioning exercise with WBV at a frequency of 30 Hz and the no-WBV condition. In conclusion, preconditioning exercise performed with WBV at 50 Hz seems to enhance 40-m sprint performance in recreationally trained soccer players. The present findings suggest that coaches can incorporate such exercise into the warm-up to improve sprint performance or the quality of the sprint training.

The effect of a series of strength training sessions on 2000 m rowing ergometer performance and muscle function. Gee TI, French DN, Howatson G, Gibbon K, Caplan N, Moloney SB, Corkery A, Toms CJ, Thompson KG

British journal of sports medicine 45(15):A14 Research has previously shown that rowers commonly perform strength training three times per week. However, no research has assessed the impact that this weekly frequency of strength training may have on muscle function. Twenty-two highly trained male rowers were evenly assigned to two groups; intervention and control. All rowers performed baseline measures of a maximal isometric contraction of the leg extensors (MVC), five separate, static squat jumps (SSJ), counter-movement jumps (CMJ), and maximal rowing ergometer power strokes (PS) and a single 2000 m rowing ergometer test (2000 m). Intervention participants subsequently performed a protocol of three identical strength training (ST) sessions, in the space of 5 days with a day's break in-between the first to second and second to third sessions. The intervention group repeated the 2000 m test at 24 h following the final ST, in addition MVC, SSJ, CMJ and PS tests were performed. Muscle soreness (MS) and serum creatine kinase (CK) were assessed during both testing sessions for each group. Following the ST protocol, the intervention group experienced significant elevations in MS and CK (P < 0.001) coupled with decrements in MVC, SSJ, CMJ and PS, which ranged between 6-8% (P < 0.001). Values for these parameters were unchanged between both trials for the control group. Performance of the 2000 m test was not significantly affected by ST. No changes in 2000 m performance occurred from test to re-test in the control group. In summary, a series of strength training sessions resulted in symptoms of muscle damage and decrements in maximal power, but 2000 m ergometer performance was unaffected following strength training.

The effects of sprint interval training on aerobic fitness in untrained individuals: a systematic review. Kent W

British journal of sports medicine 45(15):A8, 2011 Dez Greater aerobic fitness is associated with improved cardiovascular health. Traditionally high volume (long duration and low intensity) endurance training (ET) has been used to increase aerobic fitness. Interval training where periods of hard exercise are interspersed with periods of recovery can also enhance endurance performance. Sprint interval training (SIT) is a low volume and high intensity form of interval training. Energy for SIT is produced via both the aerobic and anaerobic metabolic pathways and is potentially an efficient and effective means to improve aerobic fitness. The aim was to systematically review the effects of SIT on aerobic endurance performance in untrained individuals. PubMed, the Cochrane Library, ScienceDirect, and SPORTDiscus were searched up to August 2008. The reference lists of relevant papers were also searched. Included articles were limited to English language, controlled studies, investigating SIT in healthy untrained or recreationally active participants (VO(2max) < 55 ml/kg/min) with an outcome measure of endurance performance (as a measure of aerobic fitness). Studies fulfilling the selection criteria were assessed for methodological quality and relevant outcome data extracted. A consistent association was noted between SIT and improved endurance performance. SIT produced an improvement of ~ 4% (95%CI -0.2 to 8.7), ~8 to 10% (0.4 to 16), and ~15% (0.8 to 29) after 1, 2 and 6 weeks respectively. These improvements were of the same magnitude as the improvements noted for ET, but the training volume required was approximately 90% less. Short duration SIT is an effective and efficient form of improving aerobic fitness in untrained individuals. These results could have a significant impact upon physical activity recommendations for health and fitness if further studies can confirm the health benefits associated with longer duration ET also occur with brief SIT interventions.

Strength and neuromuscular adaptation following one, four, and eight sets of high intensity resistance exercise in trained males. Marshall PW, McEwen M, Robbins DW European journal of applied physiology 111(12):3007-16, 2011 Dez School of Biomedical and Health Science, University of Western Sydney, Sydney, Australia, Este endereço de e-mail está protegido de spam bots, pelo que necessita do Javascript activado para o visualizar .

The optimal volume of resistance exercise to prescribe for trained individuals is unclear. The purpose of this study was to randomly assign resistance trained individuals to 6-weeks of squat exercise, prescribed at 80% of a 1 repetition-maximum (1-RM), using either one, four, or eight sets of repetitions to failure performed twice per week. Participants then performed the same peaking program for 4-weeks. Squat 1-RM, quadriceps muscle activation, and contractile rate of force development (RFD) were measured before, during, and after the training program. 32 resistance-trained male participants completed the 10-week program. Squat 1-RM was significantly increased for all groups after 6 and 10-weeks of training (P < 0.05). The 8-set group was significantly stronger than the 1-set group after 3-weeks of training (7.9% difference, P < 0.05), and remained stronger after 6 and 10-weeks of training (P < 0.05). Peak muscle activation did not change during the study. Early (30, 50 ms) and peak RFD was significantly decreased for all groups after 6 and 10-weeks of training (P < 0.05). Peak isometric force output did not change for any group. The results of this study support resistance exercise prescription in excess of 4-sets (i.e. 8-sets) for faster and greater strength gains as compared to 1-set training. Common neuromuscular changes are attributed to high intensity squats (80% 1-RM) combined with a repetition to failure prescription. This prescription may not be useful for sports application owing to decreased early and peak RFD. Individual responsiveness to 1-set of training should be evaluated in the first 3-weeks of training.

Resistance Training vs. Static Stretching: Effects on Flexibility and Strength. Morton SK, Whitehead JR, Brinkert RH, Caine DJ

Journal of strength and conditioning research / National Strength & Conditioning Association 25(12):3391-8, 2011 Dez Department of Physical Education, Exercise Science, and Wellness (PXW), University of North Dakota, Grand Forks, North Dakota.

Morton, SK, Whitehead, JR, Brinkert, RH, and Caine, DJ. Resistance training vs. static stretching: Effects on flexibility and strength. J Strength Cond Res 25(12): 3391-3398, 2011-The purpose of this study was to determine how full-range resistance training (RT) affected flexibility and strength compared to static stretching (SS) of the same muscle-joint complexes in untrained adults. Volunteers (n = 25) were randomized to an RT or SS training group. A group of inactive volunteers (n = 12) served as a convenience control group (CON). After pretesting hamstring extension, hip flexion and extension, shoulder extension flexibility, and peak torque of quadriceps and hamstring muscles, subjects completed 5-week SS or RT treatments in which the aim was to stretch or to strength train the same muscle-joint complexes over similar movements and ranges. Posttests of flexibility and strength were then conducted. There was no difference in hamstring flexibility, hip flexion, and hip extension improvement between RT and SS, but both were superior to CON values. There were no differences between groups on shoulder extension flexibility. The RT group was superior to the CON in knee extension peak torque, but there were no differences between groups on knee flexion peak torque. The results of this preliminary study suggest that carefully constructed full-range RT regimens can improve flexibility as well as the typical SS regimens employed in conditioning programs. Because of the potential practical significance of these results to strength and conditioning programs, further studies using true experimental designs, larger sample sizes, and longer training durations should be conducted with the aim of confirming or disproving these results.

Maximal voluntary contraction force, SR function and glycogen resynthesis during the first 72 h after a high-level competitive soccer game. Krustrup P, Ortenblad N, Nielsen J, Nybo L, Gunnarsson TP, Iaia FM, Madsen K, Stephens F, Greenhaff P, Bangsbo J

European journal of applied physiology 111(12):2987-95, 2011 Dez Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark.

The aim of this study was to examine maximal voluntary knee-extensor contraction force (MVC force), sarcoplasmic reticulum (SR) function and muscle glycogen levels in the days after a high-level soccer game when players ingested an optimised diet. Seven high-level male soccer players had a vastus lateralis muscle biopsy and a blood sample collected in a control situation and at 0, 24, 48 and 72 h after a competitive soccer game. MVC force, SR function, muscle glycogen, muscle soreness and plasma myoglobin were measured. MVC force sustained over 1 s was 11 and 10% lower (P < 0.05) after 0 and 24 h, respectively, compared with control. The rate of SR Ca(2+) uptake at 800 nM [Ca(2+)](free) was lower (P < 0.05) after 0 h (2.5 µmol Ca(2+) g prot(-1) min(-1)) than for all other time points (24 h: 5.1 µmol Ca(2+) g prot(-1) min(-1)). However, SR Ca(2+) release rate was not affected. Plasma myoglobin was sixfold higher (P < 0.05) immediately after the game, but normalised 24 h after the game. Quadriceps muscle soreness (0-10 VAS-scale) was higher (P < 0.05) after 0 h (3.6), 24 h (1.8), 48 h (1.1) and 72 h (1.4) compared with control (0.1). Muscle glycogen was 57 and 27% lower (P < 0.001) 0 and 24 h after the game compared with control (193 and 328 vs. 449 mmol kg d w(-1)). In conclusion, maximal voluntary contraction force and SR Ca(2+) uptake were impaired and muscle soreness was elevated after a high-level soccer game, with faster recovery of SR function in comparison with MVC force, soreness and muscle glycogen.

Fit women are not able to use the whole aerobic capacity during aerobic dance. Edvardsen E, Ingjer F, Bø K

Journal of strength and conditioning research / National Strength & Conditioning Association 25(12):3479-85, 2011 Dez1Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway; and 2Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.

Edvardsen, E, Ingjer, F, and Bø, K. Fit women are not able to use the whole aerobic capacity during aerobic dance. J Strength Cond Res 25(12): 3479-3485, 2011-This study compared the aerobic capacity during maximal aerobic dance and treadmill running in fit women. Thirteen well-trained female aerobic dance instructors aged 30 ± 8.17 years (mean ± SD) exercised to exhaustion by running on a treadmill for measurement of maximal oxygen uptake (&OV0312;O2max) and peak heart rate (HRpeak). Additionally, all subjects performed aerobic dancing until exhaustion after a choreographed videotaped routine trying to reach the same HRpeak as during maximal running. The p value for statistical significance between running and aerobic dance was set to =0.05. The results (mean ± SD) showed a lower &OV0312;O2max in aerobic dance (52.2 ± 4.02 ml·kg·min) compared with treadmill running (55.9 ± 5.03 ml·kg·min) (p = 0.0003). Further, the mean ± SD HRpeak was 182 ± 9.15b·min in aerobic dance and 192 ± 9.62 b·min in treadmill running, giving no difference in oxygen pulse between the 2 exercise forms (p = 0.32). There was no difference in peak ventilation (aerobic dance: 108 ± 10.81 L·min vs. running: 113 ± 11.49 L·min). In conclusion, aerobic dance does not seem to be able to use the whole aerobic capacity as in running. For well endurance-trained women, this may result in a lower total workload at maximal intensities. Aerobic dance may therefore not be as suitable as running during maximal intensities in well-trained females.

Fatiguing upper body aerobic exercise impairs balance. Douris PC, Handrakis JP, Gendy J, Salama M, Kwon D, Brooks R, Salama N, Southard V

Journal of strength and conditioning research / National Strength & Conditioning Association 25(12):3299-305, 2011 DezDepartment of Physical Therapy, New York Institute of Technology, Old Westbury, New York.

Douris, PC, Handrakis, JP, Gendy, J, Salama, M, Kwon, D, Brooks, R, Salama, N, and Southard, V. Fatiguing upper body aerobic exercise impairs balance. J Strength Cond Res 25(12): 3299-3305, 2011-There are many studies that have examined the effects of selectively fatiguing lower extremity muscle groups with various protocols, and they have all shown to impair balance. There is limited research regarding the effect of fatiguing upper extremity exercise on balance. Muscle fiber-type recruitment patterns may be responsible for the difference between balance impairments because of fatiguing aerobic and anaerobic exercise. The purpose of our study was to investigate the effect that aerobic vs. anaerobic fatigue, upper vs. lower body fatigue will have on balance, and if so, which combination will affect balance to a greater degree. Fourteen healthy subjects, 7 men and 7 women (mean age 23.5 ± 1.7 years) took part in this study. Their mean body mass index was 23.6 ± 3.2. The study used a repeated-measures design. The effect on balance was documented after the 4 fatiguing conditions: aerobic lower body (ALB), aerobic upper body (AUB), anaerobic lower body, anaerobic upper body (WUB). The aerobic conditions used an incremental protocol performed to fatigue, and the anaerobic used the Wingate protocol. Balance was measured as a single-leg stance stability score using the Biodex Balance System. A stability score for each subject was recorded immediately after each of the 4 conditions. A repeated-measures analysis of variance with the pretest score as a covariate was used to analyze the effects of the 4 fatiguing conditions on balance. There were significant differences between the 4 conditions (p = 0.001). Post hoc analysis revealed that there were significant differences between the AUB, mean score 4.98 ± 1.83, and the WUB, mean score 4.09 ± 1.42 (p = 0.014) and between AUB and ALB mean scores 4.33 ± 1.40 (p = 0.029). Normative data for single-leg stability testing for this age group are 3.9 ± 1.9. Higher scores reflect greater balance deficits. The AUB condition produced the greatest balance deficit. Our data provide evidence of the important role of the upper body in maintaining unilateral standing balance and supports its inclusion as part of rehabilitation and training protocols designed to improve balance.

Factors of trainability and predictability associated with military physical fitness test success. Cuddy JS, Slivka DR, Hailes WS, Ruby BC

Journal of strength and conditioning research / National Strength & Conditioning Association 25(12):3486-94, 2011 DezDepartment of Health and Human Performance, Montana Center for Work Physiology and Exercise Metabolism, The University of Montana, Missoula, Montana.

Cuddy, JS, Slivka, DR, Hailes, WS, and Ruby, BC. Factors of trainability and predictability associated with military physical fitness test success. J Strength Cond Res 25(12): 3486-3494, 2011-The purpose of this study was to determine the trainability of college-aged men using varied training programs and to assess factors associated with successfully passing a Special Operations Forces (SOF) physical fitness test (PFT). One hundred thirty-five male subjects were stratified into 3 training groups (run focused, calisthenic focused, or combined run and calisthenic) and were trained 3 times·per week for 12 weeks. Body composition and accelerometer activity patterns were measured pretraining and posttraining. The PFT performance (pull-ups, sit-ups, push-ups, and 1.5-mile run time) was measured weekly throughout the study period. The subjects exhibited reduced body fat (18.4 ± 7.7 to 16.9 ± 7.3), increased fat-free mass (66.1 ± 8.2 to 67.4 ± 7.9), reduced fat mass (15.8 ± 9.2 to 14.6 ± 8.9) from pretraining to posttraining, respectively (p < 0.05). All groups improved in each component of PFT performance with training (p < 0.05). There was a significant 20 ± 35% increase in 6-day average daily activity for the run-focused training group from pretraining and posttraining. The key indicators of a candidate's potential to successfully reach SOF PFT standards (in 12 weeks) were determined to be as follows: enter the pipeline being able to run 2.4 km in =10:41 minutes, have a body fat percentage of =12.9%, and participate in a minimum of 30 min·d of vigorous physical activity. Training an individual's relative run or calisthenic deficiency did not prove to be a better training approach compared with a program that emphasizes training both running and calisthenic activities.

Effect of different warming-up protocols on time to exhaustion at maximal aerobic speed. Rodriguez de la Cruz C, Brennenraedts C, Bury T

Middle distance races are characterised by a start at high intensity without progression. Some studies focused on the warming-up (WU) effects on physiological parameters during race from 95% to 120% of the work rate at VO(2)max. The aim was to determine the efficiency of different WU protocols on time to exhaustion at maximal aerobic speed (M.A.S.). We recruited 11 middle distance runners (mean age 30±4 years, height 177± 7 cm, VO(2)max 59.7±6.4 mlO(2).min(-1).kg(-1), M.A.S. 17.7±1.16 km/h). Subjects performed a triangular aerobic test to determine M.A.S. and three randomised rectangular tests at M.A.S. after three different WU protocols at 7 days of interval. The three WU protocols consist in no warming-up; 20 min WU at 55% of VO(2)max (low WU); 15 min WU AT 55% and 5 min at ((speed at LT 1 + speed at O.B.L.A.) / 2) (intense WU). After the WU, subjects observed 5 min rest before the rectangular test. Blood lactate concentration was measured four times (before WU, after WU, before and after rectangular test); whereas heart rate, VO(2)and ventilation were monitored continually. The mean heart rate during the rectangular test was higher (p<0.05) from the 1st-7th min after low and intense WU than without WU. The VO(2)max kinetic was the same in the three tests. Average blood lactate concentration was similar at the end of the race in the three protocols (6.9±0.8 mmol.l(-1) without WU, 6.8±0.8 mmol.l(-1)low WU and 6.6±0.7 mmol.l(-1) intense WU). Time to exhaustion at M.A.S. was higher (p<0.05) after intense WU. Results suggest that the intense WU has a positive effect on time to exhaustion at M.A.S. and therefore on aerobic performance. This is probably the result of a faster cardiovascular adaptation.

Changes in a Top-Level Soccer Referee's Training, Match Activities, and Physiology Over an 8-Year Period: A Case Study.

Weston M, Gregson W, Castagna C, Breivik S, Impellizzeri FM, Lovell RJ.: International journal of sports physiology and performance, 201106 6(2):281-6. Athlete case studies have often focused on the training outcome and not the training process. Consequently, there is a dearth of information detailing longitudinal training protocols, yet it is the combined assessment of both outcome and process that enhances the interpretation of physical test data. We were provided with a unique opportunity to assess the training load, physical match performance, and physiological fitness of an elite soccer referee from the referee's final season before attaining full-time, professional status (2002) until the season when he refereed the 2010 UEFA Champions League and FIFA World Cup finals. An increased focus on on-field speed and gym-based strength training was observed toward the end of the study period and longitudinal match data showed a tendency for decreased total distances but an increased intensity of movements. Laboratory assessments demonstrated that VO2max remained stable (52.3 vs 50.8 mL·kg-1·min-1), whereas running speed at the lactate threshold (14.0 vs 12.0 km·h-1) and running economy (37.3 vs 43.4 mL·kg-1·min-1) both improved in 2010 compared with 2002

Effects of a 12-week resistance exercise program on physical self-perceptions in college students. Moore JB, Mitchell NG, Bibeau WS, Bartholomew JB.Res Q Exerc Sport, 82(2):291-301. There is an increase in literature suggesting exercise can promote positive changes in physical self-perceptions that can manifest as an increase in global self-esteem. In the present study, we assessed self-esteem using the hierarchical framework of the Exercise and Self-Esteem Model (EXSEM) along with cognitive facets at the subdomain level (e.g., competence, certainty, importance, and ideal self-discrepancy). This allowed for an analysis of cognitive facets as possible contributors to changes in physical self-perceptions. We addressed these aims with a sample of 120 college-age adults who completed a 12-week resistance exercise program. Results indicated significant improvements in self-perception constructs at all levels of the EXSEM. The hierarchical structure of the EXSEM was partially supported, as we observed successively smaller improvements at each level of the model (e.g., self-esteem showed lesser improvements than physical self-worth). In addition, a path model developed to explain the impact of strength changes on self-esteem proved a good fit for the data. Results are discussed in terms of contemporary models of self-perception, potential mediators of exercise on self-esteem, and the need to consider cognitive facets of self-perception.

Metabolic Alkalosis, Recovery and Sprint Performance - Int J Sports Med 2010; 31(11): 797-802

The acute effects of different whole-body vibration amplitudes and frequencies on flexibility and vertical jumping performance

Gerodimos V, Zafeiridis A, Karatrantou K, Vasilopoulou T, Chanou K, Pispirikou E.: Journal of science and medicine in sport / Sports Medicine Australia, 2010, 13(4):438-43. Department of Physical Education and Sport Sciences, University of Thessaly, Trikala, Greece.

Frequency and amplitude determine the training load of whole-body vibration (WBV) exercise and thereby possible neuromuscular adaptations. We investigated the effects of amplitude and frequency of a single bout of WBV on flexibility and squat jump performance (SJ) and the time-course of these effects. In the amplitude study, twenty-five females performed three vibration protocols (VPs) for 6 min at frequency of 25Hz and amplitudes of 4 mm, 6 mm, and 8 mm and one control protocol (CP). In the frequency study, eighteen females performed three VPs at 6mm amplitude and frequencies of 15 Hz, 20 Hz, and 30 Hz and one CP. Flexibility and SJ were measured before, immediately-post and 15 min recovery. All protocols were performed on a side-to-side alternating vibration plate. In the amplitude study, flexibility was improved (p<0.01) immediately-post in VP4, VP6, VP8 (31.8+/-8.2, 31.9+/-7.6, 31.5+/-7.9, respectively) and at 15 min recovery (31.6+/-8.1, 31.5+/-7.9, 31.0+/-8.2, respectively) vs. pre-vibration (30.2+/-8.6, 30.3+/-8.1, 30.2+/-8.3, respectively), but remained unchanged in CP (30.6+/-8.3 immediately-post, 30.7+/-8.2 at 15 min vs. 30.4+/-8.2 pre-vibration). In the frequency study, flexibility was improved (p<0.01) immediately-post in VP15, VP20, VP30 (31.5+/-5.2, 31.3+/-5, 31.7+/-5.3, respectively) and at 15 min recovery (31.3+/-5.4, 31.3+/-5.0, 31.3+/-5.3, respectively) vs. pre-vibration (30.6+/-5.4, 30.2+/-5.7, 30.3+/-5.9, respectively), but not in CP (30.7+/-5.1 immediately-post, 30.6+/-5 at 15 min vs. pre-vibration 30.5+/-5.7). There were no significant effects of amplitude or frequency on SJ. In conclusion, a single WBV bout using a side-to-side alternating vibration plate may increase flexibility which persists for at least 15 min, without altering jumping performance. These effects were observed irrespective of frequency and amplitude.

Heart rate recovery as a guide to monitor fatigue and predict changes in performance parameters

Lamberts RP, Swart J, Capostagno B, Noakes TD, Lambert MI.: Scandinavian Journal of Medicine & Science in Sports, 2010, 20(3):449-57. Department of Human Biology, The Sport Science Institute of South Africa, Faculty of Health Sciences, University of Cape Town, Newlands, South Africa.

Determining the optimal balance between training load and recovery contributes to peak performance in well-trained athletes. The measurement of heart rate recovery (HRR) to monitor this balance has become popular. However, it is not known whether the impairment in performance, which is associated with training-induced fatigue, is accompanied by a change in HRR. Therefore, the aim of this study was to retrospectively analyze the relationship between changes in HRR and cycling performance in a group of well-trained cyclists (n=14) who participated in a 4-week high-intensity training (HIT) program. Subjects were assigned to either a group that continuous had a increase in HRR (G(Incr)) or a group that showed a decrease in HRR (G(Decr)) during the HIT period. Both groups, G(Incr) and G(Decr), showed improvements in the relative peak power output (P=0.001 and 0.016, respectively) and endurance performance parameters (P=0.001 and <0.048, respectively). The average power during the 40-km time trial (40-km TT), however, improved more in G(Incr) (P=0.010), resulting in a tendency for a faster 40-km TT time (P=0.059). These findings suggest that HRR has the potential to monitor changes in endurance performance and contribute to a more accurate prescription of training load in well-trained and elite cyclists.

Effect of intermittent hypoxic training on 20 km time trial and 30 s anaerobic performance

Hamlin MJ, Marshall HC, Hellemans J, Ainslie PN, Anglem N.: Scandinavian Journal of Medicine & Science in Sports, 2010 20(4):651-61. Social Sciences Tourism & Recreation Group, Environment, Society and Design Division, Lincoln University, Canterbury, New Zealand.

This study aimed to verify whether the "live low, train high" approach is beneficial for endurance and/or anaerobic cycling performance. Sixteen well-trained athletes completed 90 min of endurance training (60-70% of heart rate reserve), followed by two 30-s all-out sprints (Wingate test), daily, for 10 consecutive days. Nine subjects [intermittent hypoxic training (IHT) group] trained with an F(I)O(2) set to produce arterial oxygen saturations of approximately 88-82%, while seven subjects (placebo group) trained while breathing a normal gas mixture (F(I)O(2)=0.21). Four performance tests were conducted at sea level including a familiarization and baseline trial, followed by repeat trials at 2 and 9 days post-intervention. Relative to the placebo group, the mean power during the 30-s Wingate test increased by 3.0% (95% confidence limits, CL +/- 3.5%) 2 days, and 1.7% (+/- 3.8%) 9 days post-IHT. Changes in other performance variables (30 s peak power, 20 km mean power and 20 km oxygen cost) were unclear. During the time trial, the IHT participants' blood lactate concentration, respiratory exchange ratio, and SpO(2), relative to the placebo group, was substantially increased at 2 days post-intervention. The addition of IHT to the normal training program of well-trained athletes produced worthwhile gains in 30 s sprint performance possibly through enhanced glycolysis.

Effects of music tempo upon submaximal cycling performance

Waterhouse J, Hudson P, Edwards B.: Scandinavian journal of medicine & science in sports, 2010, 20(4):662-9 Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, Liverpool, UK.

In an in vivo laboratory controlled study, 12 healthy male students cycled at self-chosen work-rates while listening to a program of six popular music tracks of different tempi. The program lasted about 25 min and was performed on three occasions--unknown to the participants, its tempo was normal, increased by 10% or decreased by 10%. Work done, distance covered and cadence were measured at the end of each track, as were heart rate and subjective measures of exertion, thermal comfort and how much the music was liked. Speeding up the music program increased distance covered/unit time, power and pedal cadence by 2.1%, 3.5% and 0.7%, respectively; slowing the program produced falls of 3.8%, 9.8% and 5.9%. Average heart rate changes were +0.1% (faster program) and -2.2% (slower program). Perceived exertion and how much the music was liked increased (faster program) by 2.4% and 1.3%, respectively, and decreased (slower program) by 3.6% and 35.4%. That is, healthy individuals performing submaximal exercise not only worked harder with faster music but also chose to do so and enjoyed the music more when it was played at a faster tempo. Implications of these findings for improving training regimens are discussed.

The use of an 8-week mixed-intensity interval endurance-training program improves the aerobic fitness of female soccer players

Clark JE.: Journal of strength and conditioning research / National Strength & Conditioning Association, 2010, 24(7):1773-81. Department of Biology, Division of Natural Sciences, Mt. San Antonio College, Walnut, California, USA.

The purpose of this study is to examine improvements in cardiorespiratory fitness (VO(2)) after the use of a mixed-intensity interval endurance-training (MI-ET) program in female soccer players, to validate the MI-ET program as an appropriate training regimen to improve cardiorespiratory fitness (VO(2)) in soccer players. 32 female soccer players (average 18.66 +/- 0.31 years) were recruited from a group of currently conditioning local U-19 and college soccer teams and randomly assigned to participate in an 8-week periodized training program that involved either the MI-ET program or the continuation of a current endurance-training (ET) program. Analysis of variance indicates no differences in VO(2) values within the group of athletes before participating in the exercise program. After the 8 weeks of training, the MI-ET group of athletes had significantly greater average VO(2) values (62.13 +/- 0.96 ml O2.kg.min vs. 57.27 +/- 1.59 ml O2.kg.min), p = 0.015, along with a greater group average of change in VO(2) (12.44 +/- 0.92 ml O2.kg.min vs. 7.72 +/- 0.99 ml O2.kg.min), p < 0.001. The MI-ET program is shown to be a valid means to improve aerobic fitness as indicated by the MI-ET group exhibiting significantly greater VO(2) measures after training.

The effects of whole-body compression garments on prolonged high-intensity intermittent exercise

Sear JA, Hoare TK, Scanlan AT, Abt GA, Dascombe BJ.: Journal of strength and conditioning research / National Strength & Conditioning Association, 2010, 24(7):1901-10. Sport Performance and Development, National Talent Identification and Development Program, Australian Sports Commission, Adelaide, South Australia, Australia.

The current study investigated the effects of wearing whole-body compression garments (WBCGs) on prolonged high-intensity intermittent exercise (PHIIE) performance. Eight male team-sport athletes ([X +/- SD] 20.6 +/- 1.2 years; 72.9 +/- 5.9 kg; 57.5 +/- 3.7 ml.kg.min) completed a prescribed 45-minute PHIIE protocol on a nonmotorized treadmill in randomly assigned WBCG and control (typical soccer apparel) conditions. Subjects were given verbal and visual cues for movement categories, and they followed set target speeds, except when instructed of a variable run or sprint where the aim was to run as fast as possible. Total distance, velocity-specific distance, and high-intensity self-paced running speeds were taken as performance indicators. Heart rate, VO(2), tissue oxygenation index (TOI), and tissue hemoglobin index (nTHi) were continuously monitored across the protocol. Blood-lactate concentration ([BLa(-)]) was measured every 15 minutes. Magnitude-based inferences suggested that wearing WBCGs provided moderate strength likely improvements in total distance covered (5.42 +/- 0.63 vs. 5.88 +/- 0.64 km; 88:10:2%; and eta = 0.6) and low-intensity activity distance (4.21 +/- 0.51 vs. 4.56 +/- 0.57 km; 83:14:3%; and eta = 0.6) compared with the control. A similar likely increase was also observed in the average TOI of the WBCG condition (53.5 +/- 8.3% vs. 55.8 +/- 7.2%; 87:11:2%; and eta = 0.6). The current data demonstrated that wearing WBCGs likely increased physical performance, possibly because of improvements in muscle oxygenation and associated metabolic benefits. Therefore, wearing WBCGs during PHIIE may benefit the physical performance of team-sport athletes by likely metabolic changes within the muscle between high-intensity efforts.

Effect of plyometric vs. dynamic weight training on the energy cost of running.

Berryman N, Maurel D, Bosquet L.: Journal of strength and conditioning research / National Strength & Conditioning Association, 2010, 24(7):1818-25. Department of Kinesiology, Exercise Physiology Laboratory, University of Montreal, Montreal, Canada.

The purpose of this study is to compare the effects of 2 strength training methods on the energy cost of running (Cr). Thirty-five moderately to well-trained male endurance runners were randomly assigned to either a control group (C) or 2 intervention groups. All groups performed the same endurance-training program during an 8-week period. Intervention groups added a weekly strength training session designed to improve neuromuscular qualities. Sessions were matched for volume and intensity using either plyometric training (PT) or purely concentric contractions with added weight (dynamic weight training [DWT]). We found an interaction between time and group (p < 0.05) and an effect of time (p < 0.01) for Cr. Plyometric training induced a larger decrease of Cr (218 +/- 16 to 203 +/- 13 ml.kg.km) than DWT (207 +/- 15 to 199 +/- 12 ml.kg.km), whereas it remained unchanged in C. Pre-post changes in Cr were correlated with initial Cr (r = -0.57, p < 0.05). Peak vertical jump height (VJHpeak) increased significantly (p < 0.01) for both experimental groups (DWT = 33.4 +/- 6.2 to 34.9 +/- 6.1 cm, PT = 33.3 +/- 4.0 to 35.3 +/- 3.6 cm) but not for C. All groups showed improvements (p < 0.05) in Perf3000 (C = 711 +/- 107 to 690 +/- 109 seconds, DWT = 755 +/- 87 to 724 +/- 77 seconds, PT = 748 +/- 81 to 712 +/- 76 seconds). Plyometric training were more effective than DWT in improving Cr in moderately to well-trained male endurance runners showing that athletes and coaches should include explosive strength training in their practices with a particular attention on plyometric exercises. Future research is needed to establish the origin of this adaptation.

Determinants of the variability of heart rate measures during a competitive period in young soccer players.

Buchheit M, Mendez-Villanueva A, Quod MJ, Poulos N, Bourdon P.: European journal of applied physiology, 2010-07 109(5):869-78. Performance Enhancement and Talent Identification Section, ASPIRE, Academy for Sports Excellence, P.O. Box 22287, Doha, Qatar.

Measurements of exercise heart rate (HR(ex)), HR recovery (HRR) and HR variability (HRV) are used as indices of training status. However, the day-to-day variability of these indices throughout a competitive soccer period is unknown. On 14 occasions during a 3-week competition camp, 18 under 15 (U15) and 15 under 17 (U17) years soccer players performed a 5-min submaximal run, followed by a seated 5-min recovery period. HR(ex) was determined during the last 30 s of exercise, while HRR and HRV were measured during the first and last 3 min of the post-exercise recovery period, respectively. U15 players displayed greater HR(ex) (P = 0.02) and HRR (P = 0.004) compared with the U17 players, but there was no difference in HRV (P = 0.74). The mean coefficient of variation (CV) for HR(ex) was lower than that for HRV [3.4 (90% CL, 3.1, 3.7) vs. 10.7 (9.6, 11.9)%, P < 0.001]; both were lower than that for HRR [13.3 (12.2, 14.3)%, P < 0.01]. In contrast to HR(ex) and HRR, the CV for HRV was correlated to maximal aerobic speed (r = -0.52, P = 0.002). There was no correlation between total activity time (training sessions + matches) and CV of any of the quantified variables. The variability of each of these measures and player fitness levels should be considered when interpreting changes in training status.

Exercise intensity of head-out water-based activities (water fitness).

Raffaelli C, Lanza M, Zanolla L, Zamparo P.: European journal of applied physiology, 2010-07 109(5):829-38. Department of Neurological and Visual Sciences, Faculty of Exercise and Sport Sciences, University of Verona, via F. Casorati 43, 37131, Verona, Italy.

The aims of this study were: (i) to measure the exercise intensity (EI) of the most common water-based exercises (WE) at different movement frequencies (f1 = 1.8-2.0 Hz; f2 = 2.0-2.2 Hz; f3 = 2.2-2.4 Hz) and at a standardize movement's amplitude; (ii) to measure EI during a combination (MIX) of these WE. Five WE were selected: "running raising the knees high" (S); "jumping moving the legs sideways" (SJ); "jumping moving the legs backward and forward" (FJ); "alternate forward kicks" (FK); "alternate sideways kicks" (SK). Twelve physically active women were asked to perform these WE at the three frequencies, as well as a combination (MIX) of the WE. EI increased significantly (p < 0.01) with increasing frequency; as an average, for all WE: VO2 ranged from 18 to 25 ml kg(-1) min(-1), HR from 102 to 138 bpm, RPE from 9.8 to 14.4 (at f1 and f3, respectively). In terms of % VO2max, EI ranged from 37 to 54% for S, was similar for SJ and FJ (31-43%) and for FK and SK (47-63%) at f1 and f3, respectively. Thus, a given EI can be attained either by changing the type of exercise and/or the frequency of the movement. The combination of exercises did not change (in terms of VO2, HR and RPE) the intensity of each exercise performed separately. These data can be utilized to control, in terms of exercise type and frequency, the intensity of a proposed water-based activity.

Strength training in endurance runners.

Taipale RS, Mikkola J, Nummela A, Vesterinen V, Capostagno B, Walker S, Gitonga D, Kraemer WJ, Häkkinen K.: International journal of sports medicine, 2010-07 31(7):468-76. Department of Biology of Physical Activity, University of Jyväskylä, Finland.

This study examined effects of periodized maximal versus explosive strength training and reduced strength training, combined with endurance training, on neuromuscular and endurance performance in recreational endurance runners. Subjects first completed 6 weeks of preparatory strength training. Then, groups of maximal strength (MAX, n=11), explosive strength (EXP, n=10) and circuit training (C, n=7) completed an 8-week strength training intervention, followed by 14 weeks of reduced strength training. Maximal strength (1RM) and muscle activation (EMG) of leg extensors, countermovement jump (CMJ), maximal oxygen uptake (VO(2MAX)), velocity at VO(2MAX) (vVO(2MAX)) running economy (RE) and basal serum hormones were measured. 1RM and CMJ improved (p<0.05) in all groups accompanied by increased EMG in MAX and EXP (p<0.05) during strength training. Minor changes occurred in VO(2MAX), but vVO(2MAX) improved in all groups (p<0.05) and RE in EXP (p<0.05). During reduced strength training 1RM and EMG decreased in MAX (p<0.05) while vVO(2MAX) in MAX and EXP (p<0.05) and RE in MAX (p<0.01) improved. Serum testosterone and cortisol remained unaltered. Maximal or explosive strength training performed concurrently with endurance training was more effective in improving strength and neuromuscular performance and in enhancing vVO (2MAX) and RE in recreational endurance runners than concurrent circuit and endurance training.

Throwing performance is associated with muscular power.

Bourdin M, Rambaud O, Dorel S, Lacour JR, Moyen B, Rahmani A.: International journal of sports medicine, 2010-07 31(7):505-10. Université de Lyon, Université Lyon 1, INRETS, LBMC, UMR_T 9406, Oullins, France.

The aim of the present study was to test the hypothesis that performance in throwing events is associated with muscular characteristics of both upper and lower limbs. Thirty-eight male throwers volunteered to participate. Bench press and half squat tests were conducted on a guided barbell. The barbell displacement signal was recorded using a kinematic system. Maximal power, corresponding optimal velocity and force (P(max)S, V(opt)S, F(opt)S and P(max)BP, V(opt)BP, F(opt)BP for half squat and bench press, respectively) were extrapolated from the power-velocity relationship. Lower limb stiffness (K) was determined during maximal hopping. The results demonstrated that P(max)S and P(max)BP were correlated with each thrower's season's best performance (SBP, R=0.54, P<0.01 and R=0.71, P<0.001, respectively). P(max)S expressed relative to body mass was not correlated with SBP. K was significantly correlated with SBP (R=0.66, P<0.001). The relationship between P (max)BP expressed relative to body mass and SBP remained significant ( R=0.54, P<0.001). The results of the study suggest that high strength and stiffness values for lower limbs and strength and velocity characteristics for upper limbs may be associated with athletic throwing performance.

Effect of isokinetic cycling versus weight training on maximal power output and endurance performance in cycling.

Koninckx E, Van Leemputte M, Hespel P.: European Journal of Applied Physiology, 2010, 109(4):699-708. Department of Biomedical Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, Research Centre For Exercise and Health, K.U. Leuven, Tervuursevest 101, Box 1501, 3001 Leuven, Belgium.

The aim of this study was to compare the effects of a weight training program for the leg extensors with isokinetic cycling training (80 rpm) on maximal power output and endurance performance. Both strength training interventions were incorporated twice a week in a similar endurance training program of 12 weeks. Eighteen trained male cyclists (VO(2peak) 60 +/- 1 ml kg(-1) min(-1)) were grouped into the weight training (WT n = 9) or the isokinetic training group (IT n = 9) matched for training background and sprint power (P (max)), assessed from five maximal sprints (5 s) on an isokinetic bicycle ergometer at cadences between 40 and 120 rpm. Crank torque was measured (1 kHz) to determine the torque distribution during pedaling. Endurance performance was evaluated by measuring power, heart rate and lactate during a graded exercise test to exhaustion and a 30-min performance test. All tests were performed on subjects' individual race bicycle. Knee extension torque was evaluated isometrically at 115 degrees knee angle and dynamically at 200 degrees s(-1) using an isokinetic dynamometer. P (max) at 40 rpm increased in both the groups (~15%; P < 0.05). At 120 rpm, no improvement of P (max) was found in the IT training group, which was possibly related to an observed change in crank torque at high cadences (P < 0.05). Both groups improved their power output in the 30-min performance test (P < 0.05). Isometric knee extension torque increased only in WT (P < 0.05). In conclusion, at low cadences, P (max) improved in both training groups. However, in the IT training group, a disturbed pedaling technique compromises an improvement of P (max) at high cadences.

Race performance in male mountain ultra-marathoners: anthropometry or training?

Knechtle B, Knechtle P, Rosemann T.: Perceptual and Motor Skills, 2010, 110(3 Pt 1):721-35 . Facharzt FMH für Allgemeinmedizin, Gesundheitszentrum St. Gallen, St. Gallen, Switzerland.

The association of anthropometric variables, training volume, and prerace experience with race time was investigated in 25 male mountain ultra-marathoners (M age = 44.5 yr., SD = 7.0; M body mass = 73.0 kg, SD = 7.8; M body height = 1.78 m, SD = 0.07; M Body Mass Index = 22.9 kg/m2, SD = 1.8) in a 7-day mountain ultra-marathon over 350 km with a total 11,000 m of altitude gained and lost. The relationship of anthropometry (body mass, body height, Body Mass Index, percent body fat, circumferences of limbs, and thicknesses of skin-folds), training, and prerace experience (years as active runner, average training volume in hours and kilometres per week, average running speed in training, and personal best time in marathon running) with total race time was investigated using bivariate correlation analysis. None of the variables of anthropometry were related to total race time. Average speed in running during training and personal best time in marathon running were associated with total race time. Speed in running during training was correlated with personal best time in marathon running. The finding that average speed in running during training and personal best marathon time were related to race performance suggests that training and especially intensity might be of increased importance in these ultra-runners compared to anthropometry.

Personal best marathon performance is associated with performance in a 24-h run and not anthropometry or training volume.

Knechtle B, Wirth A, Knechtle P, Zimmermann K, Kohler G.: British Journal of Sports Medicine, 2009, 43(11):836-9. Facharzt FMH für Allgemeinmedizin, Gesundheitszentrum, Vadianstrasse 26, CH-9001 St Gallen, Switzerland.

Objective: In this study, the influence of anthropometric and training parameters on race performance in ultra-endurance runners in a 24-h run was investigated. Design: Descriptive field study. Setting: 24-h run in Basel 2007. Participants: 15 male Caucasian ultra-runners (mean (SD) 46.7 (5.8 years), 71.1 (6.8 kg), 1.76 (0.07 m), body mass index 23.1 (1.84 kg/m(2))). Interventions: None. Main Outcome Measures: Age, body mass, body height, length of lower limbs, skin-fold thicknesses, circumference of extremities, skeletal muscle mass, body mass, percentage of body fat, and training volume in 15 successful finishers were determined to correlate anthropometric and training parameters with race performance. Results: No significant association (p>0.05) was found between the reached distance and the anthropometric properties. There was also no significant association between the reached distance with the weekly training hours, running years, the number of finished marathons and the number of finished 24-h runs. The reached distance was significantly (p<0.05) positively correlated with the personal best marathon performance (r(2) = 0.40) and the personal best 24-h run distance (r(2) = 0.58). Furthermore, the personal best marathon performance was significantly and positively correlated (p<0.01) with the best personal 24-h run distance (r(2) = 0.76). Conclusions: Anthropometry and training volume does not seem to have a major effect on race performance in a 24-h run. Instead, a fast personal best marathon time seems to be the only positive association with race performance in a 24-h run.

Concurrent endurance and strength training not to failure optimizes performance gains.

Izquierdo-Gabarren M, González De Txabarri Expósito R, García-pallarés J, Sánchez-medina L, De Villarreal ES, Izquierdo M.: Medicine and Science in Sports and Exercise, 2010, 42(6):1191-9. Research Center of Rowing Club Orio, Orio,

Purpose: The purpose of this study was to examine the efficacy of 8 wk of resistance training to failure versus not to failure training regimens at both moderate and low volumes for increasing upper-body strength and power as well as cardiovascular parameters into a combined resistance and endurance periodized training scheme. Methods: Forty-three trained male rowers were matched and then randomly assigned to four groups that performed the same endurance training but differed on their resistance training regimen: four exercises leading to repetition failure (4RF; n = 14), four exercises not leading to failure (4NRF; n = 15), two exercises not to failure (2NRF; n = 6), and control group (C; n = 8). One-repetition maximum strength and maximal muscle power output during prone bench pull (BP), average power during a 20-min all-out row test (W 20 min), average row power output eliciting a blood lactate concentration of 4 mmol x L(-1) (W 4 mmol x L(-1)), and power output in 10 maximal strokes (W 10 strokes) were assessed before and after 8 wk of periodized training. Results: 4NRF group experienced larger gains in one- repetition maximum strength and muscle power output (4.6% and 6.4%, respectively) in BP compared with both 4RF (2.1% and j1.2%) and 2NRF (0.6% and -0.6%). 4NRF and 2NRF groups experienced larger gains in W 10 strokes (3.6% and 5%) and in W 20 min (7.6% and 9%) compared with those found after 4RF (-0.1% and 4.6%), whereas no significant differences between groups were observed in the magnitude of changes in W 4 mmol x L(-1) (4NRF = 6.2%, 4RF = 5.3%, 2NRF = 6.8%, and C = 4.5%). Conclusions: An 8-wk linear periodized concurrent strength and endurance training program using a moderate number of repetitions not to failure (4NRF group) provides a favorable environment for achieving greater enhancements in strength, muscle power, and rowing performance when compared with higher training volumes of repetitions to failure in experienced highly trained rowers.

Physiological and psychological fatigue in extreme conditions: overtraining and elite athletes.

Purvis D, Gonsalves S, Deuster PA.: PM & R : the journal of injury, function, and rehabilitation, 2010, 2(5):442-50. Departments of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.

This article will review relevant mechanisms and markers associated with overtraining syndrome (OTS), and discuss signs and symptoms, differential diagnosis, and current assessment tools for fatigue within the context of overtraining. The findings are drawn from original research and review articles referenced by PubMed and ScienceDirect databases. Sources were selected for their contributions to the current knowledge of biological, psychological, and molecular mechanisms. Data were reviewed for relevance to OTS and then evaluated against criteria that included significant OTS outcomes and findings. Information was systematically analyzed to identify patterns, dependencies, connections, and causal factors. Comparative analysis was confounded by inconsistent metrics, terminology, and variable methodology; potential biomarkers, treatment and prevention approaches, and future research directions are identified. Diagnosing OTS is difficult because underlying cause(s) are unknown; one must exclude other factors that degrade performance and mood status. Many studies are confounded by inadequate experimental designs, poor measures of performance, and different methods for characterizing OTS. OTS is complex because the demands of excessive training in combination with other biologic, psychological, and social stressors are difficult to quantify. However, changes in mood are always noted. Interrelations among dietary patterns; social, psychological and physiological profiles; and the neuroendocrine, immune, and central nervous systems are complex and not adequately elucidated.

Ergogenic effect of acupuncture in sport and exercise: a brief review.

Ahmedov S.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(5):1421-7. School of Physical Education & Sport, Near East University, Nicosia, Turkey.

Acupuncture is one of the most popular alternative methods applied in Western medical practice. In addition to its curative properties in various chronic conditions, demonstrated by the number of clinical trials, acupuncture has been recently applied as an enhancer of Sports performance. Reviewed studies of published literature on the use of acupuncture in resistance and endurance Sports activities demonstrated the association of traditional acupuncture protocol with increase of muscular strength and power. In cases regarding endurance activities, acupuncture treatment improved hemodynamic parameters of participants but not their aerobic performance. Further methodologically strong studies with inclusion of both biomedical and traditional Chinese theories are needed to assess the usefulness of acupuncture in enhancement of Sports performance.

Genetics and Sports.

Lippi G, Longo UG, Maffulli N.: British Medical Bulletin, 2010, 93:27-47. di Chimica Clinica, Università di Verona, Italy.

Introduction: The limit of each individual to perform a given type of exercise depends on the nature of the task, and is influenced by a variety of factors, including psychology, environment and genetic make up. Genetics provide useful insights, as sport performances can be ultimately defined as a polygenic trait. SOURCES OF DATA: We searched PubMed using the terms 'Sports' and 'genetics' over the period 1990 to present. AREAS OF AGREEMENT: The physical performance phenotypes for which a genetic basis can be suspected include endurance capacity, muscle performance, physiological attitude to train and ability of tendons and ligaments to withstand injury. Genetic testing in sport would permit to identify individuals with optimal physiology and morphology, and also those with a greater capacity to respond/adapt to training and a lesser chance of suffering from injuries. AREAS OF CONTROVERSY: Ethical and practical caveats should be clearly emphasized. The translation of an advantageous genotype into a champion's phenotype is still influenced by environmental, psychological and sociological factors. EMERGING AREAS FOR DEVELOPING RESEARCH: The current scientific evidence on the relationship between genetics and Sports look promising. There is a need for additional studies to determine whether genome-wide genotyping arrays would be really useful and cost-effective. Since exercise training regulates the expression of genes encoding various enzymes in muscle and other tissues, genetic research in Sports will help clarify several aspects of human biology and physiology, such as RNA and protein level regulation under specific circumstances.

Anthropometric characteristics and motor skills in talent selection and development in indoor soccer.

Ré AH, Corrêa UC, Böhme MT.: Perceptual and Motor Skills, 2010, 110(3 Pt 1):916-30. Physical Activity Sciences School of Arts, Sciences, and Humanities, University of São Paulo, Brasil.

Kick performance, anthropometric characteristics, slalom, and linear running were assessed in 49 (24 elite, 25 nonelite) postpubertal indoor soccer players in order to (a) verify whether anthropometric characteristics and physical and technical capacities can distinguish players of different competitive levels, (b) compare the kicking kinematics of these groups, with and without a defined target, and (c) compare Results on the assessments and coaches' subjective rankings of the players. Thigh circumference and specific technical capacities differentiated the players by level of play; cluster analysis correctly classified 77.5% of the players. The correlation between players' standardized measures and the coaches' rankings was 0.29. Anthropometric characteristics and physical capacities do not necessarily differentiate players at post-pubertal stages and should not be overvalued during early development. Considering the coaches' rankings, performance measures outside the specific game conditions may not be useful in identification of talented players.

Moderate association of anthropometry, but not training volume, with race performance in male ultraendurance cyclists.

Knechtle B, Wirth A, Knechtle P, Rosemann T.: Research Quarterly for Exercise and Sport

200909 80(3):563-8. St. Gallen Health Center, St. Gallen, Switzerland.

In 28 male Caucasian nonprofessional ultracyclists, we investigated whether anthropometry or training volume had an influence on race speed in the 600 km at the Swiss Cycling Marathon 2007. Anthropometric parameters (age, body mass, body height, skinfold thicknesses) were determined before the race to calculate body mass index and percent body fat. In addition, participants, using a training diary, recorded their training volume in hours and kilometers in the 3 months before the race. The influence of anthropometry and training volume on speed in the race as the dependent variable was investigated in a multiple linear regression model. Anthropometry showed a moderate association with speed in the race (r2 = .178, p .05). We concluded that anthropometry had a greater influence on race performance than training volume in recreational ultraendurance cyclists.

Effect of cold water immersion on 100-m sprint performance in well-trained swimmers.

Parouty J, Al Haddad H, Quod M, Leprêtre PM, Ahmaidi S, Buchheit M.: European Journal of Applied Physiology, 2010, 109(3):483-90. Research Laboratory, EA 3300 Laboratory of Exercise Physiology and Rehabilitation, Faculty of Sport Sciences, University of Picardie Jules Verne, Amiens, France.

The aim of the present study was to examine the effect of cold water immersion (CWI) on sprint swimming performance in simulated competition conditions. Ten well-trained swimmers (5 males, 5 females; 19.0 +/- 3.9 years) performed two 100-m swimming sprints (S1 and S2) interspersed with a 30-min passive recovery period, during which athletes were randomly assigned to 5 min of CWI (14 degrees C) or an out-of-water control condition (CON 28 degrees C). During tests, sprint times, heart rate (HR), pre- and post-race parasympathetic activity via HR variability (natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals; Ln rMSSD) and blood lactate accumulation ([La](ac)) and clearance ([La](cle)) were recorded. Rates of perceived recovery (RPR) and exertion (RPE) were evaluated before and after each sprint. CWI was associated with a 'likely' decrease in swimming performance [1.8% (90% CI 0.2, 3.5)], as well as 'likely' lower peak HR [-1.9% (-3.6, -0.2)]. CWI was also associated with a 'likely' smaller decrease in Ln rMSSD after the first sprint [-16.7% (-30.9, -4.1)]. RPR was 'likely' better [+27.2% (-3.7, 68.0)] following CWI. 'unclear' effects were observed for [La](ac) [+24.7% (-13.4, 79.5)], [La](cle) [-7.6% (-24.2, 12.7)] or RPE [+2.0% (-12.3, 18.5)]. Following CWI, changes in sprint times were 'largely' correlated with changes in peak HR (r = 0.80). Despite a subjective perception of improved recovery following CWI, this recovery intervention resulted in slower swimming times in well-trained athletes swimming in simulated competition conditions.

Eight-week traditional mat Pilates training-program effects on adult fitness characteristics.

Rogers K, Gibson AL.: Research Quarterly for Exercise and Sport, 2009, 80(3):569-74. Wellness Center, University of Miami, USA.

We investigated responses of adult, novice practitioners (n = 9) to an 8-week traditional mat Pilates program (P) that met 1 hr/day three times/week. Classes consisted primarily of beginner and intermediate level exercises. Compared to an active control group (C; n = 13) that showed no improvements, those in P significantly (p < .05) improved relative body fat (-1.2% BF), sit-and-reach (+7.5 cm), shoulder reach (+6.9 cm), curl-up (+14 reps), and low back extension (+7 reps) scores, as well as circumferences at the waist (-2.7 cm), chest (-1.7 cm), and arm (-0.5 cm). Baseline differences were noted only for curl-ups and low back extensions, with P being lower than C Body composition, muscular endurance, and flexibility significantly improved after 8 weeks of traditional mat Pilates.

World records: how much athlete? How much technology?

De Koning JJ.: International Journal of Sports Physiology and Performance, 2010, 5(2):262-7. Research Institute MOVE, Faculty of Human Movement Sciences, VU-University Amsterdam, Amsterdam, the Netherlands.

The quality of performance during international competitions such as the Olympic Games and various world championships is often judged by the number of world records attained. The simple fact that world records continue to improve is evidence that Sports performance is progressing. Does this also mean that athletes are improving? Is the continual progression of world-record performances evidence that contemporary athletes are superior to the athletes who performed in the past? Technological developments may obscure insight into the athletic enhancement made by athletes over the years. This commentary tries to separate technological and athletic enhancement in the progression of world records by the use of a power balance model.

Relationship between muscle strength, power and stiffness and running economy in trained male runners.

Dumke CL, Pfaffenroth CM, McBride JM, McCauley GO.: International Journal of Sports Physiology and Performance, 2010, 5(2):249-61 . Department of Health and Human Performance, University of Montana, Missoula, Montana, USA.

Purpose: In this study, a comparison was made between muscle strength, power and muscle and tendon (km and kt respectively) stiffness of the triceps surae muscle group and running economy (RE) in trained male runners. Methods: Twelve well-trained male runners (age = 21 +/- 2.7 y, height = 178.1 +/- 7.1 cm, body mass = 66.7 +/- 3.2 kg, VO2max = 68.3 +/- 4.3 mL x kg(-1) x min(-1), 5000-m time = 15:04 min:s) underwent passive stiffness testing using a free oscillation method. Muscle strength was determined via a maximal isometric squat test and power determined via a maximal countermovement jump (CMJ). On a separate day, subjects performed an incremental treadmill test and their RE, lactate threshold, and VO2max were determined. Fingertip blood lactate was determined at the end of each 3-min stage. Lactate threshold was defined as a nonlinear increase in lactate accumulation. Results: A statistically significant correlation was found between km and VO2 at stage 6 (r = -0.69, P = .01). In addition, statistically significant correlations were observed between CMJ peak force production and VO2 at stage 2 (r = .66, P = .02), stage 3 (r = .70, P = .01), and stage 4 (r = .58, P = .04). No other statistically significant correlations were observed. Conclusion: These data suggest that greater muscle stiffness and less power are associated with greater RE. Future study in this area should focus on determining the mechanisms behind this relationship and how to best apply them to a running population through training techniques.

Improving acceleration and repeated sprint ability in well-trained adolescent handball players: speed versus sprint interval training.

Buchheit M, Mendez-Villanueva A, Quod M, Quesnel T, Ahmaidi S.: International Journal of Sports Physiology and Performance, 2010, 5(2):152-64. Research Laboratory, EA 3300-Exercise Physiology and Rehabilitation, Faculty of Sport Sciences, University of Picardie, Jules Verne, Amiens, France.

Purpose: The aim of the current study was to compare the effects of speed/agility (S/A) training with sprint interval training (SIT) on acceleration and repeated sprint ability (RSA) in well-trained male handball players. Methods: In addition to their normal training program, players performed either S/A (n = 7) or SIT (n = 7) training for 4 wk. Speed/agility sessions consisted of 3 to 4 series of 4 to 6 exercises (eg, agility drills, standing start and very short sprints, all of <5 s duration); each repetition and series was interspersed with 30 s and 3 min of passive recovery, respectively. Sprint interval training consisted of 3 to 5 repetitions of 30-s all-out shuttle sprints over 40 m, interspersed with 2 min of passive recovery. Pre- and posttests included a countermovement jump (CMJ), 10-m sprint (10m), RSA test and a graded intermittent aerobic test (30-15 Intermittent Fitness Test, V(IFT)). Results: S/A training produced a very likely greater improvement in 10-m sprint (+4.6%, 90% CL 1.2 to 7.8), best (+2.7%, 90% CL 0.1 to 5.2) and mean (+2.2%, 90% CL -0.2 to 4.5) RSA times than SIT (all effect sizes [ES] greater than 0.79). In contrast, SIT resulted in an almost certain greater improvement in V(IFT) compared with S/A (+5.2%, 90% CL 3.5 to 6.9, with ES = -0.83). Conclusion: In well-trained handball players, 4 wk of SIT is likely to have a moderate impact on intermittent endurance capacity only, whereas S/A training is likely to improve acceleration and repeated sprint performance.

Long-term success and risk for marathon runners

Schueller-Weidekamm C.: Der Radiologe, 2010, 50(5):444-52. Abteilung für Neuroradiologie und muskuloskelettale Radiologie, Klinik für Radiodiagnostik, Medizinische Universität Wien, AKH, Währinger Gürtel 18-20, A-1090, Wien, Osterreich.

The popularity of marathon running has increased during recent years, which is reflected by the dramatic increase in the number of competitions and participants. Running a marathon itself does not usually cause any severe lesions of the joints but the problems mostly occur during training prior to the marathon. Before the event runners often question whether they can successfully take part in the competition and cope with the pain that might occur during running. In addition to the rare acute trauma, which is in general caused by falls or slipping, chronic injuries are of particular relevance for long distance running.This article describes the typical patterns of injuries to long distance runners, the positive effects of running a marathon and the risk factors for injuries.

The effects of jump-rope training on shoulder isokinetic strength in adolescent volleyball players.

Duzgun I, Baltaci G, Colakoglu F, Tunay VB, Ozer D.: Journal of Sport Rehabilitation , 2010, 19(2):184-99. Dept of Physical Therapy and Rehabilitation, Gazi University, Ankara, Turkey.

Objective: To investigate the effect of a 12-wk weighted-jump-rope training program on shoulder strength. Design: Pretest to posttest experimental design. Setting: University Sports physiotherapy laboratory. Participants: 24 healthy volleyball players age 13-16 y. Intervention: Group 1 took weighted-rope training (n = 9), group 2 took unweighted-rope training (n = 8), and group 3 did not train with any specific program (n = 7). Main Outcome Measures: Players' strength determined with an isokinetic dynamometer (Isomed 2000) at 180 and 60 degrees on external and internal rotators, supraspinatus peak torque, and total work of the dominant shoulder. Kruskal-Wallis and Mann-Whitney U tests were used to determine the difference among the groups. Results: At pretraining evaluation, there were no significant differences in the test scores of the isokinetic test of full can and empty can between the groups at 60 and 180 degrees. There was no statistically significant difference for 60 and 180 degrees between pretraining and posttraining assessment (P > .05) except that total eccentric work increased in groups 1 and 3 but decreased in group 2 at 180 degrees during the full can (P .05). Internal-rotation values at 60 and 180 degrees decreased for both peak torque and total work for all groups. External-rotation peak torque and total work at 60 degrees increased for group 1. External-rotation peak torque and total work at 180 degrees increased for all groups. Conclusions: The Results indicate that a jump-rope training program is a good conditioning method for overhead athletes because of its potential benefits to shoulder strength.

Acute effects of different warm-up methods on sprint, slalom dribbling, and penalty kick performance in soccer players.

Gelen E.: Journal of Strength and Conditioning research / National Strength & Conditioning Association

201004 24(4):950-6. Sakarya University, School of Physical Education and Sport, Sakarya, Turkey.

Although pre-event static stretching is an accepted practice in most athletics program, pre-event dynamic exercise is becoming popular. The purpose of this study was to compare the acute effects of different warm-up methods on soccer performance. Twenty-six professional soccer players (23.3 +/- 3.2 years, 178.2 +/- 6.1 cm, and 73.0 +/- 6.5 kg) performed 4 different warm-up routines in random order on nonconsecutive days. The warm-up methods consisted of only 5 minutes of jogging (Method A), 5 minutes of jogging and static stretching (Method B), 5 minutes of jogging and dynamic exercise (Method C), and 5 minutes of jogging and a combination of static stretching and dynamic exercise (Method D). After each warm-up session, subjects were tested on the sprint, slalom dribbling, and penalty kick performance. Methods A-D were compared by repeated-measures analyses of variance and post hoc comparisons. In this study, existence of a significant drop in sprint, slalom dribbling, and penalty kick performances of Method C has been determined in comparison with that of Method A (p < 0.05). Again for sprint, slalom dribbling, and penalty kick performances of Method A in comparison with those of Method A, the existence of a significant increase has been determined (p 0.05). The results of this study suggest that it may be desirable for soccer players to perform dynamic exercises before the performance of activities that require a high power output.

Whole-body vibration training effects on the physical performance of basketball players.

Colson SS, Pensini M, Espinosa J, Garrandes F, Legros P.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010-04 24(4):999-1006. Laboratory of Human Motricity, Education and Health, University of Nice-Sophia Antipolis, Nice Cedex 03, France.

The aim of this study was to investigate the influence of 4 weeks of whole-body vibration training added to the conventional training of basketball players. Eighteen competitive basketball players (13 male symbol, 5 female symbol, 18-24 years old) were randomly assigned to a whole-body vibration group (WBVG, n = 10; 7 male symbol and 3 female symbol) or a control group (CG, n = 8; 6 male symbol and 2 female symbol). During the 4-week period, all subjects maintained their conventional basketball training program. The members of WBVG were additionally trained 3 times a week for 20 minutes on a vibration platform (10 unloaded static lower limb exercises, 40-Hz, 4-mm, Silverplate). Testing was performed before and after the 4-week period and comprised strength assessment, vertical jump performance, and a 10-m sprint test. The maximal voluntary isometric strength of the knee extensors significantly increased (p < 0.001) after vibration training, as did squat jump (SJ) height (p < 0.05), whereas performance of the countermovement jump, drop jump, 30-second rebound jump, and 10-m sprint remained unchanged. The results of the present study indicated that a 4-week whole-body vibration training program added to the conventional training of basketball players during the preseason is an effective short-term stimulus to enhance knee extensor strength and slightly SJ performance.

Talent identification and promotion programmes of Olympic athletes.

Vaeyens R, Güllich A, Warr CR, Philippaerts R.: Journal of Sports Sciences, 2009-11 27(13):1367-80. Department of Movement and Sports Sciences, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.

The start of a new Olympic cycle offers a fresh chance for individuals and nations to excel at the highest level in sport. Most countries attempt to develop systematic structures to identify gifted athletes and to promote their development in a certain sport. However, forecasting years in advance the next generation of sporting experts and stimulating their development remains problematic. In this article, we discuss issues related to the identification and preparation of Olympic athletes. We provide field-based data suggesting that an earlier onset and a higher volume of discipline-specific training and competition, and an extended involvement in institutional talent promotion programmes, during adolescence need not necessarily be associated with greater success in senior international elite sport. Next, we consider some of the promising methods that have been (recently) presented in the literature and applied in the field. Finally, implications for talent identification and promotion and directions for future research are highlighted.

Single vs. multiple sets of resistance exercise for muscle hypertrophy: a meta-analysis.

Krieger JW.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010-04 24(4):1150-9. Journal of Pure Power, Colorado Springs, CO, USA

Previous meta-analyses have compared the effects of single to multiple sets on strength, but analyses on muscle hypertrophy are lacking. The purpose of this study was to use multilevel meta-regression to compare the effects of single and multiple sets per exercise on muscle hypertrophy. The analysis comprised 55 effect sizes (ESs), nested within 19 treatment groups and 8 studies. Multiple sets were associated with a larger ES than a single set (difference = 0.10 +/- 0.04; confidence interval [CI]: 0.02, 0.19; p = 0.016). In a dose-response model, there was a trend for 2-3 sets per exercise to be associated with a greater ES than 1 set (difference = 0.09 +/- 0.05; CI: -0.02, 0.20; p = 0.09), and a trend for 4-6 sets per exercise to be associated with a greater ES than 1 set (difference = 0.20 +/- 0.11; CI: -0.04, 0.43; p = 0.096). Both of these trends were significant when considering permutation test p values (p < 0.01). There was no significant difference between 2-3 sets per exercise and 4-6 sets per exercise (difference = 0.10 +/- 0.10; CI: -0.09, 0.30; p = 0.29). There was a tendency for increasing ESs for an increasing number of sets (0.24 for 1 set, 0.34 for 2-3 sets, and 0.44 for 4-6 sets). Sensitivity analysis revealed no highly influential studies that affected the magnitude of the observed differences, but one study did slightly influence the level of significance and CI width. No evidence of publication bias was observed. In conclusion, multiple sets are associated with 40% greater hypertrophy-related ESs than 1 set, in both trained and untrained subjects.

Physiological monitoring of the Olympic athlete.

Davison RR, Van Someren KA, Jones AM.: Journal of Sports Sciences, 2009-11 27(13):1433-42. School of Life Sciences, Edinburgh Napier University, Edinburgh EH10 5DT, UK.

As the winning margin in Olympic competition is so small, there is a continuous quest for improvements in the preparation of athletes at this standard. Therefore, even the smallest physiological improvements that result from modifications in training strategy, preparation regime or ergogenic aids are potentially useful. Unfortunately, there is a lack of research data on elite competitors, which limits our interpretation of current literature to the elite sporting environment. This places extra responsibility on the physiologist to carefully consider the most appropriate physiological variables to monitor, the best protocols to assess those variables, and the accurate interpretation of the test results. In this paper, we address the key issues of ecological validity, measurement error, and interpretation for the most commonly monitored physiological variables. Where appropriate, we also indicate areas that would benefit from further research.

Percentile values for running sprint field tests in children ages 6-17 years: influence of weight status.

Castro-Piñero J, González-Montesinos JL, Keating XD, Mora J, Sjöström M, Ruiz JR.: Research Quarterly for Exercise and Sport, 2010-06 81(2):143-51. Department of Physical Education, University of Cadiz, Puerto Real, Spain.

The aim of this study was to provide percentile values for six different sprint tests in 2,708 Spanish children (1,234 girls) ages 6-17.9 years. We also examined the influence of weight status on sprint performance across age groups, with a focus on underweight and obese groups. We used the 20-m, 30-m, and 50-m running sprint standing start and running start tests to assess sprint performance. We calculated body mass index (BMI) using and categorized participants according to the BMI international cut-off for underweight, normal weight, overweight, and obese. Boys had significantly better scores than girls in all tests, except for the 30-m running sprint standing start and running start tests in the 6-7 year-old group. The underweight group had significantly better scores than their obese counterparts, whereas there were similar levels between underweight and normal weight individuals. The normal weight group showed a significantly better performance than their overweight and obese counterparts. Overweight boys had significantly better performance than their obese counterparts. In conclusion, the percentiles values of six running tests varied by age and gender The findings indicated that underweight youth did not have poorer sprint performance, and the obese group had lower scores than their leaner counterparts.

The influence of posture on transmission and absorption of vibration energy in whole body vibration exercise

Berschin G, Sommer HM.: Sportverletzung Sportschaden : Organ der Gesellschaft für Orthopädisch-Traumatologische Sportmedizin, 2010-03 24(1):36-9. Institut für Sportwissenschaft und Motologie, Abteilung Sportmedizin, Philipps-Universität Marburg, Marburg.

Muscle exercise using whole body vibration platforms is well known as an alternative physical exercise in therapy as well as in high performance sports. Various studies could show an effectiveness in particular to improve maximal strength and springiness. Using these platforms there is no consideration to posture although the damage potential of vibration stress i. e. on intervertebral discs is well-known. Therefore the effect of posture on the transmission and absorption of vibration loads in bipedal standing was examined in a study with 20 sport students. They were exposed to a whole body vibration load in bipedal standing at a vibration frequency of 25 Hz. The transmission of energy was measured at the head in different postural positions. An average transmission of 9 % was measured in spontaneous bipedal standing. It significantly decreased with gradual changes of posture. After 6 weeks posture conditioning exercise this effect was significantly improved. In conclusion different posture in bipedal standing implies not only different energy absorption but also different effects on muscle performance which can explain the partly inconsistent results after vibration exercise. In addition whole body vibration exercise in a prone or sitting position may increase the risk of overload and should be avoided because of reduced energy absorption capacity.

Work-rate of substitutes in elite soccer: a preliminary study.

Carling C, Espié V, Le Gall F, Bloomfield J, Jullien H.: Journal of Science and Medicine in Sport / Sports Medicine Australia, 2010, 13(2):253-5.Ecole des Métiers du Sport Professionnel, LOSC Lille Métropole Football Club, Centre de Formation, Domain de Luchin, Camphin-en-Pévèle, France.

The aim of this study was to investigate the work-rate of substitutes in professional soccer. A computerised player tracking system was used to assess the work-rates of second-half substitutes (11 midfielders and 14 forwards) in a French Ligue 1 club. Total distance, distance covered in five categories of movement intensity and recovery time between high-intensity efforts were evaluated. First- and second-half work-rates of the replaced players were compared. The performance of substitutes was compared to that of the players they replaced, to team-mates in the same position who remained on the pitch after the substitution and in relation to their habitual performances when starting games. No differences in work-rate between first- and second-halves were observed in all players who were substituted. In the second-half, a non-significant trend was observed in midfield substitutes who covered greater distances than the player they replaced whereas no differences were observed in forwards. Midfield substitutes covered a greater overall distance and distance at high-intensities (p<0.01) and had a lower recovery time between high-intensity efforts (p<0.01) compared to other midfield team-mates who remained on the pitch. Forwards covered less distance (p<0.01) in their first 10-min as a substitute compared to their habitual work-rate profile in the opening 10-min when starting matches while this finding was not observed in midfielders. These findings suggest that compared to midfield substitutes, forward substitutes did not utilise their full physical potential. Further investigation is warranted into the reasons behind this finding in order to optimise the work-rate contributions of forward substitutes.

The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial.

Meinhardt U, Nelson AE, Hansen JL, Birzniece V, Clifford D, Leung KC, Graham K, Ho KK.: Annals of Internal Medicine, 2010, 152(9):568-77. Garvan Institute of Medical Research and St Vincent's Hospital, Darlinghurst, New South Wales, Australia.

BACKGROUND: Growth hormone is widely abused by athletes, frequently with androgenic steroids. Its effects on performance are unclear. OBJECTIVE: To determine the effect of growth hormone alone or with testosterone on body composition and measures of performance. DESIGN: Randomized, placebo-controlled, blinded study of 8 weeks of treatment followed by a 6-week washout period. Randomization was computer-generated with concealed allocation. (Australian-New Zealand Clinical Trials Registry registration number: ACTRN012605000508673) SETTING: Clinical research facility in Sydney, Australia. PARTICIPANTS: 96 recreationally trained athletes (63 men and 33 women) with a mean age of 27.9 years (SD, 5.7). INTERVENTION: Men were randomly assigned to receive placebo, growth hormone (2 mg/d subcutaneously), testosterone (250 mg/wk intramuscularly), or combined treatments. Women were randomly assigned to receive either placebo or growth hormone (2 mg/d). MEASUREMENTS: Body composition variables (fat mass, lean body mass, extracellular water mass, and body cell mass) and physical performance variables (endurance [maximum oxygen consumption], strength [dead lift], power [jump height], and sprint capacity [Wingate value]). RESULTS: Body cell mass was correlated with all measures of performance at baseline. Growth hormone significantly reduced fat mass, increased lean body mass through an increase in extracellular water, and increased body cell mass in men when coadministered with testosterone. Growth hormone significantly increased sprint capacity, by 0.71 kJ (95% CI, 0.1 to 1.3 kJ; relative increase, 3.9% [CI, 0.0% to 7.7%]) in men and women combined and by 1.7 kJ (CI, 0.5 to 3.0 kJ; relative increase, 8.3% [CI, 3.0% to 13.6%]) when coadministered with testosterone to men; other performance measures did not significantly change. The increase in sprint capacity was not maintained 6 weeks after discontinuation of the drug. LIMITATIONS: Growth hormone dosage may have been lower than that used covertly by competitive athletes. The athletic significance of the observed improvements in sprint capacity is unclear, and the study was too small to draw conclusions about safety. CONCLUSION: Growth hormone supplementation influenced body composition and increased sprint capacity when administered alone and in combination wi

The physical and physiological demands of basketball training and competition.

Montgomery PG, Pyne DB, Minahan CL.: International Journal of sports Physiology and Performance

2010, 5(1):75-86. Department of Physiology, Australian Institute of Sport, Canberra, Australia. PURPOSE: To characterize the physical and physiological responses during different basketball practice drills and games. METHODS: Male basketball players (n=11; 19.1+/-2.1 y, 1.91+/-0.09 m, 87.9+/-15.1 kg; mean+/-SD) completed offensive and defensive practice drills, half court 5on5 scrimmage play, and competitive games. Heart rate, VO2, and triaxial accelerometer data (physical demand) were normalized for individual participation time. Data were log-transformed and differences between drills and games standardized for interpretation of magnitudes and reported with the effect size (ES) statistic. RESULTS: There was no substantial difference in the physical or physiological variables between offensive and defensive drills; physical load (9.5%; 90% confidence limits+/-45); mean heart rate (-2.4%; +/-4.2); peak heart rate (-0.9%; +/-3.4); and VO2 (-5.7%; +/-9.1). Physical load was moderately greater in game play compared with a 5on5 scrimmage (85.2%; +/-40.5); with a higher mean heart rate (12.4%; +/-5.4). The oxygen demand for live play was substantially larger than 5on5 (30.6%; +/-15.6). CONCLUSIONS: Defensive and offensive drills during basketball practice have similar physiological responses and physical demand. Live play is substantially more demanding than a 5on5 scrimmage in both physical and physiological attributes. Accelerometers and predicted oxygen cost from heart rate monitoring systems are useful for differentiating the practice and competition demands of basketball.

Precooling can prevent the reduction of self-paced exercise intensity in the heat.

Duffield R, Green R, Castle P, Maxwell N.: Medicine and Science in Sports and Exercise, 2010, 42(3):577-84. States School of Human Movement Studies, Charles Sturt University, Bathurst, New South Wales, Australia.

PURPOSE: This study investigated the effects of precooling on performance and pacing during self-paced endurance cycling in the heat and, further, the effects of cooling on contractile function as a mechanism for performance changes. METHODS: After familiarization, eight male cyclists performed two randomized 40-min time trials on a cycle ergometer in 33 degrees C. Before the time trials, participants underwent either a 20-min lower-body cold-water immersion procedure or no cooling intervention. Before and after the intervention and the time trial, voluntary force (maximal voluntary contraction (MVC)), superimposed force (SIF), evoked twitch force (peak twitch force (Pf)), muscle temperature, and blood metabolites were measured. Further, measures of core and skin temperature and HR were recorded before, during, and after cooling and time trial. RESULTS: Results indicated that cycling performance was improved with precooling (198 +/- 25 vs 178 +/- 26 W for precooling and control, respectively; P = 0.05). Although core, muscle, skin, and mean body temperatures were lower in the cooling condition until the 20th minute (P < 0.05), performance did not differ until the last 10 min of the time trial, by which time no differences in physiological measures were present. Further, while MVC and SIF were reduced postexercise in both conditions, MVC, SIF, and Pf were not different between conditions preexercise or postexercise. CONCLUSION: In conclusion, a precooling intervention improved self-paced endurance exercise; however, the improvement in performance became evident after measured physiological differences induced by precooling had dissipated. Further, the lack of difference between conditions in MVC, SIF, or Pf indicates that improvements in performance did not result from an improvement in contractile function, suggesting that improvements may result from other mechanisms such as muscle recruitment.

Whole-body vibration training increases vertical jump height in a dance population.

Wyon M, Guinan D, Hawkey A.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):866-70. Research Center for Sport, Exercise and Performance, School of Sport, Performing Arts and Leisure, University of Wolverhampton, United Kingdom.

Whole-body vibration (WBV) training has gained popularity with the strength and conditioning environment. Previous research reported improvements in strength and power after WBV interventions in untrained individuals with little hypertrophical development of the muscles, suggesting that the improvements are because of neuromuscular adaptations. The present intervention study recruited moderately trained individuals that have jumping as integral to their training. Participants were randomly allocated to an intervention or control group. The intervention group was exposed to WBV at 35 Hz for 5 minutes twice a week, whereas the control group was exposed to a similar isometric contraction stress. Results indicated that after a 6-week intervention, vertical jump height increased significantly (p < 0.05) in the intervention group than in the control group. The study concluded that WBV was able to maintain vertical jump height with very little intervention time (10 minutes a week) and therefore should be considered as an intervention form for maintaining jump performance.

Effect of air pollution on marathon running performance.

Marr LC, Ely MR.: Medicine and Science in Sports and Exercise, 2010, 42(3):585-91. Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061, USA.

Before the 2008 Olympic Games, there was concern that air pollution in Beijing would affect the performance of marathon runners. Air pollutant concentrations during marathon running and their effect on performance have not been reported. Evidence suggests that the lung function of females may be more susceptible than that of males to air pollution, but it is uncertain if this translates to decreased marathon performance. PURPOSE: The purposes of this study were to 1) describe ambient air pollutant concentrations present during major US marathons, 2) quantify performance decrements associated with air pollutants, and 3) examine potential sex difference in performance related to air pollutants. METHODS: Marathon race results, weather data, and air pollutant concentrations were obtained for seven marathons for 8-28 yr. The top three male and female finishing times were compared with the course record and contrasted with air pollutant levels and wet bulb globe temperature (WBGT). A WBGT-adjusted performance decrement was calculated, and regression analysis was used to quantify performance decrements associated with pollutants. RESULTS: The air pollutant concentrations of carbon monoxide, ozone, particulate matter smaller than 10 microm (PM(10)), PM(2.5), nitrogen dioxide, and sulfur dioxide ranged from 0 to 5.9 ppm, from 0 to 0.07 ppm, from 4.5 to 41.0 microg x m(-3), from 2.8 to 42.0 microg x m(-3), from 0 to 0.06 ppm, and from 0 to 0.05 ppm, respectively. After adjusting for WBGT-associated performance decrements, only PM(10) was associated with decrements in performance of women. For every 10-microg x m(-3) increase in PM(10), performance can be expected to decrease by 1.4%. CONCLUSIONS: The concentrations of air pollution present during marathons rarely exceed health-based national standards and levels known to affect lung function in laboratory situations. Regardless, PM(10) was significantly correlated with performance of women marathon runners.

Training volume and personal best time in marathon, not anthropometric parameters, are associated with performance in male 100-km ultrarunners.

Knechtle B, Wirth A, Knechtle P, Rosemann T.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):604-9. Gesundheitszentrum St. Gallen, St. Gallen, Switzerland.

We investigated the relation between selected anthropometric and training variables and the personal best time in a marathon with total race time in 66 Caucasian male nonprofessional ultrarunners in a 100-km run. In the multiple linear regression analysis, the average weekly training volume in kilometers (r2 = 0.224, p < 0.01) and the personal best time in a marathon (r2 = 0.334, p 0.05). We conclude that high training volume and a fast time in a marathon were more important for a fast race time in male 100-km runners than any of the determined anthropometric variables.

Static stretching does not impair performance in active middle-aged adults.

Handrakis JP, Southard VN, Abreu JM, Aloisa M, Doyen MR, Echevarria LM, Hwang H, Samuels C, Venegas SA, Douris PC.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):825-30.NYIT-School of Health Professions, Behavioral and Life Sciences, Old Westbury, New York, USA.

Recent investigations with young, healthy adult subjects suggest that static stretching before activity decreases performance and should, therefore, be avoided. The purpose of this study was to assess the effects of an acute static stretching protocol on balance and jump/hop performance in active middle-aged adults. Ten subjects (6 men and 4 women aged 40-60 yr) from a martial arts school volunteered to take part in this research study. This was a repeated measures design. Subjects who stretched for 10 minutes using a 30-second hold during 1 session sat quietly for 10 minutes during the alternate session. Sessions were randomly assigned. The following dependent variables were compared: Dynamic Stability Index (DSI) for single-leg dynamic balance (smaller DSI = improved balance); distances for broad jump, single hop, triple hop, and crossover hop; elapsed time for a 6-m timed hop. Group means for balance were significantly different between the stretch and no-stretch conditions (3.5 +/- 0.7 vs. 4.3 +/- 1.4 DSI, respectively; p < 0.05). No significant differences were found between the group means of the stretch and no-stretch conditions for the dependent measures of broad jump, single hop, triple hop, crossover hop, and 6-m timed hop performance. Ten minutes of acute static stretching enhances dynamic balance and does not affect jump/hop performance in active middle-aged adults. Static stretching should be included before competition and before exercise in fitness programs of active middle-aged adults.

Reliability and factorial validity of agility tests for soccer players.

Sporis G, Jukic I, Milanovic L, Vucetic V.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):679-86. Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia.

The purpose of this study was to evaluate the reliability and factorial validity of agility tests used in soccer. One hundred fifty (n = 150), elite, male, junior soccer players, members of the First Junior League Team, volunteered to participate in the study. The slalom test (ST) sprint 4 x 5 m (S4 x 5) and sprint 9-3-6-3-6-9 m with 180 degree turns (S180 degrees) tests had a greater reliability coefficient (alpha = 0.992, 0.979, and 0.976), whereas the within-subject variation ranged between 2.9 and 5.6%. The mentioned 6 agility tests resulted in the extraction of 2 significant components. The S4 x 5 test had the lowest correlation coefficient with the first component (r = 0.38), whereas the correlation coefficients of the other 5 agility tests were higher than 0.63. The T-test (TT) showed statistically significant differences between the defenders and midfielders (p < 0.05) and between the defenders and attackers (p < 0.05). Statistical significant differences were determined between the attackers and defenders in the sprint 9-3-6-3-9 m with backward and forward running (SBF) and p < 0.05. It can be concluded that of the 6 agility tests used in this study, the SBF, TT, and S180 degrees are the most reliable and valid tests for estimating the agility of soccer players. According to the results of the study, the TT proved to be the most appropriate for estimating the agility of defenders, the SBF, and S180 degrees for estimating the agility of midfielders, whereas the S4 x 5 test can be used for estimating the agility of attackers.

Effect of preseason concurrent muscular strength and high-intensity interval training in professional soccer players.

Wong PL, Chaouachi A, Chamari K, Dellal A, Wisloff U.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):653-60. Department of Physical Education, Hong Kong Baptist University, Hong Kong.

This study examined the effect of concurrent muscular strength and high-intensity running interval training on professional soccer players' explosive performances and aerobic endurance. Thirty-nine players participated in the study, where both the experimental group (EG, n = 20) and control group (CG, n = 19) participated in 8 weeks of regular soccer training, with the EG receiving additional muscular strength and high-intensity interval training twice per week throughout. Muscular strength training consisted of 4 sets of 6RM (repetition maximum) of high-pull, jump squat, bench press, back half squat, and chin-up exercises. The high-intensity interval training consisted of 16 intervals each of 15-second sprints at 120% of individual maximal aerobic speed interspersed with 15 seconds of rest. EG significantly increased (p < or = 0.05) 1RM back half squat and bench press but showed no changes in body mass. Within-subject improvement was significantly higher (p < or = 0.01) in the EG compared with the CG for vertical jump height, 10-m and 30-m sprint times, distances covered in the Yo-Yo Intermittent Recovery Test and maximal aerobic speed test, and maximal aerobic speed. High-intensity interval running can be concurrently performed with high load muscular strength training to enhance soccer players' explosive performances and aerobic endurance.

Effects of 12-week on-field combined strength and power training on physical performance among U-14 young soccer players.

Wong PL, Chamari K, Wisløff U.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):644-52 Department of Physical Education, Hong Kong Baptist. University, Hong Kong.

This study examined the effects of on-field combined strength and power training (CSPT) on physical performance among U-14 young soccer players. Players were assigned to experimental (EG, n = 28) and control groups (CG, n = 23). Both groups underwent preseason soccer training for 12 weeks. EG performed CSPT twice a week, which consisted of strength and power exercises that trained the major muscles of the core, upper, and lower body. CSPT significantly (p < 0.05) improved vertical jump height, ball-shooting speed, 10 m and 30 m sprint times, Yo-Yo intermittent endurance run (YYIER), and reduced submaximal running cost (RC). CSPT had moderate effect on vertical jump, ball-shooting, 30 m sprint, and YYIER, small effect on 10 m sprint, RC, and maximal oxygen uptake. YYIER had significant (p < 0.05) correlations with 10 m (r = -0.47) and 30 m (r = -0.43) sprint times, ball-shooting speed (r = 0.51), and vertical jump (r = 0.34). The CSPT can be performed together with soccer training with no concomitant interference on aerobic capacity and with improved explosive performances. In addition, it is suggested that CSPT be performed during the preseason period rather than in-season to avoid insufficient recovery/rest or overtraining.

Effects of low- and high-volume stretching on bench press performance in collegiate football players.

Molacek ZD, Conley DS, Evetovich TK, Hinnerichs KR.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):711-6. Department of Health, Human Performance and Sport, Human Performance Laboratory, Wayne State College, Wayne, Nebraska, USA.

The purpose of this study was to determine the effects of acute low- and high-volume static and proprioceptive neuromuscular facilitation (PNF) stretching on 1-repetition maximum (1RM) bench press. Fifteen healthy male National Collegiate Athletic Association Division II football players (age: 19.9 +/- 1.1 years; weight: 98.89 +/- 13.39 kg; height: 184.2 +/- 5.7 cm; body composition: 14.6 +/- 7.4%; and 1RM bench press: 129.7 +/- 3.3 kg) volunteered to participate in the study. Subjects completed 5 different stretching protocols integrated with a 1RM dynamic warm-up routine followed by 1RM testing in randomly assigned order. The protocols included (a) nonstretching (NS), (b) low-volume PNF stretching (LVPNFS), (c) high-volume PNF stretching (HVPNFS), (d) low-volume static stretching (LVSS), and (d) high-volume static stretching (HVSS). Two and 5 sets of stretching were completed for the low- and high-volume protocols, respectively. The stretching protocols targeted triceps and chest/shoulder muscle groups using 2 separate exercises. There were no significant differences in 1RM bench press performance (p > 0.05) among any of the stretching protocols NS (129.7 +/- 3.3 kg), LVPNFS (128.9 +/- 3.8 kg), HVPNFS (128.3 +/- 3.7 kg), LVSS (129.7 +/- 3.7 kg), and HVSS (128.2 +/- 3.7 kg). We conclude that low- and high-volume PNF and static stretching have no significant acute effect on 1RM bench press in resistance-trained collegiate football players. This suggests that resistance-trained athletes can include either (a) a dynamic warm-up with no stretching or (b) a dynamic warm-up in concert with low- or high-volume static or PNF flexibility exercises before maximal upper body isotonic resistance-training lifts, if adequate rest is allowed before performance.

Effect of squatting on sprinting performance and repeated exposure to complex training in male rugby

players. Comyns TM, Harrison AJ, Hennessy LK.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(3):610-8. Strength and Conditioning Department, Irish Rugby Football Union, Dublin 4, Ireland.

This study was undertaken to examine the effect of a heavy weight training exercise on sprinting performance and on the effect of repeated exposure to a complex training protocol. Eleven male rugby union players (age 20.9 +/- 3.1 years) participated in the study, which involved 5 separate testing sessions. Back squat 3 repetition maximum (3RM) was established in session 1. Sessions 2-5 were identical and involved the subjects completing a 30-m sprint before and after a 3RM back squat protocol. Four minutes of rest was given between the back squatting and the posttest 30-m sprint. All sprint trials were measured with a laser measurement device (LAVEG, Jenoptik, Jena, Germany). Sprint time and instantaneous, average, and maximum velocity were the dependent variables. The criterion for significance was set at an alpha level of p > or = 0.05. No significant improvement was evident for any of the testing sessions (p > or = 0.05). In session 1, there was a significant increase in 30-m time and a significant reduction in average 30-m velocity and maximum velocity (p < 0.05). The expected benefits in sprinting may not have been realized because of intra and intersubject variations in sprint technique. The session x phase interaction revealed a significant improvement in the pre to posttest changes in instantaneous velocity at 20 m (p = 0.035) and 30 m (p = 0.036) from session 1 to session 4. This indicates that the rugby players may be able to learn to apply the potentiation effects of complex training. From a practical perspective, players may need repeated exposure to this training modality to gain benefit from it, and this should be reflected in program planning.

Is hypoxia training good for muscles and exercise performance?

Vogt M, Hoppeler H.: Progress in Cardiovascular Diseases, 2010 May-Jun 52(6):525-33. Department of Anatomy, University of Bern, CH-3012 Bern, Switzerland.

Altitude training has become very popular among athletes as a means to further increase exercise performance at sea level or to acclimatize to competition at altitude. Several approaches have evolved during the last few decades, with "live high-train low" and "live low-train high" being the most popular. This review focuses on functional, muscular, and practical aspects derived from extensive research on the "live low-train high" approach. According to this, subjects train in hypoxia but remain under normoxia for the rest of the time. It has been reasoned that exercising in hypoxia could increase the training stimulus. Hypoxia training studies published in the past have varied considerably in altitude (2300-5700 m) and training duration (10 days to 8 weeks) and the fitness of the subjects. The evidence from muscle structural, biochemical, and molecular findings point to a specific role of hypoxia in endurance training. However, based on the available performance capacity data such as maximal oxygen uptake (Vo(2)max) and (maximal) power output, hypoxia as a supplement to training is not consistently found to be advantageous for performance at sea level. Stronger evidence exists for benefits of hypoxic training on performance at altitude. "Live low-train high" may thus be considered when altitude acclimatization is not an option. In addition, the complex pattern of gene expression adaptations induced by supplemental training in hypoxia, but not normoxia, suggest that muscle tissue specifically responds to hypoxia. Whether and to what degree these gene expression changes translate into significant changes in protein concentrations that are ultimately responsible for observable structural or functional phenotypes remains open. It is conceivable that the global functional markers such as Vo(2)max and (maximal) power output are too coarse to detect more subtle changes that might still be functionally relevant, at least to high-level athletes.

Variation in human performance in the hypoxic mountain environment.

Martin DS, Levett DZ, Grocott MP, Montgomery HE.: Experimental Physiology, 2010, 95(3):463-70 UCL Institute for Human Health and Performance, 2nd Floor, Charterhouse Building, UCL Archway Campus, Highgate Hill, Archway, London N19 5LW, UK.

Ascent to altitude is associated with a fall in barometric pressure, and with it a decline in the partial pressure of atmospheric (and thus alveolar) oxygen. As a result, a variety of adaptive physiological processes are engaged to mitigate the fall in tissue convective oxygen delivery which might otherwise occur. The magnitude and nature of such changes is also modified with time, a process known as acclimatization. However, other phenomena are at work; the ability to perform physical work at altitude falls in a manner which is not wholly related to changes in arterial oxygen content. Indeed, alterations in local skeletal muscle blood flow and metabolism may play an axial role. Thus, for those who are not native to high altitude, the ability to compete at altitude is likely to be impaired. The magnitude of such impairment in performance, however, differs greatly between individuals, and it seems that genetic variation underpins much of this difference. The identification of the relevant genetic elements is in its infancy in humans, but ongoing work is likely to help us gain an increasing understanding of how humans adapt to altitude and to develop mitigating interventions.

Watching a previous victory produces an increase in testosterone among elite hockey players.

Carré JM, Putnam SK.: Psychoneuroendocrinology , 2010, 35(3):475-9. Department of Psychology, Brock University, St Catharines, Ontario, Canada.

Previous research indicates that testosterone concentrations are highly responsive to human competitive interactions and that winners have elevated testosterone concentrations relative to losers. Also, there is some evidence that simply observing others compete can have a similar effect on the endocrine system. Here, in two studies, we examined the extent to which elite male hockey players would demonstrate an increase in testosterone concentrations after watching themselves engaged in a previous successful competitive interaction. Results indicated that watching a previous victory produced a significant increase in testosterone concentrations (42-44% increase), whereas watching a previous defeat or a neutral video did not produce a significant change in testosterone (17% and 6%, respectively). Given that natural fluctuations in testosterone have been shown to influence future competitive and aggressive behaviours, the current studies may have important practical implications for individuals involved in competitive sports.

Young tennis players and balance performance.

Malliou VJ, Beneka AG, Gioftsidou AF, Malliou PK, Kallistratos E, Pafis GK, Katsikas CA, Douvis S.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 20100, 24(2):389-93. Department of Physical Education & Sports Science, National & Kapodistrian University of Athens, Athens, Greece.

The purpose of the present study was to investigate the effect of a tennis training session on the balance performance of young tennis players. The study was conducted on 36 elite tennis players (age 14 +/- 2 years; body mass 55 +/- 6 kg; body height 165 +/- 6 cm; mean +/- SD) participating in the national young tennis championship. Balance performance was assessed before and immediately after a tennis training session (pre-training and post-training, respectively). The balance assessment was performed with 2 different balance boards and the Biodex Stability System. In addition, dynamometric measurements of peak isokinetic moment in the knee flexors and extensors were performed pre and post tennis training session, to quantify the degree of muscle fatigue induced by the tennis training session. One-way analysis of variance with repeated measures was used to test for differences in balance performance and in isokinetic performance between pre and post tennis training session. The data analysis revealed no significant differences (p > 0.05) in balance performance, whereas there were significant differences in knee joint moment production between pre and post tennis training measures. Although the tennis training session of the present study had no significant effect (p > 0.05) on any of the balance performance indicators examined, there was a decline in balance performance, which suggests that different level of fatigue for an extended period (games) will have greater effect on balance performance. It is suggested that a tennis-specific balance exercise program should be included in the tennis training session.

Upper-body strength and power changes during a football season.

Hrysomallis C.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(2):557-9.Centre for Ageing, Rehabilitation, Exercise and Sport, Victoria University, Melbourne, Australia.

There are different football codes played around the world, and most of them involve contact and collision during competition. Upper-body strength and power are important for success in American football, rugby league, rugby union, and Australian football. The goal of the preseason Conditioning program is usually to maximize muscular fitness before the competitive season. The in-season program is usually intended to maintain the preseason gains, but it is unclear as to whether the preseason levels of upper-body strength and power can be maintained or even increased during the in-season. The aims of this review were to investigate and identify any general trends in the training programs and results of football studies that have monitored levels of upper-body strength and power preseason, in-season, or postseason. Six studies were identified: 4 involved American college football and the other 2 involved rugby codes and included professional athletes. For most studies, resistance training was conducted 4 times per week preseason and reduced to 2 times per week in-season. The bench press exercise was used as the measure of upper-body strength, and only one of the rugby studies measured upper-body power and used bench press throws. It was found that upper-body strength or power could be maintained or even increased past the mid-season point, but this may be dependent on age, football code, and level of play. At the end of the season, decreases were starting to be reported but only for 2 studies. Surprisingly, an increase in strength was reported postseason for college rugby league players. From the available information, it seems that an in-season periodized program that includes high-intensity resistance training may optimize strength and power ability during the in-season, but more Research is required that compares the effectiveness of Conditioning programs with varying combinations of training variables.

Early-phase resistance training strength gains in novice lifters are enhanced by doing static stretching.

Kokkonen J, Nelson AG, Tarawhiti T, Buckingham P, Winchester JB.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(2):502-6. Exercise and Sport Science Department, Brigham Young University-Hawaii, Laie, Hawaii, USA.

This study investigated differences in lower-body strength improvements when using standard progressive resistance training (WT) vs. the same progressive resistance training combined with static stretching exercises (WT + ST). Thirty-two college students (16 women and 16 men) were pair matched according to sex and knee extension 1 repetition maximum (1RM). One person from each pair was randomly assigned to WT and the other to WT + ST. WT did 3 sets of 6 repetitions of knee extension, knee flexion, and leg press 3 days per week for 8 weeks with weekly increases in the weight lifted. The WT + ST group performed the same lifting program as the WT group along with static stretching exercises designed to stretch the hip, thigh, and calf muscle groups. Stretching exercise sessions were done twice a week for 30 minutes during the 8-week period. WT significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 12, 14, and 9%, respectively. WT + ST, on the other hand, significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 16, 27, and 31, respectively. In addition, the WT + ST group had significantly greater knee extension and leg press gains (p < 0.05) than the WT group. Based on results of this study, it is recommended that to maximize strength gains in the early phase of training, novice lifters should include static stretching exercises to their resistance training programs.

Game-induced fatigue patterns in elite female soccer.

Krustrup P, Zebis M, Jensen JM, Mohr M.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(2):437-41.Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.

The purpose was to examine the fatigue pattern of elite female soccer players after competitive games. Soccer players (n = 23) from the Danish women Premier League performed a countermovement vertical jump test, a repeated 30-m sprint test, and the Yo-Yo intermittent endurance level 2 (Yo-Yo IE2) test at rested state and after a competitive game. Average heart rate during the game was 86 +/- 1% of maximal heart rate with no differences between halves. Blood lactate was 5.1 +/- 0.5 mmol.L after the first half, which was higher (p < 0.05) than after the second half (2.7 +/- 0.4 mmol.L). Yo-Yo IE2 performance was 484 +/- 50 m after the game, which was 62% lower (p < 0.05) than at rested state (1,265 +/- 133 m). Average sprinting time of three 30-m sprints was 5.06 +/- 0.06 seconds after the game, which was 4% slower (p < 0.05) than at rest (4.86 +/- 0.06 seconds). No game-induced effect was observed on vertical jump performance. Significant inverse correlations were observed between Yo-Yo IE2 test performance and fatigue index during the repeated sprint test both at rest (r = -0.76, p < 0.05) and after the game (r = -0.66, p < 0.05). The study demonstrates that the type of fatigue that occurs after a female soccer game does cause marked impairment in intense intermittent exercise and repeated sprint performance but does not affect vertical jump performance. These findings support the notion that decrements in distance covered by sprinting and high-speed running toward the end of elite female games are caused by fatigue.

Effects of simulated and real altitude exposure in elite swimmers.

Robertson EY, Aughey RJ, Anson JM, Hopkins WG, Pyne DB.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(2):487-93. Department of Physiology, Australian Institute of Sport, Canberra, Australia.

The effect of repeated exposures to natural and simulated moderate altitude on Physiology and competitive performance of elite athletes warrants further investigation. This study quantified changes in hemoglobin mass, performance tests, and competitive performance of elite swimmers undertaking a coach-prescribed program of natural and simulated altitude training. Nine swimmers (age 21.1 +/- 1.4 years, mean +/- SD) completed up to four 2-week blocks of combined living and training at moderate natural altitude (1,350 m) and simulated live high-train low (2,600-600 m) altitude exposure between 2 National Championships. Changes in hemoglobin mass (Hbmass), 4-mM lactate threshold velocity, and 2,000 m time trial were measured. Competition performance of these swimmers was compared with that of 9 similarly trained swimmers (21.1 +/- 4.1 years) who undertook no altitude training. Each 2-week altitude block on average produced the following improvements: Hbmass, 0.9% (90% confidence limits, +/-0.8%); 4-mM lactate threshold velocity, 0.9% (+/-0.8%); and 2,000 m time trial performance, 1.2% (+/-1.6%). The increases in Hbmass had a moderate correlation with time trial performance (r = 0.47; +/-0.41) but an unclear correlation with lactate threshold velocity (r = -0.23; +/-0.48). The altitude group did not swim faster at National Championships compared with swimmers who did not receive any altitude exposure, the difference between the groups was not substantial (-0.5%; +/-1.0%). A coach-prescribed program of repeated altitude training and exposure elicited modest changes in Physiology but did not substantially improve competition performance of elite swimmers. Sports should investigate the efficacy of their altitude training program to justify the investment.

Acute alcohol consumption aggravates the decline in muscle performance following strenuous eccentric exercise.

Barnes MJ, Mündel T, Stannard SR.: Journal of Science and Medicine in Sport / Sports Medicine Australia, 2010, 13(1):189-93.Institute of Food, Nutrition, and Human Health, Massey University, Palmerston North, New Zealand.

This study investigated the effects of acute moderate alcohol intake on muscular performance during recovery from eccentric exercise-induced muscle damage. Eleven healthy males performed 300 maximal eccentric contractions of the quadriceps muscles of one leg on an isokinetic dynamometer. They then consumed a beverage containing 1g/kg bodyweight ethanol (as vodka and orange juice) (ALC). On another occasion they performed an equivalent bout of eccentric exercise on the contralateral leg after which they consumed an isocaloric quantity of orange juice (OJ). Measurement of maximal isokinetic (concentric and eccentric) and isometric torque produced across the knee, plasma creatine kinase (CK) concentrations and muscle soreness were made before and at 36 and 60h following each exercise bout. All measures of muscle performance were significantly reduced at 36 and 60h post-exercise compared to pre-exercise measures (all p0.05). These results indicate that consumption of even moderate amounts of alcohol following eccentric-based exercise magnifies the normally observed losses in dynamic and static strength. Therefore, to minimise exercise related losses in muscle function and expedite recovery, participants in sports involving eccentric muscle work should avoid alcohol-containing beverages in the post-event period.

Neuromuscular fatigue induced by an isotonic heavy-resistance loading protocol in knee extensors.

Walker S, Peltonen J, Ahtiainen JP, Avela J, Hakkinen K.: Journal of Sports Sciences, 2009, 27(12):1271-9. Department of Biology of Physical Activity, University of Jyvaskyla, Jyvaskyla, Finland.

The main aim of this study was to assess neuromuscular fatigue during a typical high-load, low-repetition loading protocol. Muscle stimulations were used to assess maximum voluntary contraction, resting single- and double-pulse twitch characteristics, and superimposed double-pulse twitch force (used to calculate voluntary activation) before and after an acute knee extension loading protocol. In our participants, who had previous resistance training experience, the mean voluntary activation level was 96.2% in an unfatigued state. Maximum voluntary contraction (-11.8%), resting double-pulse twitch force (-10.6%), and voluntary activation (-2.1%) were markedly decreased as a consequence of loading (P < 0.05). In addition, although potentiated twitch characteristics were observed during the loading protocol, this was short-lived, as fatigue surpassed the potentiation mechanisms. Our results show that both central and peripheral mechanisms contributed to neuromuscular fatigue during the present loading protocol.

The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial.

Meinhardt U, Nelson AE, Hansen JL, Birzniece V, Clifford D, Leung KC, Graham K, Ho KK.: Annals of Internal Medicine, 20100504 152(9):568-77. Garvan Institute of Medical Research and St Vincent's Hospital, Darlinghurst, New South Wales, Australia.

Background: Growth hormone is widely abused by athletes, frequently with androgenic steroids. Its effects on performance are unclear. Objective: To determine the effect of growth hormone alone or with testosterone on body composition and measures of performance. Design: Randomized, placebo-controlled, blinded study of 8 weeks of treatment followed by a 6-week washout period. Randomization was computer-generated with concealed allocation. (Australian-New Zealand Clinical Trials Registry registration number: ACTRN012605000508673) Setting: Clinical Research facility in Sydney, Australia. Participants: 96 recreationally trained athletes (63 men and 33 women) with a mean age of 27.9 years (SD, 5.7). Intervention: Men were randomly assigned to receive placebo, growth hormone (2 mg/d subcutaneously), testosterone (250 mg/wk intramuscularly), or combined treatments. Women were randomly assigned to receive either placebo or growth hormone (2 mg/d). MEASUREMENTS: Body composition variables (fat mass, lean body mass, extracellular water mass, and body cell mass) and physical performance variables (endurance [maximum oxygen consumption], Strength [dead lift], power [jump height], and sprint capacity [Wingate value]). Results: Body cell mass was correlated with all measures of performance at baseline. Growth hormone significantly reduced fat mass, increased lean body mass through an increase in extracellular water, and increased body cell mass in men when coadministered with testosterone. Growth hormone significantly increased sprint capacity, by 0.71 kJ (95% CI, 0.1 to 1.3 kJ; relative increase, 3.9% [CI, 0.0% to 7.7%]) in men and women combined and by 1.7 kJ (CI, 0.5 to 3.0 kJ; relative increase, 8.3% [CI, 3.0% to 13.6%]) when coadministered with testosterone to men; other performance measures did not significantly change. The increase in sprint capacity was not maintained 6 weeks after discontinuation of the drug. LIMITATIONS: Growth hormone dosage may have been lower than that used covertly by competitive athletes. The athletic significance of the observed improvements in sprint capacity is unclear, and the study was too small to draw conclusions about safety. Conclusions: Growth hormone supplementation influenced body composition and increased sprint capacity when administered alone and in combination wi

The physical and physiological demands of basketball training and competition.

Montgomery PG, Pyne DB, Minahan CL, International Journal of Sports Physiology and Performance

201003 5(1):75-86. Department of Physiology, Australian Institute of Sport, Canberra, Australia.

Purpose: To characterize the physical and physiological responses during different basketball practice drills and games. Methods: Male basketball players (n=11; 19.1+/-2.1 y, 1.91+/-0.09 m, 87.9+/-15.1 kg; mean+/-SD) completed offensive and defensive practice drills, half court 5on5 scrimmage play, and competitive games. Heart rate, VO2, and triaxial accelerometer data (physical demand) were normalized for individual participation time. Data were log-transformed and differences between drills and games standardized for interpretation of magnitudes and reported with the effect size (ES) statistic. Results: There was no substantial difference in the physical or physiological variables between offensive and defensive drills; physical load (9.5%; 90% confidence limits+/-45); mean heart rate (-2.4%; +/-4.2); peak heart rate (-0.9%; +/-3.4); and VO2 (-5.7%; +/-9.1). Physical load was moderately greater in game play compared with a 5on5 scrimmage (85.2%; +/-40.5); with a higher mean heart rate (12.4%; +/-5.4). The oxygen demand for live play was substantially larger than 5on5 (30.6%; +/-15.6). Conclusions : Defensive and offensive drills during basketball practice have similar physiological responses and physical demand. Live play is substantially more demanding than a 5on5 scrimmage in both physical and physiological attributes. Accelerometers and predicted oxygen cost from heart rate monitoring systems are useful for differentiating the practice and competition demands of basketball.

Precooling can prevent the reduction of self-paced exercise intensity in the heat.

Duffield R, Green R, Castle P, Maxwell N.: Medicine and Science in Sports and Exercise, 201003 42(3):577-84. School of Human Movement Studies, Charles Sturt University, Bathurst, New South Wales, Australia.

Purpose: This study investigated the effects of precooling on performance and pacing during self-paced endurance cycling in the heat and, further, the effects of cooling on contractile function as a mechanism for performance changes. Methods: After familiarization, eight male cyclists performed two randomized 40-min time trials on a cycle ergometer in 33 degrees C. Before the time trials, participants underwent either a 20-min lower-body cold-water immersion procedure or no cooling intervention. Before and after the intervention and the time trial, voluntary force (maximal voluntary contraction (MVC)), superimposed force (SIF), evoked twitch force (peak twitch force (Pf)), muscle temperature, and blood metabolites were measured. Further, measures of core and skin temperature and HR were recorded before, during, and after cooling and time trial. Results: Results indicated that cycling performance was improved with precooling (198 +/- 25 vs 178 +/- 26 W for precooling and control, respectively; P = 0.05). Although core, muscle, skin, and mean body temperatures were lower in the cooling condition until the 20th minute (P < 0.05), performance did not differ until the last 10 min of the time trial, by which time no differences in physiological measures were present. Further, while MVC and SIF were reduced postexercise in both conditions, MVC, SIF, and Pf were not different between conditions preexercise or postexercise. Conclusions: In conclusion, a precooling intervention improved self-paced endurance exercise; however, the improvement in performance became evident after measured physiological differences induced by precooling had dissipated. Further, the lack of difference between conditions in MVC, SIF, or Pf indicates that improvements in performance did not result from an improvement in contractile function, suggesting that improvements may result from other mechanisms such as muscle recruitment.

Whole-body vibration training increases vertical jump height in a dance population.

Wyon M, Guinan D, Hawkey A.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):866-70 . Research Center for Sport, Exercise and Performance, School of Sport, Performing Arts and Leisure, University of Wolverhampton, United Kingdom.

Whole-body vibration (WBV) training has gained popularity with the Strength and Conditioning environment. Previous Research reported improvements in Strength and power after WBV interventions in untrained individuals with little hypertrophical development of the muscles, suggesting that the improvements are because of neuromuscular adaptations. The present intervention study recruited moderately trained individuals that have jumping as integral to their training. Participants were randomly allocated to an intervention or control group. The intervention group was exposed to WBV at 35 Hz for 5 minutes twice a week, whereas the control group was exposed to a similar isometric contraction stress. Results indicated that after a 6-week intervention, vertical jump height increased significantly (p < 0.05) in the intervention group than in the control group. The study concluded that WBV was able to maintain vertical jump height with very little intervention time (10 minutes a week) and therefore should be considered as an intervention form for maintaining jump performance.

Effect of air pollution on marathon running performance.

Marr LC, Ely MR.: Medicine and Science in Sports and Exercise, 201003 42(3):585-91. Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061, USA.

Before the 2008 Olympic Games, there was concern that air pollution in Beijing would affect the performance of marathon runners. Air pollutant concentrations during marathon running and their effect on performance have not been reported. Evidence suggests that the lung function of females may be more susceptible than that of males to air pollution, but it is uncertain if this translates to decreased marathon performance. Purpose: The Purposes of this study were to 1) describe ambient air pollutant concentrations present during major US marathons, 2) quantify performance decrements associated with air pollutants, and 3) examine potential sex difference in performance related to air pollutants. Methods: Marathon race results, weather data, and air pollutant concentrations were obtained for seven marathons for 8-28 yr. The top three male and female finishing times were compared with the course record and contrasted with air pollutant levels and wet bulb globe temperature (WBGT). A WBGT-adjusted performance decrement was calculated, and regression analysis was used to quantify performance decrements associated with pollutants. Results: The air pollutant concentrations of carbon monoxide, ozone, particulate matter smaller than 10 microm (PM(10)), PM(2.5), nitrogen dioxide, and sulfur dioxide ranged from 0 to 5.9 ppm, from 0 to 0.07 ppm, from 4.5 to 41.0 microg x m(-3), from 2.8 to 42.0 microg x m(-3), from 0 to 0.06 ppm, and from 0 to 0.05 ppm, respectively. After adjusting for WBGT-associated performance decrements, only PM(10) was associated with decrements in performance of women. For every 10-microg x m(-3) increase in PM(10), performance can be expected to decrease by 1.4%. Conclusions: The concentrations of air pollution present during marathons rarely exceed health-based national standards and levels known to affect lung function in laboratory situations. Regardless, PM(10) was significantly correlated with performance of women marathon runners.

Training volume and personal best time in marathon, not anthropometric parameters, are associated with performance in male 100-km ultrarunners.

Knechtle B, Wirth A, Knechtle P, Rosemann T.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):604-9. Gesundheitszentrum St. Gallen, St. Gallen, Switzerland.

We investigated the relation between selected anthropometric and training variables and the personal best time in a marathon with total race time in 66 Caucasian male nonprofessional ultrarunners in a 100-km run. In the multiple linear regression analysis, the average weekly training volume in kilometers (r2 = 0.224, p < 0.01) and the personal best time in a marathon (r2 = 0.334, p 0.05). We conclude that high training volume and a fast time in a marathon were more important for a fast race time in male 100-km runners than any of the determined anthropometric variables.

Static stretching does not impair performance in active middle-aged adults.

Handrakis JP, Southard VN, Abreu JM, Aloisa M, Doyen MR, Echevarria LM, Hwang H, Samuels C, Venegas SA, Douris PC.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):825-30. NYIT-School of Health Professions, Behavioral and Life Sciences, Old Westbury, New York, USA.

Recent investigations with young, healthy adult subjects suggest that static stretching before activity decreases performance and should, therefore, be avoided. The Purpose of this study was to assess the effects of an acute static stretching protocol on balance and jump/hop performance in active middle-aged adults. Ten subjects (6 men and 4 women aged 40-60 yr) from a martial arts school volunteered to take part in this Research study. This was a repeated measures design. Subjects who stretched for 10 minutes using a 30-second hold during 1 session sat quietly for 10 minutes during the alternate session. Sessions were randomly assigned. The following dependent variables were compared: Dynamic Stability Index (DSI) for single-leg dynamic balance (smaller DSI = improved balance); distances for broad jump, single hop, triple hop, and crossover hop; elapsed time for a 6-m timed hop. Group means for balance were significantly different between the stretch and no-stretch conditions (3.5 +/- 0.7 vs. 4.3 +/- 1.4 DSI, respectively; p < 0.05). No significant differences were found between the group means of the stretch and no-stretch conditions for the dependent measures of broad jump, single hop, triple hop, crossover hop, and 6-m timed hop performance. Ten minutes of acute static stretching enhances dynamic balance and does not affect jump/hop performance in active middle-aged adults. Static stretching should be included before competition and before exercise in fitness programs of active middle-aged adults.

Reliability and factorial validity of agility tests for soccer players.

Sporis G, Jukic I, Milanovic L, Vucetic V.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):679-86 . Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia.

The Purpose of this study was to evaluate the reliability and factorial validity of agility tests used in soccer. One hundred fifty (n = 150), elite, male, junior soccer players, members of the First Junior League Team, volunteered to participate in the study. The slalom test (ST) sprint 4 x 5 m (S4 x 5) and sprint 9-3-6-3-6-9 m with 180 degree turns (S180 degrees) tests had a greater reliability coefficient (alpha = 0.992, 0.979, and 0.976), whereas the within-subject variation ranged between 2.9 and 5.6%. The mentioned 6 agility tests resulted in the extraction of 2 significant components. The S4 x 5 test had the lowest correlation coefficient with the first component (r = 0.38), whereas the correlation coefficients of the other 5 agility tests were higher than 0.63. The T-test (TT) showed statistically significant differences between the defenders and midfielders (p < 0.05) and between the defenders and attackers (p < 0.05). Statistical significant differences were determined between the attackers and defenders in the sprint 9-3-6-3-9 m with backward and forward running (SBF) and p < 0.05. It can be concluded that of the 6 agility tests used in this study, the SBF, TT, and S180 degrees are the most reliable and valid tests for estimating the agility of soccer players. According to the results of the study, the TT proved to be the most appropriate for estimating the agility of defenders, the SBF, and S180 degrees for estimating the agility of midfielders, whereas the S4 x 5 test can be used for estimating the agility of attackers.

Effect of preseason concurrent muscular Strength and high-intensity interval training in professional soccer players.

Wong PL, Chaouachi A, Chamari K, Dellal A, Wisloff U.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):653-60 . Department of Physical Education, Hong Kong Baptist University, Hong Kong.

This study examined the effect of concurrent muscular Strength and high-intensity running interval training on professional soccer players' explosive performances and aerobic endurance. Thirty-nine players participated in the study, where both the experimental group (EG, n = 20) and control group (CG, n = 19) participated in 8 weeks of regular soccer training, with the EG receiving additional muscular Strength and high-intensity interval training twice per week throughout. Muscular Strength training consisted of 4 sets of 6RM (repetition maximum) of high-pull, jump squat, bench press, back half squat, and chin-up exercises. The high-intensity interval training consisted of 16 intervals each of 15-second sprints at 120% of individual maximal aerobic speed interspersed with 15 seconds of rest. EG significantly increased (p < or = 0.05) 1RM back half squat and bench press but showed no changes in body mass. Within-subject improvement was significantly higher (p < or = 0.01) in the EG compared with the CG for vertical jump height, 10-m and 30-m sprint times, distances covered in the Yo-Yo Intermittent Recovery Test and maximal aerobic speed test, and maximal aerobic speed. High-intensity interval running can be concurrently performed with high load muscular Strength training to enhance soccer players' explosive performances and aerobic endurance.

Effects of 12-week on-field combined Strength and power training on physical performance among U-14 young soccer players.

Wong PL, Chamari K, Wisløff U.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):644-52. Department of Physical Education, Hong Kong Baptist University, Hong Kong.

This study examined the effects of on-field combined Strength and power training (CSPT) on physical performance among U-14 young soccer players. Players were assigned to experimental (EG, n = 28) and control groups (CG, n = 23). Both groups underwent preseason soccer training for 12 weeks. EG performed CSPT twice a week, which consisted of Strength and power exercises that trained the major muscles of the core, upper, and lower body. CSPT significantly (p < 0.05) improved vertical jump height, ball-shooting speed, 10 m and 30 m sprint times, Yo-Yo intermittent endurance run (YYIER), and reduced submaximal running cost (RC). CSPT had moderate effect on vertical jump, ball-shooting, 30 m sprint, and YYIER, small effect on 10 m sprint, RC, and maximal oxygen uptake. YYIER had significant (p < 0.05) correlations with 10 m (r = -0.47) and 30 m (r = -0.43) sprint times, ball-shooting speed (r = 0.51), and vertical jump (r = 0.34). The CSPT can be performed together with soccer training with no concomitant interference on aerobic capacity and with improved explosive performances. In addition, it is suggested that CSPT be performed during the preseason period rather than in-season to avoid insufficient recovery/rest or overtraining.

Effects of low- and high-volume stretching on bench press performance in collegiate football players.

Molacek ZD, Conley DS, Evetovich TK, Hinnerichs KR.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):711-6. Department of Health, Human Performance and Sport, Human Performance Laboratory, Wayne State College, Wayne, Nebraska, USA.

The Purpose of this study was to determine the effects of acute low- and high-volume static and proprioceptive neuromuscular facilitation (PNF) stretching on 1-repetition maximum (1RM) bench press. Fifteen healthy male National Collegiate Athletic Association Division II football players (age: 19.9 +/- 1.1 years; weight: 98.89 +/- 13.39 kg; height: 184.2 +/- 5.7 cm; body composition: 14.6 +/- 7.4%; and 1RM bench press: 129.7 +/- 3.3 kg) volunteered to participate in the study. Subjects completed 5 different stretching protocols integrated with a 1RM dynamic warm-up routine followed by 1RM testing in randomly assigned order. The protocols included (a) nonstretching (NS), (b) low-volume PNF stretching (LVPNFS), (c) high-volume PNF stretching (HVPNFS), (d) low-volume static stretching (LVSS), and (d) high-volume static stretching (HVSS). Two and 5 sets of stretching were completed for the low- and high-volume protocols, respectively. The stretching protocols targeted triceps and chest/shoulder muscle groups using 2 separate exercises. There were no significant differences in 1RM bench press performance (p > 0.05) among any of the stretching protocols NS (129.7 +/- 3.3 kg), LVPNFS (128.9 +/- 3.8 kg), HVPNFS (128.3 +/- 3.7 kg), LVSS (129.7 +/- 3.7 kg), and HVSS (128.2 +/- 3.7 kg). We conclude that low- and high-volume PNF and static stretching have no significant acute effect on 1RM bench press in resistance-trained collegiate football players. This suggests that resistance-trained athletes can include either (a) a dynamic warm-up with no stretching or (b) a dynamic warm-up in concert with low- or high-volume static or PNF flexibility exercises before maximal upper body isotonic resistance-training lifts, if adequate rest is allowed before performance.

Effect of squatting on sprinting performance and repeated exposure to complex training in male rugby players.

Comyns TM, Harrison AJ, Hennessy LK.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201003 24(3):610-8. Strength and Conditioning Department, Irish Rugby Football Union, Dublin 4, Ireland.

This study was undertaken to examine the effect of a heavy weight training exercise on sprinting performance and on the effect of repeated exposure to a complex training protocol. Eleven male rugby union players (age 20.9 +/- 3.1 years) participated in the study, which involved 5 separate testing sessions. Back squat 3 repetition maximum (3RM) was established in session 1. Sessions 2-5 were identical and involved the subjects completing a 30-m sprint before and after a 3RM back squat protocol. Four minutes of rest was given between the back squatting and the posttest 30-m sprint. All sprint trials were measured with a laser measurement device (LAVEG, Jenoptik, Jena, Germany). Sprint time and instantaneous, average, and maximum velocity were the dependent variables. The criterion for significance was set at an alpha level of p > or = 0.05. No significant improvement was evident for any of the testing sessions (p > or = 0.05). In session 1, there was a significant increase in 30-m time and a significant reduction in average 30-m velocity and maximum velocity (p < 0.05). The expected benefits in sprinting may not have been realized because of intra and intersubject variations in sprint technique. The session x phase interaction revealed a significant improvement in the pre to posttest changes in instantaneous velocity at 20 m (p = 0.035) and 30 m (p = 0.036) from session 1 to session 4. This indicates that the rugby players may be able to learn to apply the potentiation effects of complex training. From a practical perspective, players may need repeated exposure to this training modality to gain benefit from it, and this should be reflected in program planning.

Is hypoxia training good for muscles and exercise performance?

Vogt M, Hoppeler H.: Progress in Cardiovascular Diseases, 2010 May-Jun 52(6):525-33 Department of Anatomy, University of Bern, CH-3012 Bern, Switzerland.

Altitude training has become very popular among athletes as a means to further increase exercise performance at sea level or to acclimatize to competition at altitude. Several approaches have evolved during the last few decades, with "live high-train low" and "live low-train high" being the most popular. This review focuses on functional, muscular, and practical aspects derived from extensive Research on the "live low-train high" approach. According to this, subjects train in hypoxia but remain under normoxia for the rest of the time. It has been reasoned that exercising in hypoxia could increase the training stimulus. Hypoxia training studies published in the past have varied considerably in altitude (2300-5700 m) and training duration (10 days to 8 weeks) and the fitness of the subjects. The evidence from muscle structural, biochemical, and molecular findings point to a specific role of hypoxia in endurance training. However, based on the available performance capacity data such as maximal oxygen uptake (Vo(2)max) and (maximal) power output, hypoxia as a supplement to training is not consistently found to be advantageous for performance at sea level. Stronger evidence exists for benefits of hypoxic training on performance at altitude. "Live low-train high" may thus be considered when altitude acclimatization is not an option. In addition, the complex pattern of gene expression adaptations induced by supplemental training in hypoxia, but not normoxia, suggest that muscle tissue specifically responds to hypoxia. Whether and to what degree these gene expression changes translate into significant changes in protein concentrations that are ultimately responsible for observable structural or functional phenotypes remains open. It is conceivable that the global functional markers such as Vo(2)max and (maximal) power output are too coarse to detect more subtle changes that might still be functionally relevant, at least to high-level athletes.

Variation in human performance in the hypoxic mountain environment.

Martin DS, Levett DZ, Grocott MP, Montgomery HE.: Experimental Physiology, 201003 95(3):463-70. UCL Institute for Human Health and Performance, 2nd Floor, Charterhouse Building, UCL Archway Campus, Highgate Hill, Archway, London N19 5LW, UK.

Ascent to altitude is associated with a fall in barometric pressure, and with it a decline in the partial pressure of atmospheric (and thus alveolar) oxygen. As a result, a variety of adaptive physiological processes are engaged to mitigate the fall in tissue convective oxygen delivery which might otherwise occur. The magnitude and nature of such changes is also modified with time, a process known as acclimatization. However, other phenomena are at work; the ability to perform physical work at altitude falls in a manner which is not wholly related to changes in arterial oxygen content. Indeed, alterations in local skeletal muscle blood flow and metabolism may play an axial role. Thus, for those who are not native to high altitude, the ability to compete at altitude is likely to be impaired. The magnitude of such impairment in performance, however, differs greatly between individuals, and it seems that genetic variation underpins much of this difference. The identification of the relevant genetic elements is in its infancy in humans, but ongoing work is likely to help us gain an increasing understanding of how humans adapt to altitude and to develop mitigating interventions.

Watching a previous victory produces an increase in testosterone among elite hockey players.

Carré JM, Putnam SK.: Psychoneuroendocrinology, 201004 35(3):475-9. Department of Psychology, Brock University, St Catharines, Ontario, Canada.

Previous Research indicates that testosterone concentrations are highly responsive to human competitive interactions and that winners have elevated testosterone concentrations relative to losers. Also, there is some evidence that simply observing others compete can have a similar effect on the endocrine system. Here, in two studies, we examined the extent to which elite male hockey players would demonstrate an increase in testosterone concentrations after watching themselves engaged in a previous successful competitive interaction. Results indicated that watching a previous victory produced a significant increase in testosterone concentrations (42-44% increase), whereas watching a previous defeat or a neutral video did not produce a significant change in testosterone (17% and 6%, respectively). Given that natural fluctuations in testosterone have been shown to influence future competitive and aggressive behaviours, the current studies may have important practical implications for individuals involved in competitive sports.

Young tennis players and balance performance.

Malliou VJ, Beneka AG, Gioftsidou AF, Malliou PK, Kallistratos E, Pafis GK, Katsikas CA, Douvis S

Journal of Strength and Conditioning Research / National Strength & Conditioning Association

201002 24(2):389-93. Department of Physical Education & Sports Science, National & Kapodistrian University of Athens, Athens, Greece.

The Purpose of the present study was to investigate the effect of a tennis training session on the balance performance of young tennis players. The study was conducted on 36 elite tennis players (age 14 +/- 2 years; body mass 55 +/- 6 kg; body height 165 +/- 6 cm; mean +/- SD) participating in the national young tennis championship. Balance performance was assessed before and immediately after a tennis training session (pre-training and post-training, respectively). The balance assessment was performed with 2 different balance boards and the Biodex Stability System. In addition, dynamometric measurements of peak isokinetic moment in the knee flexors and extensors were performed pre and post tennis training session, to quantify the degree of muscle fatigue induced by the tennis training session. One-way analysis of variance with repeated measures was used to test for differences in balance performance and in isokinetic performance between pre and post tennis training session. The data analysis revealed no significant differences (p > 0.05) in balance performance, whereas there were significant differences in knee joint moment production between pre and post tennis training measures. Although the tennis training session of the present study had no significant effect (p > 0.05) on any of the balance performance indicators examined, there was a decline in balance performance, which suggests that different level of fatigue for an extended period (games) will have greater effect on balance performance. It is suggested that a tennis-specific balance exercise program should be included in the tennis training session.

Upper-body Strength and power changes during a football season.

Hrysomallis C.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201002 24(2):557-9. Centre for Ageing, Rehabilitation, Exercise and Sport, Victoria University, Melbourne, Australia.

There are different football codes played around the world, and most of them involve contact and collision during competition. Upper-body Strength and power are important for success in American football, rugby league, rugby union, and Australian football. The goal of the preseason Conditioning program is usually to maximize muscular fitness before the competitive season. The in-season program is usually intended to maintain the preseason gains, but it is unclear as to whether the preseason levels of upper-body Strength and power can be maintained or even increased during the in-season. The aims of this review were to investigate and identify any general trends in the training programs and results of football studies that have monitored levels of upper-body Strength and power preseason, in-season, or postseason. Six studies were identified: 4 involved American college football and the other 2 involved rugby codes and included professional athletes. For most studies, resistance training was conducted 4 times per week preseason and reduced to 2 times per week in-season. The bench press exercise was used as the measure of upper-body strength, and only one of the rugby studies measured upper-body power and used bench press throws. It was found that upper-body Strength or power could be maintained or even increased past the mid-season point, but this may be dependent on age, football code, and level of play. At the end of the season, decreases were starting to be reported but only for 2 studies. Surprisingly, an increase in Strength was reported postseason for college rugby league players. From the available information, it seems that an in-season periodized program that includes high-intensity resistance training may optimize Strength and power ability during the in-season, but more Research is required that compares the effectiveness of Conditioning programs with varying combinations of training variables.

Early-phase resistance training Strength gains in novice lifters are enhanced by doing static stretching.

Kokkonen J, Nelson AG, Tarawhiti T, Buckingham P, Winchester JB.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201002 24(2):502-6. Exercise and Sport Science Department, Brigham Young University-Hawaii, Laie, Hawaii, USA.

This study investigated differences in lower-body Strength improvements when using standard progressive resistance training (WT) vs. the same progressive resistance training combined with static stretching exercises (WT + ST). Thirty-two college students (16 women and 16 men) were pair matched according to sex and knee extension 1 repetition maximum (1RM). One person from each pair was randomly assigned to WT and the other to WT + ST. WT did 3 sets of 6 repetitions of knee extension, knee flexion, and leg press 3 days per week for 8 weeks with weekly increases in the weight lifted. The WT + ST group performed the same lifting program as the WT group along with static stretching exercises designed to stretch the hip, thigh, and calf muscle groups. Stretching exercise sessions were done twice a week for 30 minutes during the 8-week period. WT significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 12, 14, and 9%, respectively. WT + ST, on the other hand, significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 16, 27, and 31, respectively. In addition, the WT + ST group had significantly greater knee extension and leg press gains (p < 0.05) than the WT group. Based on results of this study, it is recommended that to maximize Strength gains in the early phase of training, novice lifters should include static stretching exercises to their resistance training programs.

Game-induced fatigue patterns in elite female soccer.

Krustrup P, Zebis M, Jensen JM, Mohr M.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201002 24(2):437-41. Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark.

The Purpose was to examine the fatigue pattern of elite female soccer players after competitive games. Soccer players (n = 23) from the Danish women Premier League performed a countermovement vertical jump test, a repeated 30-m sprint test, and the Yo-Yo intermittent endurance level 2 (Yo-Yo IE2) test at rested state and after a competitive game. Average heart rate during the game was 86 +/- 1% of maximal heart rate with no differences between halves. Blood lactate was 5.1 +/- 0.5 mmol.L after the first half, which was higher (p < 0.05) than after the second half (2.7 +/- 0.4 mmol.L). Yo-Yo IE2 performance was 484 +/- 50 m after the game, which was 62% lower (p < 0.05) than at rested state (1,265 +/- 133 m). Average sprinting time of three 30-m sprints was 5.06 +/- 0.06 seconds after the game, which was 4% slower (p < 0.05) than at rest (4.86 +/- 0.06 seconds). No game-induced effect was observed on vertical jump performance. Significant inverse correlations were observed between Yo-Yo IE2 test performance and fatigue index during the repeated sprint test both at rest (r = -0.76, p < 0.05) and after the game (r = -0.66, p < 0.05). The study demonstrates that the type of fatigue that occurs after a female soccer game does cause marked impairment in intense intermittent exercise and repeated sprint performance but does not affect vertical jump performance. These findings support the notion that decrements in distance covered by sprinting and high-speed running toward the end of elite female games are caused by fatigue.

Effects of simulated and real altitude exposure in elite swimmers.

Robertson EY, Aughey RJ, Anson JM, Hopkins WG, Pyne DB.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 201002 24(2):487-93. Department of Physiology, Australian Institute of Sport, Canberra, Australia.

The effect of repeated exposures to natural and simulated moderate altitude on Physiology and competitive performance of elite athletes warrants further investigation. This study quantified changes in hemoglobin mass, performance tests, and competitive performance of elite swimmers undertaking a coach-prescribed program of natural and simulated altitude training. Nine swimmers (age 21.1 +/- 1.4 years, mean +/- SD) completed up to four 2-week blocks of combined living and training at moderate natural altitude (1,350 m) and simulated live high-train low (2,600-600 m) altitude exposure between 2 National Championships. Changes in hemoglobin mass (Hbmass), 4-mM lactate threshold velocity, and 2,000 m time trial were measured. Competition performance of these swimmers was compared with that of 9 similarly trained swimmers (21.1 +/- 4.1 years) who undertook no altitude training. Each 2-week altitude block on average produced the following improvements: Hbmass, 0.9% (90% confidence limits, +/-0.8%); 4-mM lactate threshold velocity, 0.9% (+/-0.8%); and 2,000 m time trial performance, 1.2% (+/-1.6%). The increases in Hbmass had a moderate correlation with time trial performance (r = 0.47; +/-0.41) but an unclear correlation with lactate threshold velocity (r = -0.23; +/-0.48). The altitude group did not swim faster at National Championships compared with swimmers who did not receive any altitude exposure, the difference between the groups was not substantial (-0.5%; +/-1.0%). A coach-prescribed program of repeated altitude training and exposure elicited modest changes in Physiology but did not substantially improve competition performance of elite swimmers. Sports should investigate the efficacy of their altitude training program to justify the investment.

Effect of in- versus out-of-water recovery on repeated swimming sprint performance.

Buchheit M, Al Haddad H, Chivot A, Leprêtre PM, Ahmaidi S, Laursen PB

European Journal of Applied Physiology, 201001 108(2):321-7 Research Laboratory, EA 3300, Laboratory of Exercise Physiology and Rehabilitation, Faculty of Sport Sciences, University of Picardie, Jules Verne, 80025, Amiens, France.

The aim of this study was to compare the effect of passive in- (IN) versus out-of-(OUT) water recovery on performance during repeated maximal sprint swimming. Nine well-trained male swimmers (21 +/- 3.5 years) performed six repeated maximal 50-m sprints (RS), departing every 2 min, interspersed with either IN or OUT recovery. Best (RS(b)) and mean (RS(m)) RS times, percentage speed decrement (%Dec) and between-sprint heart rate recovery (HRR(80s)) were calculated for both conditions. Blood lactate was measured after the third ([La](b) S3) and sixth sprints (post [La](b)). Rating of perceived recovery level (REC) and exertion (RPE) were collected before and after each sprint. Repeated sprint performance was significantly lower in the OUT condition (i.e., for RS(m), P = 0.02, +1.3%, 90% CI -0.7, 3.2%). OUT was also associated with poorer HRR(80s) (P < 0.001, -23%, 90% CI -34, -10%) and higher [La](b) S3 (P 0.43). To conclude, present results confirm the beneficial effect of the IN condition on repeated swim sprint performance, but also suggest that the OUT recovery modality could be an effective training practice for eliciting a low intramuscular energy status.

Acute alcohol consumption aggravates the decline in muscle performance following strenuous eccentric exercise.

Barnes MJ, Mündel T, Stannard SR.: Journal of Science and Medicine in sport / Sports Medicine Australia, 201001 13(1):189-93. Institute of Food, Nutrition, and Human Health, Massey University, Palmerston North, New Zealand.

This study investigated the effects of acute moderate alcohol intake on muscular performance during recovery from eccentric exercise-induced muscle damage. Eleven healthy males performed 300 maximal eccentric contractions of the quadriceps muscles of one leg on an isokinetic dynamometer. They then consumed a beverage containing 1g/kg bodyweight ethanol (as vodka and orange juice) (ALC). On another occasion they performed an equivalent bout of eccentric exercise on the contralateral leg after which they consumed an isocaloric quantity of orange juice (OJ). Measurement of maximal isokinetic (concentric and eccentric) and isometric torque produced across the knee, plasma creatine kinase (CK) concentrations and muscle soreness were made before and at 36 and 60h following each exercise bout. All measures of muscle performance were significantly reduced at 36 and 60h post-exercise compared to pre-exercise measures (all p0.05). These results indicate that consumption of even moderate amounts of alcohol following eccentric-based exercise magnifies the normally observed losses in dynamic and static strength. Therefore, to minimise exercise related losses in muscle function and expedite recovery, participants in sports involving eccentric muscle work should avoid alcohol-containing beverages in the post-event period.

Neuromuscular fatigue induced by an isotonic heavy-resistance loading protocol in knee extensors.

Walker S, Peltonen J, Ahtiainen JP, Avela J, Hakkinen K.: Journal of Sports Sciences, 200910 27(12):1271-9. Department of Biology of Physical Activity, University of Jyvaskyla, Jyvaskyla, Finland.

The main aim of this study was to assess neuromuscular fatigue during a typical high-load, low-repetition loading protocol. Muscle stimulations were used to assess maximum voluntary contraction, resting single- and double-pulse twitch characteristics, and superimposed double-pulse twitch force (used to calculate voluntary activation) before and after an acute knee extension loading protocol. In our participants, who had previous resistance training experience, the mean voluntary activation level was 96.2% in an unfatigued state. Maximum voluntary contraction (-11.8%), resting double-pulse twitch force (-10.6%), and voluntary activation (-2.1%) were markedly decreased as a consequence of loading (P < 0.05). In addition, although potentiated twitch characteristics were observed during the loading protocol, this was short-lived, as fatigue surpassed the potentiation mechanisms. Our results show that both central and peripheral mechanisms contributed to neuromuscular fatigue during the present loading protocol.

Modificado em 17 de Junho de 2010

Usefulness of the jump-and-reach test in assessment of vertical jump performance.

Menzel HJ, Chagas MH, Szmuchrowski LA, Araujo SR, Campos CE, Giannetti MR.: Perceptual and Motor Skills, 2010, 110(1):150-8. School of Physical Education, Physiotherapy and Occupational Therapy Federal University of Minas Gerais, Belo Horizonte, Brazil.

The objective was to estimate the reliability and criterion-related validity of the Jump-and-Reach Test for the assessment of squat, countermovement, and drop jump performance of 32 male Brazilian professional volleyball players. Performance of squat, countermovement, and drop jumps with different dropping heights was assessed on the Jump-and-Reach Test and the measurement of flight time, then compared across different jump trials. The very high reliability coefficients of both assessment Methods and the lower correlation coefficients between scores on the assessments indicate a very high consistency of each method but only moderate covariation, which means that they measure partly different items. As a consequence, the Jump-and-Reach Test has good ecological validity in situations when reaching height during the flight phase is critical for performance (e.g., basketball and volleyball) but only limited accuracy for the assessment of vertical impulse production with different jump techniques and conditions.

Respiratory muscle endurance training: effect on normoxic and hypoxic exercise performance.

Keramidas ME, Debevec T, Amon M, Kounalakis SN, Simunic B, Mekjavic IB.: European Journal of Applied Physiology, 2010, 108(4):759-69. Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.

The aim of this study was to investigate the effect of respiratory muscle endurance training on endurance exercise performance in normoxic and hypoxic conditions. Eighteen healthy males were stratified for age and aerobic capacity; and randomly assigned either to the respiratory muscle endurance training (RMT = 9) or to the control training group (CON = 9). Both groups trained on a cycle-ergometer 1 h day(-1), 5 days per week for a period of 4 weeks at an intensity corresponding to 50% of peak power output. Additionally, the RMT group performed a 30-min specific endurance training of respiratory muscles (isocapnic hyperpnea) prior to the cycle ergometry. Pre, Mid, Post and 10 days after the end of training period, subjects conducted pulmonary function tests (PFTs), maximal aerobic tests in normoxia (VO(2max)NOR), and in hypoxia (VO(2max)HYPO; F(I)O(2) = 0.12); and constant-load tests at 80% of VO(2max)NOR in normoxia (CLT(NOR)), and in hypoxia (CLTHYPO). Both groups enhanced VO(2max)NOR (CON: +13.5%; RMT: +13.4%), but only the RMT group improved VO(2max)HYPO Post training (CON: -6.5%; RMT: +14.2%). Post training, the CON group increased peak power output, whereas the RMT group had higher values of maximum ventilation. Both groups increased CLT(NOR) duration (CON: +79.9%; RMT: +116.6%), but only the RMT group maintained a significantly higher CLT(NOR) 10 days after training (CON: +56.7%; RMT: +91.3%). CLT(HYPO) remained unchanged in both groups. Therefore, the respiratory muscle endurance training combined with cycle ergometer training enhanced aerobic capacity in hypoxia above the control values, but did not in normoxia. Moreover, no additional effect was obtained during constant-load exercise.

Respiratory muscle training reduces the work of breathing at depth.

Ray AD, Pendergast DR, Lundgren CE.: European Journal of Applied Physiology, 2010, 108(4):811-20. Department of Rehabilitation Science, Center for Research and Education in Special Environments, School of Public Health and Health Professions, State University of New York at Buffalo, Kimball Tower, Rm. 515, 3435 Main Street, Buffalo, NY 14214, USA.

Resistance respiratory muscle training (RRMT) increases respiratory muscle and swimming performance at depths down to 17 msw. It is unknown if RRMT improves swimming performance at greater depths and if the improvements are associated with a reduced work of breathing (WOB), altered respiratory mechanics and/or improved respiratory muscle performance. Eight male subjects (30.3 +/- 6.0 years) were tested swimming underwater in a hyperbaric chamber at 37 m of depth against a pre-determined load (70% VO(2)) until exhausted. End expiratory lung volume (EELV) was determined by subtracting inspiratory capacity from total lung capacity throughout the swims. The mechanical WOB on the lung was calculated as the integrated product of the transpulmonary pressure and ventilatory flow. Maximal expiratory (P EMAX) and inspiratory pressures (P IMAX) were measured pre- and post-RRMT. RRMT was performed every 30 s against spring loaded inspiratory and expiratory valves 30 min/day, 5 days/week, for 4 weeks. RRMT increased P (IMAX) and P (EMAX) by 40% (110 +/- 11 cmH2O (SD) vs. 155 +/- 22, p < 0.001) and 30% (148 +/- 33 cmH2O vs. 192 +/- 49, p < 0.001), respectively, respiratory endurance by 75% (19.7 +/- 15.4 min vs. 34.4 +/- 27.3, p = 0.010), and swimming endurance by 87% (26.4 +/- 9.7 min vs. 49.4 +/- 21.6, p = 0.004). The longer swimming time was associated with reduced V(E) and V(A) (p < 0.001), f(b) (p < 0.001), V(CO(2)) (p < 0.001) and WOB (p < 0.001). There were no changes in EELV post-RRMT. These results suggest the improved exercise performance post-RRMT was associated with stronger respiratory muscles, a decreased f b, and a reduced WOB.

Physiological factors to predict on traditional rowing performance.

Izquierdo-Gabarren M, Expósito RG, de Villarreal ES, Izquierdo M.: European Journal of Applied Physiology, 2010, 108(1):83-92. Research Center of Rowing Club Orio, Orio, Spain.

The Purpose of this study was to determine the best prediction factors of traditional rowing performance in traditional elite (ER) and amateur (AR) rowers. Average power during the 20-min all-out test (W(20 min)), average power output which elicited a blood lactate concentration of 4 mmol l(-1) (W(4 mmol l(-1))), power output in 10 maximal strokes (W(10 strokes)), maximal strength and muscle power output during a bench pull (BP) and anthropometric values were all measured for 46 trained male rowers aged 21-30 with 8-15 years of rowing training experience. The ER group showed greater body mass (5%, p < 0.05), greater fat free body mass (5%, p < 0.05), greater 1RM(BP) (13%, p < 0.001), longer training experience (43%, p < 0.001), and a shorter time in the 2,000 m test (4%, p < 0.05) than the AR group. The ER group showed higher power output values in W(10 strokes) (9%, p < 0.01), W(20 min) (15.4%, p < 0.01) and (W(4 mmol l(-1))) (17.8%, p < 0.01) compared with the AR group. Significant relationships were observed between (W(4 mmol l(-1))) and W(20 min) (r = 0.65 and 0.80; p < 0.01 in ER and AR, respectively). The indices for rowing performance suggested that W(20 min), (W(4 mmol l(-1))), W(10 strokes) and 1RM(BP) were the most important predictors of traditional rowing performance in elite and amateur rowers.

Reproducibility of performance changes to simulated live high/train low altitude.

Robertson EY, Saunders PU, Pyne DB, Aughey RJ, Anson JM, Gore CJ.: Medicine and Science in Sports and Exercise, 2010, 42(2):394-401. Department of Physiology, Australian Institute of Sport, Canberra, Australia.

Elite athletes often undertake multiple altitude exposures within and between training years in an attempt to improve sea level performance. Purpose: To quantify the reproducibility of responses to live high/train low (LHTL) altitude exposure in the same group of athletes. Methods: Sixteen highly trained runners with maximal aerobic power (VO2max) of 73.1 +/- 4.6 and 64.4 +/- 3.2 mL x kg(-1) x min(-1) (mean +/- SD) for males and females, respectively, completed 2 x 3-wk blocks of simulated LHTL (14 h x d(-1), 3000 m) or resided near sea level (600 m) in a controlled study design. Changes in the 4.5-km time trial performance and physiological measures including VO2max, running economy and hemoglobin mass (Hb(mass)) were assessed. Results: Time trial performance showed small and variable changes after each 3-wk altitude block in both the LHTL (mean [+/-90% confidence limits]: -1.4% [+/-1.1%] and 0.7% [+/-1.3%]) and the control (0.5% [+/-1.5%] and -0.7% [+/-0.8%]) groups. The LHTL group demonstrated reproducible improvements in VO2max (2.1% [+/-2.1%] and 2.1% [+/-3.9%]) and Hb(mass) (2.8% [+/-2.1%] and 2.7% [+/-1.8%]) after each 3-wk block. Compared with those in the control group, the runners in the LHTL group were substantially faster after the first 3-wk block (LHTL - control = -1.9% [+/-1.8%]) and had substantially higher Hb(mass) after the second 3-wk block (4.2% [+/-2.1%]). There was no substantial difference in the change in mean VO2max between the groups after the first (1.2% [+/-3.3%]) or second 3-wk block (1.4% [+/-4.6%]). Conclusions: Three-week LHTL altitude exposure can induce reproducible mean improvements in VO2max and Hb(mass) in highly trained runners, but changes in time trial performance seem to be more variable. Competitive performance is dependent not only on improvements in physiological capacities that underpin performance but also on a complex interaction of many factors including fitness, fatigue, and motivation.

The effect of training volume and intensity on competitive cyclists' efficiency.

Hopker J, Coleman D, Passfield L, Wiles J.: Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquée, Nutrition et Métabolisme, 2010, 35(1):17-22. Centre for Sports Studies, University of Kent, Chatham Maritime, Chatham, Kent, ME4 4AG, UK.

The impact of different intensity training on cycling efficiency in competitive cyclists is unknown. Twenty-nine endurance-trained competitive male cyclists completed 3 laboratory visits during a 12-week training period. At each visit, their cycling efficiency and maximal oxygen uptake were determined. After the first visit, cyclists were randomly split into 2 groups (A and B). Over the first 6 weeks, between tests 1 and 2, group A was prescribed specific high-intensity training sessions, whereas group B was restricted in the amount of intensive work undertaken. After test 2 and for the second 6-week period, group B was allowed to conduct high-intensity training. Gross efficiency (GE) increased in group A (+1.6 +/- 1.4%; p 0.05). Group B cyclists increased their GE between tests 2 and 3 (+1.4 +/- 0.8%; p 0.05). Delta efficiency (DE) did not change significantly in either group across the study period. This study demonstrates that GE is increased following high-intensity training in competitive male cyclists after 12 weeks.

Effects of aerobic fitness on hypohydration-induced physiological strain and exercise impairment.

Merry TL, Ainslie PN, Cotter JD.: Acta Physiologica (Oxford, England), 2010, 198(2):179-90. School of Physical Education, University of Otago, Dunedin, New Zealand.

AIM: Hypohydration exacerbates cardiovascular and thermal strain and can impair exercise capacity in temperate and warm conditions. Yet, athletes often dehydrate in exercise, are hypervolaemic and have less cardiovascular sensitivity to acute hypervolaemia. We tested the hypothesis that trained individuals have less cardiovascular, thermoregulatory and performance affect of hypohydration during exercise. Methods: After familiarization, six trained [VO(2 peak) = 64 (SD 8) mL kg(-1) min(-1)] and six untrained [O(2 peak) = 45 (4) mL kg(-1) min(-1)] males cycled 40 min at 70%O(2 peak) while euhydrated or hypohydrated by 1.5-2.0% body mass (crossover design), before a 40-min work trial with euhydration or ad libitum drinking (in Hypohydration trial), in temperate conditions (24.3 degrees C, RH 50%, v(a) = 4.5 m s(-1)). Baseline hydration was by complete or partial rehydration from exercise+heat stress the previous evening. Results: During constant workload, heart rate and its drift were increased in Hypohydration compared with Euhydration for Untrained [drift: 33 (11) vs. 24 beats min(-1) h(-1) (10), 95% CI 5-11] but not Trained [14 (3) vs. 13 beats min(-1) h(-1) (3), CI -2 to 3; P = 0.01 vs. Untrained]. Similarly, rectal temperature drift was faster in Hypohydration for Untrained only [by 0.57 degrees C h(-1) (0.25); P = 0.03 vs. Trained], concomitant with their reduced sweat rate (P = 0.05) and its relation to plasma osmolality (P = 0.03). Performance power tended to be reduced for Untrained (-13%, CI -35 to 2) and Trained (-7%, CI: -16 to 1), without an effect of fitness (P = 0.38). Conclusion: Mild hypohydration exacerbated cardiovascular and thermoregulatory strain and tended to impair endurance performance, but aerobic fitness attenuated the physiological effects.

Modificado em 26 de Maio de 2010

Effects of a recovery swim on subsequent running performance.

Lum D, Landers G, Peeling P.: International Journal of Sports Medicine, 2010 31(1):26-30. The University of Western Australia, School of Sport Science, Exercise and Health, Crawley, Australia.

The effects of a swimming-based recovery session implemented 10 h post high intensity interval running on subsequent run performance the next day was investigated. Nine well trained triathletes performed two high intensity interval running sessions (HIIS) (8x3 min at 85-90% VO(2peak) velocity), followed 10 h later by either a swim recovery session (SRS) (20x100 m at 90% of 1 km time trial speed), or a passive recovery session (PRS). Subsequently, a time to fatigue run (TTF) was completed 24 h post-HIIS. Venous blood samples were taken pre-HIIS and pre-TTF to determine the levels of circulating C-Reactive Protein (CRP). Subjects were also asked to rate their perceived recovery prior to commencing the TTF run. The SRS resulted in a significantly longer (830+/-198 s) TTF as compared to PRS (728+/-183 s) ( P=0.005). There was also a significant percentage change from baseline in the CRP levels 24 h post-HIIS (SRS=-23%, PRS=+/-5%, P=0.007). There were no significant differences in perceived recovery between two conditions ( P=0.40) . The findings of the present study showed that a swimming-based recovery session enhanced following day exercise performance, possibly due to the hydrostatic properties of water and its associated influence on inflammation.

Influence of acetaminophen on performance during time trial cycling.

Mauger AR, Jones AM, Williams CA.: Journal of Applied Physiology (Bethesda, Md. : 1985), 2010 108(1):98-104. Dept. of Sport and Exercise Sciences, Univ. of Bedfordshire, Polhill Campus, Polhill Ave., Bedford MK419EA, United Kingdom.

To establish whether acetaminophen improves performance of self-paced exercise through the reduction of perceived pain, 13 trained male cyclists performed a self-paced 10-mile (16.1 km) cycle time trial (TT) following the ingestion of either acetaminophen (ACT) or a placebo (PLA), administered in randomized double-blind design. TT were completed in a significantly faster time (t(12) = 2.55, P < 0.05) under the ACT condition (26 min 15 s +/- 1 min 36 s vs. 26 min 45 s +/- 2 min 2 s). Power output (PO) was higher during the middle section of the TT in the ACT condition, resulting in a higher mean PO (P < 0.05) (265 +/- 12 vs. 255 +/- 15 W). Blood lactate concentration (B[La]) and heart rate (HR) were higher in the ACT condition (B[La] = 6.1 +/- 2.9 mmol/l; HR = 87 +/- 7%max) than in the PLA condition (B[La] = 5.1 +/- 2.6 mmol/l; HR = 84 +/- 9%max) (P 0.05) was observed. Using acetaminophen, participants cycled at a higher mean PO, with an increased HR and B[La], but without changes in perceived pain or exertion. Consequently, completion time was significantly faster. These findings support the notion that exercise is regulated by pain perception, and increased pain tolerance can improve exercise capacity.

Effects of age and rest interval on strength recovery.

Bottaro M, Ernesto C, Celes R, Farinatti PT, Brown LE, Oliveira RJ.: International Journal of Sports Medicine, 2010, 31(1):22-5. University of Brasília, College of Physical Education, Brasília, Brazil.

The purpose of this study was to compare the effect of two different rest intervals between sets of isokinetic knee extension exercise on peak torque (PT), and Total Work (TW) between untrained younger and older men. Seventeen young men (24.22+/-2.58 yrs) and 20 older men (66.85+/-4.02 yrs) performed 3 sets of 10 unilateral isokinetic knee extension repetitions at 60 degrees /s. The rest intervals between sets were 1 and 2 min. There was a significant decline in PT when 1 and 2 min rest intervals were used for young men, but not when a 2 min rest interval was applied for old men. There was also a significant decline in TW among the 3 sets when 1 and 2 min rest intervals were applied for young men, whereas the decline in TW in older men occurred only between the 2(nd) and 3(rd) sets. PT and TW in the 3(rd) set were significant greater following a 2 min rest interval than a 1 min rest in both young and older men. The present study indicated that non-resistance trained young men may require longer rest interval to recover full PT and TW when compared to older men.

Modificado em 23 de Maio de 2010

Effect of static and dynamic stretching on vertical jump performance in collegiate women volleyball players.

Dalrymple KJ, Davis SE, Dwyer GB, Moir GL.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 2010, 24(1):149-55. Exercise Science Department, East Stroudsburg University of Pennsylvania, East Stroudsburg, Pennsylvania, USA.

The purpose of this study was to determine the effect of stretching on peak jump height during a series of vertical jumps, specifically focusing on a) static stretching (SS), b) dynamic stretching (DS) and c) no stretching (NS) performed immediately before a series of countermovement vertical jumps (CMJ). Twelve female collegiate volleyball players (mean +/- SD; age 19.5 +/- 1.1 yr; height 1.71 +/- 0.06 m; mass 71.3 +/- 8.54 kg) volunteered for this study. Data collection lasted a total of 3 weeks, and each subject performed all 3 stretching protocols, 1 session per week, with 1 week between sessions. The order of the stretching protocols was randomized for each subject. During each testing session, all subjects performed a 5-minute light jog as a warm-up, followed by 8 minutes of 1 of the stretching protocols. One minute after the completion of each protocol, 5 maximal CMJ were performed on a force platform, with each jump separated by 1 minute of passive recovery. Jump heights were calculated by integrating the vertical force trace. There were no significant differences between the SS, DS, and NS conditions for any of the jumps (p > 0.05). Despite the lack of significant effects for the group, there were notable individual responses to each of the warm-up conditions. Practitioners should be aware of the individual responses of their athletes to different types of warm-up protocols before athletic performance and the possible impact of prescribing or eliminating certain exercises.

Shuttle swim test for water polo players: validity and reliability.

Melchiorri G, Manzi V, Padua E, Sardella F, Bonifazi M.: The Journal of Sports Medicine and Physical Fitness, 2009 49(3):327-30. Motor Science Department, Tor Vergata University, Rome, Italy.

Aim: The purpose of this study, carried out on elite water polo players, was to examine: 1) the relationship between the shuttle swim test (SST) and the performance during official water polo games, and 2) the SST reliability. Methods: Sixteen male players of the Italian National Water Polo Team (age: 27.9 + or - 2.1 years, body mass: 88.5 + or - 10.3 kg, height: 186.6 + or - 6.9 cm) performed the SST, consisting of two sets of seven repetitions from 40 to 10 m (total of 120 m for each set) at a maximal intensity with 90 s of rest between sets. During the SST, average swimming speed, blood lactate concentration and heart rate were recorded. Direct validity of the SST was evaluated by comparing the average swimming speed with the total distance covered (TD) and the distance covered at high intensity swimming (above 1.8 m x s(-1), HIS) during three official water polo games. SST reliability was assessed by testing the same athletes one week apart. Results: Average swimming speed during the SST was significantly correlated with TD (r=0.67, P<0.01) and HIS (r=0.74, P<0.004). The mean average speed during SST showed high reliability (TE=0.4%; CI 95%: 0.2% to 1.0% ). The T1 vs. T2 difference in mean average speed was not significant. Conclusions: Present findings demonstrate the validity and reliability of the SST for evaluation of the swimming fitness of water polo players.

Modificado em 04 de Abril de 2010

Influence of work-interval intensity and duration on time spent at a high percentage of VO₂max during intermittent supramaximal exercise.

Wakefield BR, Glaister M.:

Journal of Strength and Conditioning research / National Strength & Conditioning Association, 23(9):2548-54, 2009. School of Human Sciences, St. Mary's University College, Twickenham, United Kingdom.

The purpose of this study was to examine the effect of work-interval duration (WID) and intensity on the time spent at, or above, 95% VO2max (T95 VO₂max) during intermittent bouts of supramaximal exercise. Over a 5-week period, 7 physically active men with a mean (+/-SD) age, height, body mass, and VO₂max of 22 +/- 5 years, 181.5 +/- 5.6 cm, 86.4 +/- 11.4 kg, and 51.5 +/- 1.5 ml.kg-1.min-1, respectively, attended 7 testing sessions. After completing a submaximal incremental test on a treadmill to identify individual oxygen uptake/running velocity relationships, subjects completed a maximal incremental test to exhaustion to VO2max and subsequently (from the aforementioned relationship) the minimum velocity required to elicit VO2max (vVO₂max). In a random order, subjects then carried out 3 intermittent runs to exhaustion at both 105% and 115% vVO₂max. Each test used a different WID (20 s, 25 s, or 30 s) interspersed with 20-second passive recovery periods. Results revealed no significant difference in T95 vVO₂max for intermittent runs at 105% versus 115% vVO2max (p = 0.142). There was, however, a significant effect (p < 0.001) of WID on T95 VO₂max, with WIDs of 30 seconds enabling more time relative to WIDs of 20 seconds (p = 0.018) and 25 seconds (p = 0.009). Moreover, there was an interaction between intensity and duration such that the effect of WID was magnified at the lower exercise intensity (p = 0.046). In conclusion, despite a number of limitations, the results of this investigation suggest that exercise intensities of approximately 105% vVO₂max combined with WIDs greater than 25 seconds provide the best way of optimizing T95 VO₂max when using fixed 20-second stationary rest periods.

Effects of manual resistance training on fitness in adolescents.

Dorgo S, King GA, Candelaria NG, Bader JO, Brickey GD, Adams CE.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 23(8):2287-94, 2009. Department of Kinesiology, The University of Texas at El Paso, El Paso, Texas, USA. Este endereço de e-mail está protegido de spam bots, pelo que necessita do Javascript activado para o visualizar Manual resistance training (MRT), an alternative to traditional resistance training, requires minimal equipment and may be effective when applied in school-based physical education (PE) classes. The purpose of this study was to document the physical changes in adolescents (n = 222) using MRT in school-based PE settings. Six fitness tests from the Fitnessgram assessment tool were selected to assess students' cardiovascular and muscular fitness, and skinfold tests were used to assess body composition. One control and 2 experimental groups were defined. The control group of students (n = 129) attended regular PE classes. One experimental group (n = 63) attended PE that was complemented by the MRT system. A second experimental group (n = 30) attended PE complemented by MRT and cardiovascular endurance training. With use of the selected Fitnessgram tests, post-test measurements were performed after 9 and 18 weeks of PE. At baseline, there were no significant differences among the 3 groups for most measures. Compared with baseline, the experimental groups improved significantly in all 6 fitness measures and showed more improvements than the control group in most fitness measures both at 9 and 18 weeks. None of the groups showed significant improvement in body composition. The results documented that an MRT-complemented PE program was effective in improving adolescents' muscular fitness. An 18-week combined MRT and cardiovascular endurance training program effectively improved cardiovascular and muscular fitness but was ineffective in improving adolescent body composition. An MRT-based exercise session requires minimal equipment and set-up and can be performed in a short period of time, and therefore it is suitable for application in regular PE settings.

Comparison of swim recovery and muscle stimulation on lactate removal after sprint swimming.

Neric FB, Beam WC, Brown LE, Wiersma LD.:

Journal of Strength and Conditioning research / National Strength & Conditioning Association, 23(9):2560-7, 2009. Exercise Physiology Laboratory, Department of Kinesiology, California State University, Fullerton, Fullerton, California, USA.

Competitive swimming requires multiple bouts of high-intensity exercise, leading to elevated blood lactate. Active exercise recovery has been shown to lower lactate faster than passive resting recovery but may not always be practical. An alternative treatment, electrical muscle stimulation, may have benefits similar to active recovery in lowering blood lactate but to date is unstudied. Therefore, this study compared submaximal swimming and electrical muscle stimulation in reducing blood lactate after sprint swimming. Thirty competitive swimmers (19 men and 11 women) participated in the study. Each subject completed 3 testing sessions consisting of a warm-up swim, a 200-yard maximal frontcrawl sprint, and 1 of 3 20-minute recovery treatments administered in random order. The recovery treatments consisted of a passive resting recovery, a submaximal swimming recovery, or electrical muscle stimulation. Blood lactate was tested at baseline, after the 200-yard sprint, and after 10 and 20 minutes of recovery. A significant interaction (p < 0.05) between recovery treatment and recovery time was observed. Blood lactate levels for the swimming recovery were significantly lower at 10 minutes (3.50 +/- 1.57 mmol.L-1) and 20 minutes (1.60 +/- 0.57 mmol.L-1) of recovery than either of the other 2 treatments. Electrical muscle stimulation led to a lower mean blood lactate (3.12 +/- 1.41 mmol.L-1) after 20 minutes of recovery compared with passive rest (4.11 +/- 1.35 mmol.L-1). Submaximal swimming proved to be most effective at lowering blood lactate, but electrical muscle stimulation also reduced blood lactate 20 minutes postexercise significantly better than resting passive recovery. Electrical muscle stimulation shows promise as an alternate recovery treatment for the purpose of lowering blood lactate.

Effect of concurrent resistance and endurance training on physiologic and performance parameters of well-trained endurance cyclists.

Levin GT, Mcguigan MR, Laursen PB

.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 23(8):2280-6, 2009. Vario Health Institute, Edith Cowan University, Joondalup, Australia.

The purpose of this study was to investigate the effect of concurrent resistance and endurance cycle training on physiologic and performance parameters of cyclists. Before and after a 6-week training intervention period, 14 well-trained male cyclists completed a maximal graded exercise test, a 30-km dynamic cycling test with 3 intermittent 250-m and 1-km sprints, and a 1 repetition maximum (1RM) squat test for the assessment of lower-limb strength. Subjects were allocated into 2 groups: a resistance training group (RT; n = 7) that completed a 6-week undulating, periodized resistance training program (3/wk) in conjunction with their regular cycle training and a control group (CON; n = 7) that maintained their usual cycle training. Upon completion of the training intervention, there was no change in graded exercise test parameters in either group, but the RT group showed a significantly greater increase in 1RM squat strength compared with CON (p < 0.05). Moreover, the change in 30-km time trial and sprinting performance did not differ between RT and CON, except for the final 1-km sprint where the percent change in 1-km final sprint performance was greater in CON (+11%) compared with RT (-5%). In conclusion, although concurrent resistance and endurance training in well-trained cyclists enhanced 1RM strength, it did not improve overall cycle time trial performance and in fact was shown to reduce 1-km final cycle sprint performance compared with a CON group performing their normal cycle training.

Comparison of resistance and concurrent resistance and endurance training regimes in the development of strength.

Shaw BS, Shaw I, Brown GA

.: Journal of Strength and Conditioning research / National Strength & Conditioning Association, 23(9):2507-14, 2009. Tshwane University of Technology, Department of Sport, Rehabilitation and Dental Sciences, Pretoria, Gauteng, Republic of South Africa.

Resistance and endurance training are often performed concurrently in most exercise programs and in rehabilitative settings in an attempt to acquire gains in more than 1 physiologic system. However, it has been proposed that by simultaneously performing these 2 modes of exercise training, the strength gains achieved by resistance training alone may be impaired. Thus, the aim of this study was to compare the effects of 16 weeks of resistance training and concurrent resistance and endurance training on muscular strength development in 38 sedentary, apparently healthy males (25 yr +/- 8 mo). Subjects were age-matched and randomly assigned to either a control (Con) group (n = 12), resistance training (Res) group (n = 13), or concurrent resistance and endurance training (Com) group (n = 13). After 16 weeks, no changes were found in the strength of the subjects in the Con group. Resistance training and concurrent resistance and endurance training significantly (p < or = 0.05) improved strength in all of the 8 prescribed exercises. The data also indicated that 16 weeks of concurrent resistance training and endurance training was as effective in eliciting improvements in strength as resistance training alone in previously sedentary males. As such, concurrent resistance and endurance training does not impede muscular strength gains and can be prescribed simultaneously for the development of strength in sedentary, apparently healthy males and thus may invoke all the physiologic adaptations of resistance and endurance training at once.

In-season effect of short-term sprint and power training programs on elite junior soccer players.

Mujika I, Santisteban J, Castagna C.: Journal of Strength and Conditioning research / National Strength & Conditioning Association, 23(9):2581-7, 2009. USP Araba Sport Clinic, Vitoria-Gasteiz, Basque Country, Spain.

The aim of this study was to examine the effects of 2 in-season short-term sprint and power training protocols on vertical countermovement jump height (with or without arms), sprint (Sprint-15m) speed, and agility (Agility-15m) speed in male elite junior soccer players. Twenty highly trained soccer players (age 18.3 +/- 0.6 years, height 177 +/- 4 cm, body mass 71.4 +/- 6.9 kg, sum skinfolds 48.1 +/- 11.4 mm), members of a professional soccer academy, were randomly allocated to either a CONTRAST (n = 10) or SPRINT (n = 10) group. The training intervention consisted of 6 supervised training sessions over 7 weeks, targeting the improvement of the players' speed and power. CONTRAST protocol consisted of alternating heavy-light resistance (15-50% body mass) with soccer-specific drills (small-sided games or technical skills). SPRINT training protocol used line 30-m sprints (2-4 sets of 4 x 30 m with 180 and 90 seconds of recovery, respectively). At baseline no difference between physical test performance was evident between the 2 groups (p > 0.05). No time x training group effect was found for any of the vertical jump and Agility-15m variables (p > 0.05). A time x training group effect was found for Sprint-15m performance with the CONTRAST group showing significantly better scores than the SPRINT group (7.23 +/- 0.18 vs. 7.09 +/- 0.20 m.s, p < 0.01). In light of these findings CONTRAST training should be preferred to line sprint training in the short term in young elite soccer players when the aim is to improve soccer-specific sprint performance (15 m) during the competitive season.

Effects of a back squat training program on leg power, jump, and sprint performances in junior soccer players.

Chelly MS, Fathloun M, Cherif N, Ben Amar M, Tabka Z, Van Praagh E.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 23(8):2241-9, 2009. Faculty of Medicine Ibn-El-jazzar, Sousse, Tunisia.

The aim of the present study was to investigate the effects of voluntary maximal leg strength training on peak power output (Wpeak), vertical jump performance, and field performances in junior soccer players. Twenty-two male soccer players participated in this investigation and were divided into 2 groups: A resistance training group (RTG; age 17 +/- 0.3 years) and a control group (CG; age 17 +/- 0.5 years). Before and after the training sessions (twice a week for 2 months), Wpeak was determined by means of a cycling force-velocity test. Squat jump (SJ), countermovement jump (CMJ), and 5-jump test (5-JT) performances were assessed. Kinematics analyses were made using a video camera during a 40-m sprint running test and the following running velocities were calculated: The first step after the start (V(first step)), the first 5 m (V(first 5 meters)), and between the 35 m and 40 m (V(max)). Back half squat exercises were performed to determine 1-repetition maximum (1-RM). Leg and thigh muscle volume and mean thigh cross-sectional area (CSA) were assessed by anthropometry. The resistance training group showed improvement in Wpeak (p < 0.05), jump performances (SJ, p < 0.05 and 5-JT, p < 0.001), 1-RM (p < 0.001) and all sprint running calculated velocities (p < 0.05 for both V(first step) and V(first 5 meters), p < 0.01 for V(max)). Both typical force-velocity relationships and mechanical parabolic curves between power and velocity increased after the strength training program. Leg and thigh muscle volume and CSA of RTG remained unchanged after strength training. Back half squat exercises, including adapted heavy loads and only 2 training sessions per week, improved athletic performance in junior soccer players. These specific dynamic constant external resistance exercises are highly recommended as part of an annual training program for junior soccer players.

Effects of in-season plyometric training within soccer practice on explosive actions of young players.

Meylan C, Malatesta D.:

Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 23(9):2605-13, 2009. Institute of Sport and Recreation Research New Zealand, AUT University, Auckland, New Zealand.

In soccer, explosive actions such as jumping, sprinting, and changes of direction are essential to optimal performance not only in adults, but also in children's games. The purpose of the present investigation was to determine the influence of a short-term plyometric training within regular soccer practice on explosive actions of early pubertal soccer players during the in-season. Fourteen children (13.3 +/- 0.6 years) were selected as the training group (TG) and 11 children (13.1 +/- 0.6 years) were defined as the control group (CG). All children were playing in the same league and trained twice per week for 90 minutes with the same soccer drills. The TG followed an 8-week plyometric program (i.e., jumping, hurdling, bouncing, skipping, and footwork) implemented as a substitute for some soccer drills to obtain the same session duration as CG. At baseline and after training, explosive actions were assessed with the following 6 tests: 10-meter sprint, agility test, 3 vertical jump tests (squat jump [SJ], countermovement jump [CMJ], contact test [CT] and multiple 5 bounds test [MB5]). Plyometric training was associated with significant decreases in 10-m sprint time (-2.1%) and agility test time (-9.6%) and significant increases in jump height for the CMJ (+7.9%) and CT (+10.9%). No significant changes in explosive actions after the 8-week period were recorded for the CG. The current study demonstrated that a plyometric program within regular soccer practice improved explosive actions of young players compared to conventional soccer training only. Therefore, the short-term plyometric program had a beneficial impact on explosive actions, such as sprinting, change of direction, and jumping, which are important determinants of match-winning actions in soccer performance.

Negative effect of static stretching restored when combined with a sport specific warm-up component.

Taylor KL, Sheppard JM, Lee H, Plummer N. Journal of Science and Medicine in Sport / Sports Medicine Australia, 12(6):657-61, 2009.

Department of Physiology, Australian Institute of Sport, Australia.

There is substantial evidence that static stretching may inhibit performance in strength and power activities. However, most of this research has involved stretching routines dissimilar to those practiced by athletes. The purpose of this study was to evaluate whether the decline in performance normally associated with static stretching pervades when the static stretching is conducted prior to a sport specific warm-up. Thirteen netball players completed two experimental warm-up conditions. Day 1 warm-up involved a submaximal run followed by 15 min of static stretching and a netball specific skill warm-up. Day 2 followed the same design; however, the static stretching was replaced with a 15 min dynamic warm-up routine to allow for a direct comparison between the static stretching and dynamic warm-up effects. Participants performed a countermovement vertical jump and 20m sprint after the first warm-up intervention (static or dynamic) and also after the netball specific skill warm-up. The static stretching condition resulted in significantly worse performance than the dynamic warm-up in vertical jump height (-4.2%, 0.40 ES) and 20m sprint time (1.4%, 0.34 ES) (p<0.05). However, no significant differences in either performance variable were evident when the skill-based warm-up was preceded by static stretching or a dynamic warm-up routine. This suggests that the practice of a subsequent high-intensity skill based warm-up restored the differences between the two warm-up interventions. Hence, if static stretching is to be included in the warm-up period, it is recommended that a period of high-intensity sport-specific skills based activity is included prior to the on-court/field performance.

Strength, power, speed, and agility of women basketball players according to playing position.

Delextrat A, Cohen D.: Journal of strength and conditioning research / National Strength & Conditioning Association, 23(7):1974-81, 2009.

Department of Health and Human Sciences, London Metropolitan University, London, England.

The aim of the present study was to investigate the effect of playing position on strength, power, speed, and agility performances of women basketball players. Thirty subjects playing at national level participated in this study. They were divided into 3 groups according to playing position: guards (positions 1 and 2), forwards (positions 3 and 4), and centers (position 5). Each subject performed 8 tests presented in a random order: The 30-second Wingate Anaerobic test (WAnT), isokinetic testing of the knee extensors, 2 types of jump tests, a 20-m sprint, the agility T-test, a suicide run, and a basketball chest pass. Statistical differences between playing positions were assessed using a 1-way analysis of variance (ANOVA) and Scheffe post hoc analyses. Results showed that guards performed significantly better than centers for the relative peak and mean power achieved during the WAnT (+13% and +16.9%, respectively), relative peak torque of knee extensors (+19.5%), single-leg jump (+21.8), suicide run (+7.5%), and agility T-test (+6.4%, p < 0.05). In addition, guards achieved significantly better performances than forwards in the suicide run test (+7.1%) and forwards were characterized by a greater peak torque of the knee extensors compared to centers (+22.1%). These results indicate that specific fitness training must be undertaken according to playing position. The ability to perform the suicide run, the single-leg jump, and the different movements involved in the agility T-test must be developed in guards. In contrast, speed over short distances and strength development of lower body and upper body should be performed by all playing positions.

Fitness profiling in soccer: physical and physiologic characteristics of elite players.

Sporis G, Jukic I, Ostojic SM, Milanovic D.: Journal of strength and conditioning research / National Strength & Conditioning Association, 23(7):1947-53, 2009.

Faculty of Kinesiology, University of Zagreb, Croatia.

The purpose of this study was to evaluate whether players in different positional roles have a different physical and physiologic profile. For the purpose of this study, physiologic measurements were taken of 270 soccer players during the precompetitive period of 2005/06 and the precompetitive period of 2006/07. According to the positional roles, players were categorized as defenders (n = 80), midfielders (n = 80), attackers (n = 80), and goalkeepers (n = 30). Analysis of variance (ANOVA) was use to determinate differences between team positions. Goalkeepers are the tallest and the heaviest players in the team. They are also the slowest players in the team when sprinting ability over 10 and 20 meters is required. Attackers were the quickest players in the team when looking at sprint values over 5, 10, and 20 meters. There were statistically significant differences between attacker and defenders when measuring vertical jump height by squat jump. Goalkeepers were able to perform better on explosive power tests (squat jump and countermovement jump) than players in the field. Midfielders had statistically significant superior values of relative oxygen consumption, maximal heart rate, maximal running speed, and blood lactate than defenders and attackers. Defenders had more body fat than attackers and midfielders (p < 0.05). Coaches are able to use this information to determine which type of profile is needed for a specific position. It is obvious that players in different positions have different physical and physiologic profiles. Experienced coaches can use this information in the process of designing a training program to maximize the fitness development of soccer players with one purpose only, to achieve success in soccer.

Effects of static stretching in warm-up on repeated sprint performance.

Sim AY, Dawson BT, Guelfi KJ, Wallman KE, Young WB.: Journal of Strength and Conditioning Research / National Strength & Conditioning Association, 23(7):2155-62, 2009.

School of Sport Science, Exercise and Health, University of Western Australia, Perth, Australia.

The aim of this study was to examine the effects of static stretching during warm-up on repeated sprint performance and also to assess any influence of the order in which dynamic activities (i.e., run-throughs and drills) and static stretching are conducted. Thirteen male team sport players completed a repeated sprint ability test consisting of three sets of maximal 6 x 20-m sprints (going every 25 seconds) after performing one of three different warm-up protocols in a within-subjects counterbalanced design. Each warm-up protocol involved an initial 1000-m jog, followed by either dynamic activities only (D), static stretching followed by dynamic activities (S-D), or dynamic activities followed by static stretching (D-S). First (FST), best (BST) and total (TST) 20-m sprint times were determined for each individual set of the repeated sprint ability test and overall (3 sets combined). Although consistent significant differences were not observed between trials for TST, BST, and FST, the mean values for TST in all individual sets and overall were generally slowest in the D-S condition (D = 60.264 +/- 1.127 seconds; S-D = 60.347 +/- 1.774 seconds; D-S = 60.830 +/- 1.786 seconds). This trend was supported by moderate to large effect sizes and qualitative indications of "possible" or "likely" benefits for TST, BST, and FST for the D and S-D warm-ups compared to D-S. No significant differences or large effect sizes were noted between D and S-D, indicating similar repeated sprint ability performance. Overall, these results suggest that 20-m repeated sprint ability may be compromised when static stretching is conducted after dynamic activities and immediately prior to performance (D-S).

The physiological effects of pre-event and midevent cooling during intermittent running in the heat in elite female soccer players.

Price MJ, Boyd C, Goosey-Tolfrey VL

.: Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et metabolism, 34(5):942-9, 2009.

Department of Biomolecular and Sports Science, Faculty of Health and Life Sciences, Coventry University, Priory Street, Coventry, UK.

The purpose of this study was to examine the effects of both pre-exercise and combined pre-exercise and midexercise cooling strategies during simulated match play in elite female soccer players in the heat. Eight elite female soccer players performed two 45 min periods of intermittent running separated by 15 min seated rest on 3 separate occasions (30.6 +/- 0.2 degrees C, 63.4 +/- 2.5% relative humidity). Participants undertook a no-cooling (CON) or ice-vest cooling for 20 min pre-exercise (PRE) or both pre-exercise and during the 15 min rest period (PRE+MID). Rectal temperature (Tre), skin temperatures, and heart rate were monitored continuously. Mean skin temperature (TMS) and heat storage were calculated. Significant interactions (trial x time) were observed for the change in Tre from rest, TMS, and heat storage (p < 0.05). The change in Tre from rest was greater during CON when compared with PRE and PRE+MID from 35 min until the end of exercise (p < 0.05). When compared with CON (p < 0.05), TMS was lower after precooling (PRE and PRE+MID) and during the 15 min rest period and the first 5 min of the second exercise bout for PRE+MID. Heat storage was also lower after precooling (PRE and PRE+MID) (p < 0.05) and from 60 min until the end of exercise for PRE+MID (p < 0.05) and until 85 min and again at 95 min during PRE (p < 0.05). The results of this study suggest that both cooling strategies were effective in reducing thermal strain during intermittent exercise in the heat. However, PRE+MID cooling was more effective than PRE cooling in offsetting heat storage.

Match demands of professional Futsal: a case study.

Castagna C, D'Ottavio S, Granda Vera J, Barbero Alvarez JC

. Journal of Science and Medicine in Sport / Sports Medicine Australia, 12(4):490-4, 2009 .

Corso di Laurea in Scienze Motorie, Università di Roma Tor Vergata, Italy.

Despite its popularity and competitive status there have been only few scientific studies that have examined Futsal in professional players. Consequently the aim of this study was to examine the physiological responses and activity pattern to Futsal simulated game-play in professional players. Eight full-time professional outfield Futsal players volunteered for this study: age 22.4 (95% CI 18.8-25.3) years, body mass 75.4 (60-91) kg, height 1.77 (1.59-1.95) m and VO2max 64.8 (53.8-75.8) ml kg(-1) min(-1). Physiological measurements were assessed during highly competitive training games (4x10-min quarters) and consisted of game VO2, game blood-lactate concentration ([la](b)) and game heart rates (HRs). Game activities were assessed using a computerised video-analysis system. During simulated game-play players attained 75% (59-92) and 90% (84-96) of VO2max and HR(max), respectively. Mean game VO2 was 48.6 (40.1-57.1) ml kg(-1) min(-1). Peak game VO2 and HRs were 99% (88-109) and 98% [90-106] of laboratory maximal values, respectively. Players spent 46 and 52% of the playing time at exercise intensities higher than 80 and 90% of VO2max and HR(max), respectively. Mean [la](b) was 5.3 (1.1-10.4) mmol l(-1). Players covered 121 (105-137) m min(-1) and 5% (1-11) and 12% (3.8-19.5) of playing time spent performing sprinting and high-intensity running, respectively. On average players performed a sprint every approximately 79 s during play. These results show that Futsal played at professional level is a high-intensity exercise heavily taxing the aerobic and anaerobic pathways.

Effect of warm-up on run time to exhaustion.

Wittekind AL, Beneke R. Journal of science and medicine in sport / Sports Medicine Australia, 12(4):480-4, 2009.

Australia Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom.

It is not known whether warm-up protocols typically employed by athletes are beneficial to performance. The aim of this study was to investigate the effect of warm-up on a perimaximal run to exhaustion, VO2 kinetics, energy metabolism and running economy. Nine male distance runners ran to exhaustion at a speed corresponding to 105% maximal oxygen uptake (VO2max) after each of three different warm-up protocols: no warm-up (NW), jog warm-up (WM), or jog with strides (WH). Warm-up did not affect pre-run blood lactate concentration (BLC), BLC-increase (DeltaBLC), net oxygen consumption, or running economy. WH increased the amplitude of the primary VO2 response (mean (confidence intervals of difference); 4083 ml min(-1) vs. 3763 ml min(-1) (-638, -2)), with no change in the time constant; reduced the rate of BLC-increase (DeltaBLC-rate) (0.02 mmol l(-1) s(-1) vs. 0.03 mmol l(-1) s(-1) (0.003, 0.01)); reduced anaerobic lactic power (109 W vs. 141 W (13, 51)); reduced the relative anaerobic lactic energy contribution (7.0% vs. 9.1% (0.8, 3.4)) compared to NW. The reduction in anaerobic power associated with DeltaBLC-rate between NW and WH was significantly correlated with the increase in aerobic power associated with the primary amplitude (r=0.674, p<0.05). Despite these theoretically beneficial metabolic effects, WH did not significantly increase time to exhaustion vs. NW (290 s vs.316 s (-77, 43)) but might be considered in events where the winning margin is often small.

Strength profiles of shoulder rotators in healthy sport climbers and nonclimbers. Wong, E. K., Ng, G. Y.: The Hong Kong Polytechnic University, Hong Kong, People's Republic of China. Journal of athletic training, 44(5):527-30, 2009. OBJECTIVE: To establish the isokinetic strength profiles and work ratios of the shoulder internal and external rotators in sport climbers and to compare them with these profiles and ratios in nonclimbers. We hypothesized that the strength profiles of the shoulder rotators were different between sport climbers and nonclimbers. DESIGN: Cross-sectional study. SETTING: Exercise science laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirty-one experienced sport climbers and 27 nonclimbers. MAIN OUTCOME MEASURE(S): We tested all participants by measuring the isokinetic concentric and eccentric work output of their shoulder rotators in the middle 110 degrees of shoulder rotation. We measured mean conventional work ratios of concentric external rotation (ER) to internal rotation (IR) (con ER:IR) and eccentric ER to IR (ecc ER:IR), and we measured mean functional work ratios of eccentric ER to concentric IR (ecc ER:con IR) and eccentric IR to concentric ER (ecc IR:con ER). RESULTS: All work ratios were different between the 2 groups (P < .001). In the climbers, the conventional work ratios were smaller than 1 for con ER:IR (0.79) and ecc ER:IR (0.88), whereas for the nonclimbers, the ratios were 1.03 and 1.13, respectively. The functional work ratio of ecc ER:con IR was smaller for the climbers (1.05) than for the nonclimbers (1.30), but the functional work ratio of ecc IR:con ER was larger for the climbers (1.58) than for the nonclimbers (1.17). CONCLUSIONS: The difference in work ratios of the shoulder rotators between participant groups might be due to training-induced changes in the shoulder rotation muscles of sport climbers. The clinical implication of this strength difference in shoulder IR and ER in climbers has yet to be examined.

Running performance, not anthropometric factors, is associated with race success in a Triple Iron Triathlon.Knechtle, B., Kohler, G.: Gesundheitszentrum St Gallen, St Gallen, Switzerland.British journal of Sports Medicine, 43(6):437-41, 2009.

OBJECTIVES: To investigate the influence of anthropometric parameters on race performance in ultra-endurance triathletes. DESIGN: Descriptive field study. SETTING: The Triple Iron Triathlon Germany 2006 in Lensahn over 11.6 km swimming, 540 km cycling and 126.6 km running. SUBJECTS: 17 male Caucasian triathletes (mean (SD) 39.2 (7.5) years, 80.7 (8.9) kg, 178 (5) cm, BMI 25.4 (2.4) kg/m(2)). INTERVENTIONS: None. MAIN OUTCOME MEASUREMENTS: Determination of body mass, body height, skin fold thicknesses, circumferences of extremities, as well as calculation of body mass index (BMI), skeletal muscle mass (SM), per cent SM (%SM) and per cent body fat (%BF) in order to correlate measured and calculated anthropometric parameters with race performance. RESULTS: Body mass, body height, skin fold thicknesses, circumferences of extremities, BMI, %SM and %BF had no effect (p>0.05) on race performance. No significant correlation (p>0.05) was observed between total race time and any of the directly measured and calculated anthropometric properties. A significant correlation (p0.05) was shown between swimming time and total race time. CONCLUSIONS: There is no significant association between anthropometric parameters and race performance in ultra-endurance triathletes. Running performance rather than cycling performance seems to be the most important factor in order to be successful in a Triple Iron Triathlon. Swimming performance seems to be of low importance.

Neuromuscular adaptations to training, injury and passive interventions: implications for running economy.

Bonacci, J., Chapaman, A. et al: Musculoskeletal Pain and Injury Research Unit, University of Queensland, Brisbane, Queensland, Australia.

Heart rate-based lactate minimum test: a reproducible method. Strupler, M., Muleller, G., Perret, C.: Swiss Paraplegic Centre Nottwil 6207, Switzerland.British journal of Sports Medicine, 43(6):432-6, 2009 OBJECTIVE: To find the individual intensity for aerobic endurance training, the lactate minimum test (LMT) seems to be a promising method. LMTs described in the literature consist of speed or work rate-based protocols, but for training prescription in daily practice mostly heart rate is used. The aim of the present study was to investigate the reproducibility of a new heart rate-based LMT protocol. DESIGN: 20 subjects each underwent four LMTs on a cycle ergometer. The LMT consisted of a first part (Conconi test) to induce lactate accumulation and a second part (incremental protocol) with stages of 5 min starting beyond the aerobic threshold. During these stages work rate was adjusted to reach predetermined heart rates, which were calculated for every single test from heart rate (HR) at rest and maximum HR. Lactate was measured after each stage to define the lactate minimum (LM) and the corresponding HR. SETTING: Institute of Sports Medicine. PARTICIPANTS: 20 healthy and endurance-trained individuals (13 men, seven women). MAIN OUTCOME MEASURES: Reproducibility of heart rate at LM. RESULTS: The reproducibility of heart rate at LM was high (coefficient of variation (CV) = 2.1%). The reproducibility of work rate at LM was good (CV = 6.7%). CV for lactate concentrations at LM was 17.4%. High interindividual differences at LM were found in heart rate (range 149-178 beats/min) and lactate levels (range 1.2-6.8 mmol/l). CONCLUSION: The LMT using a heart rate-based protocol is a reproducible method of assessing HR at an exercise intensity where an equilibrium exists between blood lactate accumulation and elimination.

High-intensity training in football. Iaia, F.M., Rampinini, E., Bangsbo, J.: Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark.International journal of sports physiology and performance, 4(3):291-306, 2009.

This article reviews the major physiological and performance effects of aerobic high-intensity and speed-endurance training in football, and provides insight on implementation of individual game-related physical training. Analysis and physiological measurements have revealed that modern football is highly energetically demanding, and the ability to perform repeated high-intensity work is of importance for the players. Furthermore, the most successful teams perform more high-intensity activities during a game when in possession of the ball. Hence, footballers need a high fitness level to cope with the physical demands of the game. Studies on football players have shown that 8 to 12 wk of aerobic high-intensity running training (> 85% HR(max)) leads to VO2(max) enhancement (5% to 11%), increased running economy (3% to 7%), and lower blood lactate accumulation during submaximal exercise, as well as improvements in the yo-yo intermittent recovery (YYIR) test performance (13%). Similar adaptations are observed when performing aerobic high-intensity training with small-sided games. Speed-endurance training has a positive effect on football-specific endurance, as shown by the marked improvements in the YYIR test (22% to 28%) and the ability to perform repeated sprints (approximately 2%). In conclusion, both aerobic and speed-endurance training can be used during the season to improve high-intensity intermittent exercise performance. The type and amount of training should be game related and specific to the technical, tactical, and physical demands imposed on each player.

Gender comparison of physiologic and perceptual responses in recreational marathon runners.

PURPOSE: The aim of this investigation was to compare gender differences in physiologic and perceptual responses during a 1-h run at recent marathon pace and running economy at three speeds in recreational marathon runners. METHODS: In a counterbalanced design, 10 men and 10 women completed a 1-h treadmill run and a running economy test. Treadmill speed for the 1-h run ranged from 141 to 241 mmin(-1) and 134, 168, and 188 m x min(-1) for running economy. Physiologic parameters (oxygen uptake, carbon dioxide production, pulmonary ventilation, and heart rate) and perceived exertion were measured. Repeated-measures ANOVA was used to compare any gender differences (P < .05) during the 1-h run and a two-way ANOVA was used to compare running economy. With this sample, estimated marathon energy expenditure, body composition, and maximal physiologic function was reported. RESULTS: With the exception of an allometric expression of VO2 (mL x min(-1) kg BW(-0.75)), similar gender physiologic and perceptual responses were found during the 1-h run. Although not significant, the females exercised at a higher percent VO2(max) (8% to 9%) during the run. Similar gender differences were also noted during the running economy tests. CONCLUSIONS: Although the male runners completed a recent marathon significantly faster than the females, similar gender physiologic and perceptual responses were generally found during the 1-h treadmill run and the running economy tests.

Effect of local cold-pack application on systemic anabolic and inflammatory response to sprint-interval training: a prospective comparative trial.

Nemet, D., Meckel, Y., et al.. Pediatric Department, Meir Medical Center, Child Health & Sport Center, Sackler School of Medicine, Tel-Aviv University, Kfar-Saba 44821, Israel.

European journal of applied physiology, 107(4):411-7, 2009. We evaluated the effect of cold ice-pack application following a brief sprint-interval training on the balance between anabolic mediators [growth hormone (GH), insulin-like growth factor-I (IGF-I), testosterone], catabolic markers (cortisol, IGFBP-1), and circulating pro [Interlukin-6 (IL-6) and IL-1beta]- and anti-inflammatory cytokines [IL-1 receptor antagonist (IL-1ra)]. Twelve males, elite junior handball players performed 4 x 250 m treadmill run, at 80% of each individual's maximal speed, followed by a rest period with and without local cold-pack application. Pre, immediately post, and 60-min post-exercise blood samples were drawn. Exercise was associated with a significant increase in IL-6, GH, IGFBP-3, and testosterone levels. Local cold-pack application was associated with significant decreases in IL-1beta, IL-1ra, IGF-I, and IGFBP-3 and a greater increase of IGFBP-1 during recovery. Local ice therapy immediately following sprint-interval training was associated with greater decreases in both pro- and anti-inflammatory cytokines and anabolic hormones supporting some clinical evidence for possible negative effects on athletic performance.