Protein intake that exceeds the recommended daily allowance is widely accepted for both endurance and power athletes. However, considering the variety of proteins that are available much less is known concerning the benefits of consuming one protein versus another. The purpose of this paper is to identify and analyze key factors in order to make responsible recommendations to both the general and athletic populations. Evaluation of a protein is fundamental in determining its appropriateness in the human diet. Proteins that are of inferior content and digestibility are important to recognize and restrict or limit in the diet. Similarly, such knowledge will provide an ability to identify proteins that provide the greatest benefit and should be consumed. The various techniques utilized to rate protein will be discussed. Traditionally, sources of dietary protein are seen as either being of animal or vegetable origin. Animal sources provide a complete source of protein (i.e. containing all essential amino acids), whereas vegetable sources generally lack one or more of the essential amino acids. Animal sources of dietary protein, despite providing a complete protein and numerous vitamins and minerals, have some health professionals concerned about the amount of saturated fat common in these foods compared to vegetable sources. The advent of processing techniques has shifted some of this attention and ignited the sports supplement marketplace with derivative products such as whey, casein and soy. Individually, these products vary in quality and applicability to certain populations. The benefits that these particular proteins possess are discussed. In addition, the impact that elevated protein consumption has on health and safety issues (i.e. bone health, renal function) are also reviewed.
We determined whether ultra-runners in a multi-stage ultra- endurance run lose body mass, fat mass, skeletal muscle mass or total body water in a descriptive field study at the 'Deutschlandlauf' 2007 a 1,200 km run within 17 consecutive days with 10 male non-professional Caucasian ultra-runners (mean ± SD, 43.8 ± 6.2 years, 73.8 ± 6.0 kg body mass, 1.77 ± 0.05 m body height, BMI 23.3 ± 1.8 kg·m(-2)). Body mass, fat mass, skeletal muscle mass, lean body mass and percent total body water were determined using bioelectrical impedance analysis and the anthropometric method before the race and after each stage. In addition, urinary specific gravity was measured in order to quantify hydration status. Fat mass (bioelectrical impedance analysis) decreased by 3.9 kg (p < 0.05), skeletal muscle mass (anthropometric method) decreased by 2.0 kg (p < 0.05) whereas percent total body water increased by 6.1 % (p < 0.05) by the end of the race. Ultra-runners in a multi-stage ultra-endurance event over 1,200 km, with 17 consecutive stages, showed a cumulative increase in percent total body water, a decrease in skeletal muscle mass and a decrease in fat mass, depending upon the method used. We presume that the eccentric component of running leads to damage of skeletal muscle, leading to rhabdomyolysis, with impaired renal function. Key pointsUltra-runners in a multi-stage ultra-endurance run over 1,200 km in 17 consecutive stages suffered a decrease in fat mass, skeletal muscle mass and an increase in total body water, whereas overall body mass showed no change.
The mechanisms of anterior cruciate ligament (ACL) injuries are still inconclusive from an epidemiological standpoint. An epidemiological approach in a large sample group over an appropriate period of years will be necessary to enhance the current knowledge of the ACL injury mechanism. The objective of the study was to investigate the ACL injury occurrence in a large sample over twenty years and demonstrate the relationships between the ACL injury occurrence and the dynamic knee alignment at the time of the injury. We investigated the activity, the injury mechanism, and the dynamic knee alignment at the time of the injury in 1,718 patients diagnosed as having the ACL injuries. Regarding the activity at the time of the injury, "competition "was the most common, accounting for about half of all the injuries. The current result also showed that the noncontact injury was the most common, which was observed especially in many female athletes. Finally, the dynamic alignment of "Knee-in & Toe- out "(i.e. dynamic knee valgus) was the most common, accounting for about half. These results enhance our understanding of the ACL injury mechanism and may be used to guide future injury prevention strategies. Key pointsWe investigated the situation of ACL injury occurrence, especially dynamic alignments at the time of injury, in 1,718 patients who had visited our institution for surgery and physical therapy for twenty years.Our epidemiological study of the large patient group revealed that "knee-in & toe-out "alignment was the most frequently seen at the time of the ACL injury.From an epidemiological standpoint, we need to pay much attention to avoiding "Knee-in & Toe-out "alignment during sports activities.
This study aimed to identify the effect of different stroke rates on various kinematic parameters during 1000 m outrigger canoeing. Sixteen, experienced female outrigger canoeists completed three 1000 m outrigger ergometer time trials, one trial each using a self-selected, a Hawaiian (≤ 55 strokes·min(-1)) and a Tahitian (≥ 65 strokes·min(-1)) stroke rate. Stroke rate, stroke length, stroke time, proportion of time spent in propulsion and recovery, torso flexion angle and 'twist' were measured and compared with repeated measures ANOVAs. Stroke rate, stroke length and stroke time were significantly different across all interventions (p < 0.05) despite no difference in the percentage of time spent in the propulsive and recovery phases of the stroke. Stroke length and stroke time were negatively correlated to stroke rate for all interventions (r = -0.79 and -0.99, respectively). Female outrigger canoeists maintain consistent stroke kinematics throughout a 1000 m time trial, most likely as a learned skill to maximize crew paddling synchrony when paddling on-water. While the Hawaiian stroke rate resulted in the greatest trunk flexion movement and 'twist' action, this potential increased back injury risk may be offset by the slow stroke rate and long stroke length and hence slow rate of force development. Key pointsAs outrigger canoeing stroke rate increased, stroke length decreased but the proportion of the stroke time spent in the propulsive phase was kept consistent.The outrigger canoeing technique involved a similar amount of torso flexion-extension movement to rowing, with an additional twisting motion of the torso evidenced, that may increase the risk of back injury.A slower stroke rate, to lessen the rate of force production, may minimize potential back injury in outrigger canoeists and dragon boat paddlers.
The aim of this study was to examine the effects of different pedalling cadences on the performance of a subsequent 10km treadmill run. Eight male triathletes (age 38.9 ± 15.4 years, body mass 72.2 ± 5.2 kg, and stature 176 ± 6 cm; mean ± SD) completed a maximal cycling test, one isolated run (10km), and then three randomly ordered cycle-run sessions (65 minutes cycling + 10km run). During the cycling bout of the cycle-run sessions, subjects cycled at an intensity corresponding to 70% Pmax while maintaining one of three cadences, corresponding to preferred cadence (PC), PC+15% (fast cadence) and PC-15% (slow cadence). Slow, preferred and fast cadences were 71.8 ± 3.0, 84.5 ± 3.6, and 97.3 ± 4.3 rpm, respectively (mean ± SD). Physiological variables measured during the cycle-run and isolated run sessions were VO2, VE, RER, HR, RPE, and blood lactate. Biomechanical variables measured during the cycle-run and isolated run sessions were running velocity, stride length, stride frequency, and hip and knee angles at foot-strike and toe-off. Running performance times were also recorded. A significant effect of prior cycling exercise was found on 10km running time (p = 0.001) without any cadence effect (p = 0.801, ω2 = 0.006) (49:58 ± 8:20, 49:09 ± 8:26, 49:28 ± 8:09, and 44:45 ± 6:27 min·s-1 for the slow, preferred, fast, and isolated run conditions, respectively; mean ± SD). However, during the first 500 m of the run, running velocity was significantly higher after cycling at the preferred and fast cadences than after the slow cadence (p < 0.05). Furthermore, the slow cadence condition was associated with a significantly lower HR (p = 0.012) and VE (p = 0.026) during cycling than in the fast cadence condition. The results confirm the deterioration in running performance completed after the cycling event compared with the isolated run. However, no significant effect of cycling cadence on running performance was observed within the cadence ranges usually used by triathletes.
The aim of this study was to characterize the backstroke swimming technique of 11-13 year-old swimmers when performing at very high intensity. A sample of 114 swimmers was divided into four groups regarding maturational and gender effect, who performed 25-m backstroke swimming at 50-m pace. Using two underwater cameras the general biomechanical parameters (speed, stroke rate, stroke length and stroke index), the arm stroke phases and two indexes of arm coordination (Index of Coordination 1, which characterizes the continuity between propulsive phases of each arm and Index of Coordination 2 that evaluates the simultaneity between the beginning of the pull of one arm and of the recovery of the other arm) were measured. Post-pubertal swimmers achieved higher values of speed (1.06 ± 0.14 and 1.18 ± 0.14 m·s-1 for pubertal and 1.13 ± 0.14 and 1.24 ± 0.12 m·s-1 for post-pubertal girl and boy swimmers, respectively), stroke length (1.64 ± 0.26 and 1.68 ± 0.25 m·cycle-1 for pubertal and 1.79 ± 0.22 and 1.75 ± 0.27 m·cycle-1 for postpubertal girls and boys, respectively) and stroke index. Regarding genders, male were faster than female swimmers. Boys also showed a higher stroke rate and stroke index than girls, who achieved higher results in the ratio between stroke length and arm span. As it was expected, no hand lag time was noticed in young swimmers. Although no differences were noticed between genders, the Index of Coordination 1 was in catch-up mode (-9.89 ± 3.16 and -10.16 ± 3.60 % for girls and -9.77 ± 2.93 and -10.39 ± 2.44 % for boys pubertal and post-pubertal, respectively) and the Index of Coordination 2 was in superposition mode (1.86 ± 4.39 and 2.25 ± 2.25 % from girls and 1.72 ± 2.62 and 1.95 ± 2.95 % for boys, pubertal and post-pubertal, respectively).
There is a paucity of evidence regarding the use of injury prevention programmes for preadolescents participating in sport. "The 11" injury prevention programme was developed by FIFA's medical research centre (F-MARC) to help reduce the risk of injury in football players aged 14 years and over. The aim of this study was to determine the suitability and effectiveness of "The 11" for younger football players. Twenty-four [12 experimental (EXP), 12 control (CON)] young football players (age 10.4 ± 1.4 yr) participated. The EXP group followed "The 11" training programme 5 days per week, for 6 weeks, completing all but one of the 10 exercises. Prior to, and after the intervention, both EXP and CON groups performed a battery of football-specific physical tests. Changes in performance scores within each group were compared using independent t-tests (p ≤ 0.05). Feedback was also garnered on the young players' perceptions of "The 11". No injuries occurred during the study in either group. Compliance to the intervention was 72%. Measures of leg power (3 step jump and counter-movement jump) increased significantly (3.4 and 6.0% respectively, p < 0.05). Speed over 20 m improved by 2% (p < 0.05). Most players considered "The 11" beneficial but not enjoyable in the prescribed format. Given the observed improvements in the physical abilities and the perceived benefits of "The 11", it would appear that a modified version of the programme is appropriate and should be included in the training of young football players, for both physical development and potential injury prevention purposes, as well as to promote fair play. To further engage young football players in such a programme, some modification to "The 11" should be considered.
The FIFA 11+ is a structured warm-up programme specially designed to prevent injuries among football players from age 14 years and above. However, studies to prove its efficacy are generally few and it is yet to be tested in male youth footballers and among African players. The purpose of the study was to examine the efficacy of the FIFA 11+ programme in reducing the risk of injuries among male youth football players of the Lagos Junior League. A cluster randomised controlled trial was conducted. All the 20 teams (414 players aged 14 -19 years) in the Premier League division were block-randomised into either an intervention (INT) or a control (CON) group. The INT group performed the FIFA 11+ exercises as warm-up during training sessions and the CON group performed usual warm-up. Participating teams were prospectively followed through an entire league season of 6 months in which they were visited every week to assess injured players for time-loss injuries in both groups. The primary outcomes were any injury to the players, injuries by type of exposure and injuries specific to the lower extremities. The secondary outcomes were injuries reported by body location, aetiology, mechanism and severity. In total, 130 injuries were recorded affecting 104 (25%) of the 416 players. Team and player compliance with the INT was 60% and 74% respectively. Based on the primary outcome measures of the study, the FIFA 11+ programme significantly reduced the overall rate of injury in the INT group by 41% [RR = 0.59 (95% CI: 0.40 - 0.86; p = 0.006)] and all lower extremity injuries by 48% [RR = 0.52 (95% CI: 0.34 - 0.82; p = 0.004)]. However, the rate of injury reduction based on secondary outcomes mostly did not reach the level of statistical significance. The FIFA 11+ programme is effective in reducing the rates of injuries in male youth football players.
The aims of this study were to assess levels and patterns of physical activity (PA) in relation to age and regular sport activity, and to examine its relationship to physical fitness in trained and untrained boys. One hundred forty-seven 11-to 15-year-old boys (73 trained and 74 untrained) participated in this study. Trained boys, comprised of 26 soccer, 25 handball and 22 volleyball players, had been training regularly for at least one year. The intensity, duration and frequency of PA were assessed from four complete days of heart rate monitoring with 15-seconds sampling intervals. Aerobic fitness was assessed by determining peakVO2 with a portable breath-by-breath gas analyzer (Cosmed K4b2) and the running speeds at fixed lactate concentrations during an incremental running test. Anaerobic fitness was evaluated with the Wingate Anaerobic Test. Skin fold thicknesses from eight sites and Tanner stages of pubic hair were also obtained. Based on 15-s heart rate data, instead of continuous activity, multiple short bouts of moderate and vigorous PA, lasting up to one minute, were characteristic of daily PA patterns of both trained and untrained boys. PA levels of trained boys were higher than untrained boys (p < 0.01) and the levels of PA decreased with age and maturation in both groups (p < 0.05). Daily PA variables were related to body fatness in both groups (p < 0.05), but the relationships were not consistent in the trained group. Daily PA variables were also related to aerobic fitness in the untrained group (p < 0.05) and these relationships were somewhat better with vigorous PA, whereas in the trained group, none of the PA variables were related to any of the aerobic fitness indices (p > 0.05). No relationship was observed between PA variables and anaerobic fitness in either group (p> 0.05). It seems that such relationships may somewhat depend on the fitness level of the subjects.
The preseason in soccer is a short period of 6-8 weeks where conditional abilities, technical and tactical elements need to be trained. Therefore, time is lacking to perform long term preparation periods for different abilities, especially endurance training. There is evidence that the implementation of high-intensity shock microcycles in preseason training could be one way to improve physical performance in a short period of time. Therefore, the purpose of the present study was to examine the effects and the sustainability of a high-intensity shock microcycle on soccer specific performance. Over 2 weeks, 12 male soccer players (26.1 ± 4.5 years) performed 12 high-intensity training (HIT) sessions in addition to their usual training. Before (pre), 6 days (6d) and 25 days (25d) after training, subjects performed Counter Movement Jump (CMJ), Repeated-Sprint Ability (RSA) test and Yo-Yo Intermittent Recovery Test Level 2 (YYIR2). Mean sprint time (RSAMean) (cohen's d = -1.15), percentage decrement score (RSAIndex) (cohen's d = -1.99) and YYIR2 (cohen's d = +1.92) improved significantly from pre to 6d. 25d after, values showed a significant reduction for YYIR2 (cohen's d = -0.81) and small to moderate but not significant increase for RSAMean (cohen's d = +0.37) and RSAIndex (cohen's d = +0.7) compared to 6d values. Small but no significant increases were found for CMJ (cohen's d = +0.33) and no significant and substantial changes were found for RSABest (cohen's d = -0.07) from pre to 6d. For competitive soccer players, block periodization of HIT offers a promising way to largely improve RSA and YYIR2 in a short period of time. Despite moderate to large decreases in RSAIndex and YYIR2 performance in the 19 day period without HIT, values still remained significantly higher 25d after the last HIT session compared to pre-values. However, it might be necessary to include isolated high-intensity sessions after a HIT training block in order to maintain the higher level of YYIR2 and RSAIndex performance. Key pointsHIT shock microcycle increases performance in semi-professional soccer players in a short period of time.Despite moderate to large decreases in performance in the 19 day period without HIT, values still remained significantly higher 25d after the last HIT session compared to pre-values.This kind of training block increases YYIR2 performance and the ability to repeated sprints, based on the RSAIndex.
The main purpose of this study was the identification of the current pedometer determined physical activity levels of a large sample of 9 -14 years old Greek schoolchildren and the determination of the association between daily step counts and body mass index through the comparison of step counts among overweight, obese and normal-weight children. A total of 532 children (263 boys and 269 girls) were measured for height and weight. Their activity levels were analyzed using pedometers to measure mean steps for 7 consecutive days. Overweight and obese status was determined using the international reference standard (Cole et al., 2000). According to data analysis mean step counts ranged from 15371 to10539 for boys and from 11536 to 7893 for girls. Steps per day were significantly more for boys compared to girls. Children with normal weight performed significantly more steps per day compared to their overweight and obese classmates. Daily step counts reported in this study for 9 -14 year old schoolchildren were relatively low when compared to step counts from other European countries. Only 33.9% of the participants satisfied the body mass index referenced standards for recommended steps per day. Finally, the results of this study provide baseline information on youth pedometer determined physical activity and on youth body mass index levels. High prevalence of low daily step counts and BMI determined obesity was revealed prompting for further exploration of the relationship between objectively measured physical activity and adiposity in particular for children and adolescents that experience both health risk factors.
The purpose of the study was to assess the effects of sodium citrate ingestion on the metabolic response to exercise and performance in a 1500-m competitive run in trained female middle-distance runners in field conditions. Seventeen athletes (mean (± SD) aged 18.6 ± 2.5 years, VO 2max 55.2 ± 7.6 ml·kg-1·min -1) competed in two 1500-m races following ingestion of 0.4 g·kg-1 body mass of sodium citrate (CIT) and placebo (PLC - 1.0% solution of NaCl). The two substances, CIT and PLC were administered in 800 ml of solution in a randomly assigned double-blind crossover manner. Capillary blood samples were analysed for lactate, glucose, haemoglobin and haematocrit before administering the solutions (baseline) as well as before and after both 1500-m races. The athletes' times for trials CIT and PLC were 321.4 ± 26.4 and 317.4 ± 22.5 s, respectively (p > 0.05). A greater relative increase in plasma volume after administering the experimental solution, an increased body mass (by 0.4 kg; p = 0.006) immediately before the race and a restrained increase in blood glucose concentration (by 2.5 ± 1.2 mmol·l-1 vs 3.4 ± 0.8 mmol·l-1; p = 0.002) during the race were observed in the CIT trial compared to the PLC. A significant relationship was observed between body mass of the subjects immediately before the race and performance time (r = 0.374; p = 0.029). There were no between-treatment differences in heart rate in any stage of the run or in blood lactate accumulation during the race (final concentration of lactate was 14.4 ± 3.0 mmol·l-1 and 13.4 ± 2.5 mmol·l-1 (p > 0.05) in the CIT and PLC trials, respectively). The results suggest that sodium citrate induces an increase in water retention before exercise and may modify carbohydrate metabolism in high intensity running, but does not improve performance in 1500-m competitive run in female middle-distance runners.
We investigated the relationship between age and muscle size in both the appendicular and trunk regions of 1507 Japanese men and women aged 20 to 95 years. Seven hundred twenty-two men (young [aged 20-39 years], n = 211; middle-aged [aged 40-59 years], n = 347; and old [aged 6095 years], n = 164) and 785 women (young, n = 207; middle-aged, n = 341; and old, n = 237) were recruited for this cross-sectional study. Muscle thickness (MTH) and subcutaneous fat thickness (FTH) were measured by ultrasound at 8 sites on the anterior and posterior aspects of the body. MTH was expressed in terms relative to limb length (MTH/L) or height (MTH/Ht). Percent body fat was estimated from FTH, and fat-free mass (FFM) was calculated. In men, a graded decrease in FFM was found in all age groups. In women, FFM was similar in the young and middle-aged groups, but was lower in the oldest group. Age was significantly and inversely correlated with FFM in men (r = -0.358, p < 0.01), but not in women (r = -0.08). On the other hand, age was strongly and inversely correlated with quadriceps MTH/L (men, r = -0.529; women, r = -0.489; both p < 0.001) and abdomen MTH/Ht (men, r = -0.464; women, r = -0.446; both p < 0.001) in both men and women, while there were only weak correlations between age and other lower limb and trunk sites. Our results indicated that sarcopenia is observed as a site-specific loss of skeletal muscle mass, especially for the quadriceps and abdominal muscles, in Japanese men and women aged 20 to 95 years.
The aim of the present study was to identify the game-related statistics which discriminate between winning and losing teams in under-16 years old male basketball games. The sample gathered all 122 games in the 2004 and 2005 Under-16 European Championships. The game-related statistics analysed were the free-throws (both successful and unsuccessful), 2- and 3-points field-goals (both successful and unsuccessful) offensive and defensive rebounds, blocks, assists, fouls, turnovers and steals. The winning teams exhibited lower ball possessions per game and better offensive and defensive efficacy coefficients than the losing teams. Results from discriminant analysis were statistically significant and allowed to emphasize several structure coefficients (SC). In close games (final score differences below 9 points), the discriminant variables were the turnovers (SC = -0.47) and the assists (SC = 0.33). In balanced games (final score differences between 10 and 29 points), the variables that discriminated between the groups were the successful 2-point field-goals (SC = -0.34) and defensive rebounds (SC = -0. 36); and in unbalanced games (final score differences above 30 points) the variables that best discriminated both groups were the successful 2-point field-goals (SC = 0.37). These results allowed understanding that these players' specific characteristics result in a different game-related statistical profile and helped to point out the importance of the perceptive and decision making process in practice and in competition. Key pointsThe players' game-related statistical profile varied according to game type, game outcome and in formative categories in basketball.The results of this work help to point out the different player's performance described in U-16 men's basketball teams compared with senior and professional men's basketball teams.The results obtained enhance the importance of the perceptive and decision making process in practice and in competition.
In this study, we aimed to compare the effects of a single bout of acute moderate and strenuous running exercise on the production of interleukin-17 (IL-17), interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1ra) and inflammatory response of skeletal muscles in regularly trained rats. Eight week old rats were trained by treadmill running 5 days per week for 13 weeks at the durations of 30 min (moderate) and 60 min (strenuous). Two days after the last training session, the animals were subjected to a single bout of moderate or strenuous exercise and serum samples were analyzed for IL-17, IL-6, IL-1ra levels and myeloperoxidase (MPO) activity of gastrocnemius muscle were determined. IL-17 level significantly increased in strenuous exercise group when compared to that of sedentary controls (p < 0.01), On the other hand, only in the moderate exercise group, there was a negative correlation between IL-6 and IL-17 levels (r = - 0.857 and p = 0.014). In conclusion, acute single bout of strenuous exercise increased IL-17 production in trained rats and, this cytokine may be involved in inflammatory process of skeletal muscles. Key pointsA single bout of acute strenuous running exercise markedly elevated IL-17 production.This preliminary result should be supported by forthcoming studies that investigate the role of IL-17 in acute inflammatory process of skeletal muscle.
Sex is a major factor influencing best performances and world records. Here the evolution of the difference between men and women's best performances is characterized through the analysis of 82 quantifiable events since the beginning of the Olympic era. For each event in swimming, athletics, track cycling, weightlifting and speed skating the gender gap is fitted to compare male and female records. It is also studied through the best performance of the top 10 performers in each gender for swimming and athletics. A stabilization of the gender gap in world records is observed after 1983, at a mean difference of 10.0% ± 2.94 between men and women for all events. The gender gap ranges from 5.5% (800-m freestyle, swimming) to 18.8% (long jump). The mean gap is 10.7% for running performances, 17.5% for jumps, 8.9% for swimming races, 7.0% for speed skating and 8.7% in cycling. The top ten performers' analysis reveals a similar gender gap trend with a stabilization in 1982 at 11.7%, despite the large growth in participation of women from eastern and western countries, that coincided with later- published evidence of state-institutionalized or individual doping. These results suggest that women will not run, jump, swim or ride as fast as men. Key pointsSex is a major factor influencing best performances and world records.A stabilization of the gender gap in world records is observed after 1983, at a mean difference of 10.0% ± 2.94 between men and women for all events.The gender gap ranges from 5.5% (800-m freestyle, swimming) to 36.8% (weight lifting).The top ten performers' analysis reveals a similar gender gap trend with a stabilization in 1982 at 11.7%.Results suggest that women will not run, jump, swim or ride as fast as men.
Relative to other team games, the contribution of individual team members to the overall team performance is more easily quantifiable in cricket. Viewing players as securities and the team as a portfolio, cricket thus lends itself better to the use of analytical methods usually employed in the analysis of securities and portfolios. This paper demonstrates the use of stochastic dominance rules, normally used in investment management, to analyze the One Day International (ODI) batting performance of Indian cricketers. The data used span the years 1989 to 2005. In dealing with cricketing data the existence of 'not out' scores poses a problem while processing the data. In this paper, using a Bayesian approach, the 'not-out' scores are first replaced with a conditional average. The conditional average that is used represents an estimate of the score that the player would have gone on to score, if the 'not out' innings had been completed. The data thus treated are then used in the stochastic dominance analysis. To use stochastic dominance rules we need to characterize the 'utility' of a batsman. The first derivative of the utility function, with respect to runs scored, of an ODI batsman can safely be assumed to be positive (more runs scored are preferred to less). However, the second derivative needs not be negative (no diminishing marginal utility for runs scored). This means that we cannot clearly specify whether the value attached to an additional run scored is lesser at higher levels of scores. Because of this, only firstorder stochastic dominance is used to analyze the performance of the players under consideration. While this has its limitation (specifically, we cannot arrive at a complete utility value for each batsman), the approach does well in describing player performance. Moreover, the results have intuitive appeal.
The aims of this study were:
i) to analyze activation patterns of four upper limb muscles (duration of the active and non-active phase) in each lap of 200m breaststroke, ii) quantify neuromuscular fatigue, with kinematics and physiologic assessment. Surface electromyogram was collected for the biceps brachii, deltoid anterior, pectoralis major and triceps brachii of nine male swimmers performing a maximal 200m breaststroke trial. Swimming speed, SL, SR, SI decreased from the 1(st) to the 3(rd) lap. SR increased on the 4(th) lap (35.91 ± 2.99 stroke·min(-1)). Peak blood lactate was 13.02 ± 1.72 mmol·l(-1) three minutes after the maximal trial. The EMG average rectified value (ARV) increased at the end of the race for all selected muscles, but the deltoid anterior and pectoralis major in the 1(st) lap and for biceps brachii, deltoid anterior and triceps brachii in the 4(th) lap. The mean frequency of the power spectral density (MNF) decreased at the 4(th) lap for all muscles. These findings suggest the occurrence of fatigue at the beginning of the 2(nd) lap in the 200m breaststroke trial, characterized by changes in kinematic parameters and selective changes in upper limb muscle action. There was a trend towards a non-linear fatigue state. Key PointsFatigue in the upper limbs occurs in different way as it described by 100m swimming events.Neuromuscular fatigue was estimated by analyzing the physiological changes (high blood lactate concentrations), biomechanical changes in the swimming stroke characteristics (decreased in swimming velocity), and by the changes in the EMG amplitude and frequency parameters at the end of the swimming bout.The amplitude signal of EMG provided by the ARV demonstrated an increase at the end with the respect to the beginning for all muscles under study, excepted for the muscle deltoid anterior.The mean frequency (MNF) in our study decrease at the end of the swimming in the 4(th) lap relative to the 1(st) lap for all muscles under observation, along the 200m breaststroke.
The aim of the present study was to ascertain whether maximal 200 m front crawl swimming strategies and breathing patterns influenced blood gas and acid-base parameters in a manner which gives advantage to former competitive swimmers in comparison with their recreational colleagues. Twelve former competitive male swimmers (the CS group) and nine recreational male swimmers (the RS group) performed a maximal 200 m front crawl swimming with self-selected breathing pattern. Stroke rate (SR) and breathing frequency (BF) were measured during the swimming test. Measures also included blood lactate concentration ([LA]) and parameters of blood acid-base status before and during the first minute after the swimming test. The CS group swam faster then the RS group. Both groups have similar and steady SR throughout the swimming test. This was not matched by similar BF in the CS group but matched it very well in the RS group (r = 0.89). At the beginning of swimming test the CS group had low BF, but they increased it throughout the swimming test. The BF at the RS group remained constant with only mirror variations throughout the swimming test. Such difference in velocity and breathing resulted in maintaining of blood Po 2 from hypoxia and Pco2 from hypercapnia. This was similar in both groups. [LA] increased faster in the CS group than in the RS group. On the contrary, the rate of pH decrease remained similar in both groups. The former competitive swimmers showed three possible advantages in comparison to recreational swimmers during maximal 200 m front crawl swimming: a more dynamic and precise regulation of breathing, more powerful bicarbonate buffering system and better synchronization between breathing needs and breathing response during swimming.
The aims of this investigation were to determine the evolution of selected turn variables during competitive backstroke races and to compare these kinematic variables between two different levels of swimmers. Sixteen national and regional level male swimmers participant in the 200 m backstroke event at the Spanish Swimming Championships in short course (25 m) were selected to analyze their turn performances. The individual distances method with two-dimensional Direct Linear Transformation (2D-DLT) algorithms was used to perform race analyses. National level swimmers presented a shorter "turn time", a longer "distance in", a faster "underwater velocity" and "normalized underwater velocity", and a faster "stroking velocity" than regional level swimmers, whereas no significant differences were detected between levels for the "underwater distance". National level swimmers maintained similar "turn times" over the event and increased "underwater velocity" and "normalized underwater velocity" in the last (seventh) turn segment, whereas regional level swimmers increased "turn time" in the last half of the race. For both national and regional level swimmers, turn "underwater distance" during the last three turns of the race was significantly shorter while no significant differences in distance into the wall occurred throughout the race. The skill level of the swimmers has an impact on the competitive backstroke turn segments. In a 200 m event, the underwater velocity should be maximized to maintain turn proficiency, whereas turn distance must be subordinated to the average velocity.
The purpose of the study was to compare tubing-related injuries to wakeboarding- and water skiing-related injuries. Data was collected from the 2000-2007 National Electronic Injury Surveillance Survey for 1,761 individuals seeking care at an emergency department due to a tubing-, wakeboarding, or water skiing-related injury. Data included patient age and sex, as well as injury characteristics including body region injured (i.e., head and neck, trunk, shoulder and upper extremity, and hip and lower extremity) and diagnosis of injury (e.g., contusion, laceration, or fracture). Case narratives were reviewed to ensure that a tubing-, wakeboarding-, or water skiing-related injury occurred while the individual was being towed behind a boat. Severe injury (defined as an injury resulting in the individual being hospitalized, transferred, held for observation) was compared among the groups using logistic regression. Wakeboard- and tubing-related injuries more commonly involved the head and neck, while water skiing-related injuries were likely to involve the hip and lower extremity. Tubing-related injuries, compared to water skiing-related injuries, were more likely to be severe (OR 2.31, 95% CI 1.23-4.33). Like wakeboarding and water skiing, tubing has inherent risks that must be understood by the participant. While tubing is generally considered a safer alternative to wakeboarding and water skiing, the results of the current study suggest otherwise. Both the number and severity of tubing-related injuries could be prevented through means such as advocating the use of protective wear such as helmets while riding a tube or having recommended safe towing speeds promi-nently placed on inner tubes.
The incidence of injury in combat sports has not been adequately reported although it is important to identify the nature and frequency of injuries prior to the implementation of prevention programs. This study compared injury rates treated in Hospital Emergency Departments between different combat sports of boxing, wrestling, and martial arts. A secondary objective described anatomic region and diagnosis of these injuries. Data were obtained on all boxing, wrestling, and martial arts-related injuries that were in the National Electronic Injury Surveillance System database and resulted in Emergency Department visits between 2002 and 2005. Pearson's chi-square statistics were calculated to compare injury rates for each activity accounting for complex sample design. Martial arts had lower injury rates compared to boxing and wrestling for all diagnoses (p<0.001). Boxing had lower injury rates compared to wrestling for strains/sprains and dislocations. Boxing and wrestling had similar injury rates for concussions. Injury prevention efforts should consider the distribution of injuries and concentrate on preventing strains/sprains in wrestling, concussions in boxing and wrestling, and fractures for all three activities. The findings of the present study do not provide evidence that combat sports have alarmingly high rates of injuries resulting in emergency department visits. Key pointsMartial arts have lower emergency department injury rates compared to boxing and wrestling.Wrestling has higher strains/sprains and dislocation injury rates compared to boxing.Combat sports do not appear to have higher injury rates compared to non-combat sports.
The aims of this paper were to record injury rates among Iranian women competitive Shotokan karate athletes and propose possible predisposing factors. A prospective recording of the injuries resulting from all matches in 6 consecutive women national Shotokan Karate Championships in all age groups in Iran (season 2004-2005) was performed. Data recorded included demographic characteristics (Age and Weight), athletic background (rank, years of experience, time spent training and previous injuries), type, location and reason for the injury, and the result of the match. Results indicate 186 recorded injuries from a total of 1139 bouts involving 1019 athletes, therefore there were 0.163 injury per bout [C.I. 95%: 0.142-0.184] and 183 injuries per 1000 athletes [C.I. 95%: 159-205]. Injuries were most commonly located in the head and neck (55.4%) followed by the lower limb (21%), upper limb (12.9%) and trunk (10.8%). Punches (48. 4%) were associated with more injuries than kicks (33.3%). The injuries consisted of muscle strain and contusion (81, 43.6%), hematoma and epistaxis (49, 26.3%), lacerations and abrasions (28, 15. 1%), concussion (13, 7%), tooth avulsion or subluxation (3, 1.6%), joint dislocation (3, 1.6%) and fractures (3, 1.6%). In conclusion, as the majority of injuries are minor, and severe or longstanding injuries are uncommon, it can be argued that shotokan karate is a relatively safe for females, despite its image as a combat sport, where ostensibly the aim appears to injure your opponent. Further research is needed to evaluate the effective strategies to minimize the risk of injuries. Key points186 injuries were recorded during women competitions.Incidence rates of 0.163 injury per bout and 183 injuries per 1000 athletes were calculated.The injuries were most commonly located in the head and neck.Muscle strain and contusion, hematoma and epistaxis constitute the majority of injuries.
We investigated the change of body composition in ultra- endurance runners during a multi-stage ultra-endurance run, the Isarrun 2006 in Bavaria, Germany, where athletes had to run 338 km within 5 days. Body mass, skin fold thicknesses and circumferences of extremities were measured in 21 well-experienced extreme endurance male runners (mean ± SD, 41.5 ± 6.9 years, 72.6 ± 6.4 kg, 178 ± 5 cm, BMI 23.0 ± 2.0 kg·m(-2)), who finished mainly within the first half of the ranking, in order to calculate skeletal muscle mass and body fat mass to prove changes after the race. Body mass and calculated fat mass did not change significantly (p>0.05), but, calculated skeletal muscle mass decreased significantly (p<0.05) by 0.63 ± 0.79 kg by the end of the race. The most apparent decline (p<0.01) of the calculated skeletal muscle mass was during the first stage, and no changes were observed during the last 4 stages. We conclude, that a multi- stage ultra-endurance run over 338 km within 5 days leads to no changes of body mass or body fat mass, but a statistically significant decrease of skeletal muscle mass of 0.63 ± 0.79 kg by the end of the race in well-trained and well-experienced ultra-endurance runners. The change of skeletal muscle mass has to be evaluated in further studies at ultra-endurance races with suitable methods to detect changes in hydration status and water metabolism. Key pointsUltra-runners at the Isarrun 2006 suffered no loss of body mass.Skeletal muscle mass decreased highly significantly during the first stage but no significant changes of skeletal muscle mass were observed during the following 4 stages of the Isarrun 2006.Body fat mass remained stable during the Isarrun 2006.
The article by Manuel Gómez-López et al., 2010 was read with interest by student members of Cardiff University's newly formed Sports and Exercise Medicine Society. As medical students we, more than most, are aware of the long term effects that a sedentary lifestyle may bring and its impact on a healthcare system such as ours in the United Kingdom (UK).We found the results of the study intriguing, particularly regarding the 'external barriers-lack of time' category as an important factor in not participating in sports. In the UK there is one afternoon every week which is set aside purely for sporting activities, providing the time to train and compete against other universities. Furthermore, UK universities on the whole offer more advanced and diverse facilities than those available to people at school, whilst there is also a greater number of sporting and exercise opportunities for people to partake in. University is potentially one of the best times in life to expand one's horizons and spend time enjoying the various extra-curricular activities that there is on offer, hence it is crucial that any perceived barriers to this are broken down to allow implementation of a healthy routine. Physical activity has been shown to decrease psychosocial stress and cardiovascular mortality (Milani and Lavie, 2009), something that would surely be considered positive if a sedentary individual were contemplating regular exercise.As future doctors we are concerned about an obesity epidemic that is only becoming more severe. Much of adult obesity has its roots in childhood (Sinha and Kling, 2009) and in modern times many children progress to university and further education. With students as the next generation of parents and working people, there should be a clear focus, especially across the developed world, on improving involvement in physical activities in the hope of decreasing prospective morbidity and the strain this brings to each nation's health service.It is undisputed that a lot of time is required to meet educational requirements and academic deadlines, yet it is not immensely difficult for those with an interest in sport to also pursue these activities. Medicine is a demanding and time-consuming course, yet the majority of medical students in our year at Cardiff regularly participate in sports, many of us acquiring important roles within the clubs whilst competing to high standards. We believe that students in the UK who have adopted an inactive way of life may be influenced by intrinsic factors, such as those mentioned within the article, to a greater extent than proposed. It would be easy for people to blame extrinsic factors in this questionnaire to hide their own lack of motivation. Although these intrinsic traits cannot truly be altered, educational institutes should commit to provide the facilities and spare time for sport amongst this age group, therefore partially reducing the hindrance of any external factors. The important observations made by Gómez-López et al. should not be taken for granted; it is crucial that a healthy lifestyle is promoted from an early age to maintain a good level of physical and mental health. Universities have a duty to their students whereby they should remove any barriers preventing students from practicing their chosen activity. In the future we hope that participation levels will continue to rise, bringing with it all the associated benefits.
Heat therapy is commonly used to treat injured muscles, and recently, hyperthermia which has been used in oncology was introduced as a modality for use in sports medicine. The important physiological response which produces most of the beneficial effects of hyperthermia is increased blood flow (Sekins et al., 1984). Effective clinical response occurs when the temperature reaches 41 to 45 °C (Lehmann and de Lateur, 1982), increasing blood flow up to 15 times (Song, 1984). Sekins et al., 1984 reported that to produce observable variations in blood perfusion, temperature must rise above 41.5 °C as fast as possible. While there are several heating modalities, studies have shown that electromagnetic waves are more effective than other thermal modalities for treating injured muscles at depth of 1-4cm (Giombini et al., 2007). However, because of lack of research-based evidence of the microwave hyperthermia treatment, clinical and research studies need to be completed to confirm the therapeutic effectiveness of hyperthermia. We recently reported that hyperthermia treatment with a 434-MHz microwave and direct- contact applicator increased and maintained the muscle temperature locally by 6.3-11.4°C without causing muscle damage (Ichinoseki-Sekine et al., 2007). This system has also been found to be a highly innovative and reliable modality for treating acute muscle injuries (Giombini et al., 2001). However, most of the hyperthermia systems commonly used in clinical situations is equipped with a 2450-MHz microwave generator and a non-contact applicator. The possibility exists that the muscle temperature is influenced by the frequency and applicator style. Thus, the aim of this study was to investigate the changes in human muscle temperature induced by two different types of microwave hyperthermia systems. Our results could assist to solve the lack of research-based evidence for the clinical effectiveness of hyperthermia treatment. In this study two different microwave hyperthermia systems were used. One was a direct- contact microwave hyperthermia device (ALBA Hyperthermia System, Restek SRL, Rome, Italy) equipped with a 434-MHz microwave generator having a curve-shaped microstrip antenna applicator, and a silicon bolus filled with thermostatic water. The skin temperature was automatically controlled by a decrease/increase in the power output to maintain the skin pilot temperature. The microwave power source was set to turn on/off periodically as the default setting, and the temperature data were measured during the power-off phase. The other device was a non-contact microwave device (Microtizer, MT-SDi, Minato Medical Co. Ltd., Osaka, Japan) equipped with a 2450-MHz microwave applicator including a helical antenna. This system does not contain any temperature measurement system, and the skin temperature was maintained manually by reducing the power output or varying the distance between the applicator and skin surface. The settings of both hyperthermia systems were established in accordance with the manufacturers' instructions. The 434-MHz system was set with a power of 60 W, a skin baseline temperature of 40°C, and a bolus water temperature of 38°C. The applicator was placed on the lateral side of one thigh, and the center of the applicator position was adjusted to the position of the thermocouple. The 2450-MHz system was set with a power of 150 W, and the distance between the skin surface and applicator was approximately 15 cm. The skin and muscle temperatures were measured using a digital thermometer (PTW-301, Unique Medical, Tokyo, Japan) every 3 min for 10 s during the power-off phase, and the center of the applicator position was adjusted to the position of the thermocouple.Eleven healthy adult males (24.3 ± 2.2 years, 1.74 ± 0.06 m, 70.0 ± 5.3 kg; mean ± SD) participated in this study. The subjects were placed in the supine position and underwent 30 min of hyperthermia treatment with either the 434 or 2450-MHz system on different days. At least 1 week elapsed between the two measurements. All procedures described in this study were performed with the approval of the Juntendo University Human Ethics Committee and complied with the Declaration of Helsinki. All subjects gave written informed consent. The thermocouple for determining the skin temperature was placed on the belly of the vastus lateralis muscle. After anesthesia with a 60% lidocaine tape (Penles, Wyeth K.K., Tokyo, Japan), a 23-G thermocouple (IT-23, Physitemp Instruments, Clifton, NJ) was inserted into the muscle, and its temperature at a depth of 2.0 ± 0.2 cm was measured. The room temperature and humidity were controlled at 24.5 ± 0.3°C and 51.6 ± 8.9%, respectively. In addition, to determine the depth of the maximum heating point, we evaluated the vertical heating pattern using a muscle equivalent phantom (Okano, et al., 2000). After microwaves were applied, the temperature distribution on the vertical cutting surface of the phantom was recorded immediately using a thermal camera (Thermo Tracer TH71000, NEC San-ei Instruments, Tokyo, Japan).As results, the muscle temperature with the 434-MHz system showed a single peak at approximately 10 min. Significant differences were detected between the systems in peak muscle temperature, temperature rise, and time to peak temperature (p < 0.001; Table 1). The maximum heating point using the 434-MHz system (approximately 2 cm) was deeper than that of the 2450-MHz system (approximately 1 cm). The peak skin temperatures were not significantly different between the two systems.However, the changes in muscle temperature did show different patterns; a single peak at 10 min was seen with the 434-MHz system, whereas a slope was observed with the 2450-MHz system. This behaviour with the 2450-MHz system caused the substantial variation in the time to peak temperature.In general, the therapeutic range for heat treatment in sports medicine is assumed to be from 41 to 45ºC (Lehmann and de Lateur, 1982). When the local muscle temperature first exceeds a threshold of 42 to 45ºC, a rapid perfusion of cooling blood flow is induced in the high-temperature region (Sekins et al., 1982). This thermal washout reduces the temperature to prevent the muscle from overheating. Our results suggest that the 434-MHz system increased the muscle temperature to this therapeutic range and caused thermal washout. However, some subjects could not reach the therapeutic range with the 2450-MHz system, and thermal washout might not have occurred because a large temperature reduction was not observed. We showed that the radiation frequency and applicator type of a microwave hyperthermia system influence the change in human muscle temperature, but not skin temperature. According to the phantom experiment results, the maximum heating point was shallow in the 2450-MHz system; thus, the actual maximum temperature induced by the 2450-MHz system might have been higher by 1ºC than our results. Even so, the muscle temperature in some subjects may not have reached the temperature necessary to cause thermal washout. There are some studies that showed the benefits of hyperthermia at 434-MHz system. Hyperthermia has benefits in acute muscle injuries, chronic overuse tendinopathies and pain reduction (Giombini et al., 2002), with short-term clinical improvement, good safety and no side effects. The important physiological response which produces most of the beneficial effects of hyperthermia is increased blood flow, and the effective clinical response occurs when the temperature reaches 41 to 45ºC. Hyperthermia produces an increase in nutrients and oxygen in the heated region, and both two events are necessary to affect tissue repair. Our result showed that 434-MHz hyperthermia system rapidly increases muscle temperature to above 41ºC, and it support the previous reports. To obtain the effect of hyperthermia treatment efficiently, both time and temperature of application must be controlled. However, to our knowledge, no study measured the changes in human muscle temperature induced by different types of microwave hyperthermia systems. We believe that our results provided research-based evidence for the clinical effectiveness of hyperthermia treatment.
Anterior cruciate ligament (ACL) deficiency increases the risk of early osteoarthritis (OA). Studies of ACL deficient knee kinematics would be important to reveal the disease process and therefore to find mechanisms which would potentially slow OA progression. The purpose of this study was to determine if in vivo kinematics of the anterior cruciate ligament deficient (ACLD) knee during a wide-based squat activity differ from kinematics of the contralateral intact knee. Thirty-three patients with a unilateral ACLD knee consented to participate in this institutional review board approved study with the contralateral intact knee serving as the control. In vivo knee kinematics during the wide-based squat were analyzed using a 2D/3D registration technique utilizing CT-based bone models and lateral fluoroscopy. Comparisons were performed using values between 0 and 100° flexion both in flexion and extension phases of the squat activity. Both the ACLD and intact knees demonstrated increasing tibial internal rotation with knee flexion, and no difference was observed in tibial rotation between the groups. The tibia in the ACLD knee was more anterior than that of the contralateral knees at 0 and 5° flexion in both phases (p < 0.05). Tibiofemoral medial contact points of the ACLD knees were more posterior than that of the contralateral knees at 5, 10 and 15° of knee flexion in the extension phase of the squat activity (p < 0.05). Tibiofemoral lateral contact points of the ACLD knees were more posterior than that of the contralateral knees at 0° flexion in the both phases (p < 0.05). The kinematics of the ACLD and contralateral intact knees were similar during the wide-based squat except at the low flexion angles. Therefore, we conclude the wide-based squat may be recommended for the ACLD knee by avoiding terminal extension.
The purpose of the present study was to analyze longitudinal changes in 3,000 m running performance and the relationship with selected physiological parameters. Eighteen well-trained male middle-distance runners were measured six times (x3 per year) throughout two consecutive competitive seasons. The following parameters were measured on each occasion: maximal oxygen uptake (VO2max), running economy (RE), velocity at maximal oxygen uptake (vVO2max), velocity at 4mmol L-1 blood lactate concentration (V4), and performance velocity (km·h-1) in 3,000 m time trials. Values ranged from 19.59 to 20.16 km·h-1, running performance; 197 to 207 mL·kg-1·km-1. RE; 17.2 to 17.7 km·h-1, V4; 67.1 to 72.5 mL·kg-1·min-1, VO2max; and 19.8 to 20.2 km·h-1, vVO2max. A hierarchical linear model was used to quantify longitudinal relationships between running performance and selected physiological variables. Running performance decreased significantly over time, between each time point the decrease in running velocity was 0.06 km·h-1. The variables that significantly explained performance changes were V4 and vVO2max. Also, vVO2max and V4 were the measures most strongly correlated with performance and can be used to predict 3,000 m race velocity. The best prediction formula for 3,000 m running performance was: y = 0.646 + 0.626x + 0.416z (R2=0.85); where y = V3,000 m velocity (km·h-1), x = V4 (km·h-1) and z = vVO2max (km·h-1). The high predictive power of vVO2max and V4 suggest that both coaches and athletes should give attention to improving these two physiological variables, in order to improve running performance.
Since 1996, women have been competing in the 3000m steeplechase race internationally. Whenever women and men both compete in similar events with different equipment (the barriers are lower for women) consideration should be given as to how techniques should be coached differently. This study investigated the differences in water-jump technique between men and women after accounting for differences in running speed and which techniques led to maintenance of race pace through the water-jump. Eighteen men and 18 women were filmed at two major track and field meets during the 2004 season. Peak Motus 8.2 was used to digitize all seven jumps from each athlete. Various characteristics of water-jump technique were measured or calculated and compared using two multiple linear regressions (one for men and one for women) to determine which characteristics led to maintaining race pace speeds through the water jump obstacle. Repeated measures ANOVA was used to determine any differences between men and women in the measured characteristics of technique.Velocity through the jump divided by race pace was predicted very well by approach velocity and landing distance for men and women. Other characteristics of the movement were non-significant. Differences between genders were found in: approach velocity, take-off distance, landing distance, push-off angle, velocity through jump, and exit velocity. Men and women steeplechasers must focus on approach velocity and landing distance to complete the water-jump close to their race pace. Coaches need to consider many characteristics of technique that differ between men and women.
The low oxidative demand and muscular adaptations accompanying eccentric exercise hold benefits for both healthy and clinical populations. Compression garments have been suggested to reduce muscle damage and maintain muscle function. This study investigated whether compression garments could benefit metabolic recovery from eccentric exercise. Following 30-min of downhill walking participants wore compression garments on one leg (COMP), the other leg was used as an internal, untreated control (CONT). The muscle metabolites phosphomonoester (PME), phosphodiester (PDE), phosphocreatine (PCr), inorganic phosphate (Pi) and adenosine triphosphate (ATP) were evaluated at baseline, 1-h and 48-h after eccentric exercise using 31P-magnetic resonance spectroscopy. Subjective reports of muscle soreness were recorded at all time points. The pressure of the garment against the thigh was assessed at 1-h and 48-h following exercise. There was a significant increase in perceived muscle soreness from baseline in both the control (CONT) and compression (COMP) leg at 1-h and 48-h following eccentric exercise (p < 0.05). Relative to baseline, both CONT and COMP showed reduced pH at 1-h (p < 0.05). There was no difference between CONT and COMP pH at 1-h. COMP legs exhibited significantly (p < 0.05) elevated skeletal muscle PDE 1-h following exercise. There was no significant change in PCr/Pi, Mg2+ or PME at any time point or between CONT and COMP legs. Eccentric exercise causes disruption of pH control in skeletal muscle but does not cause disruption to cellular control of free energy. Compression garments may alter potential indices of the repair processes accompanying structural damage to the skeletal muscle following eccentric exercise allowing a faster cellular repair.
This study investigated the onset of age-related changes in the myocardial antioxidant enzymes and apoptosis and the vulnerability of the myocardium to oxidative stress following exercise training. Few studies have investigated the influence of the most prevalent life-prolonging strategy physical exercise, on the age increment alterations in the myocardial antioxidant enzymes and apoptosis at mid age and to determine whether exercise-induced antioxidant defense system could attenuate lipid peroxidation. Thirty six male Wistar rats were randomly assigned to exercise trained (n = 18) and sedentary (n = 18) groups. The rats in the training group went under 12, 24 and 36 weeks of moderate exercise trainings (25 m·min-1 for 60-min with a 0% slope). Six sedentary controls were killed together with each exercise group at the end of the training programs. Levels of thiobarbituric acid-reactive substances (TBARS) and catalase (CAT) activity in myocardial homogenates were unchanged by training irrespective of the protocol duration. However, an increased content of the TBARS was detected in hearts from both the 24 and 36-week trained and sedentary control rats when compared with their corresponding 12-week groups (p<0.01). The activity of superoxide dismutase (SOD) remained unchanged after the 12-week training period whereas a significant increase was observed in heart homogenates of 24-week trained animals as compared with their sedentary controls (p<0.05). The activity of glutathione peroxidase (GPX) remained unchanged. The rates of apoptosis which was detected by ELISA assays, were significantly modified after 24 and 36-week of training (p<0.05). These results demonstrate that a long-term endurance training (24 weeks) induced increases in SOD activities in rat myocardium and elicited a marked reduction in apoptosis rate. However, a shorter training program (12 weeks) was not effective in increasing heart antioxidant defenses.
Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-ergometer exercise bouts at 85%VO 2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p < 0.001), no significant differences were detected in assessed force variables during the stroke cycle. In contrast, increasing tension induced significantly higher Anterior Deltoid (AD) activity in the latter stages (70 to 90%) of the cycle (p < 0.05). No significant differences were observed across tension levels for Triceps Brachii or Latissimus Dorsi. Kinematic analysis revealed that overhead arm movements accounted for 39 ± 16% of the cycle. Elbow angle at stroke cycle onset was 144 ± 10°; maximal elbow angle (151 ± 7°) occurred at 78 ± 10% into the cycle. All kinematic markers moved to a more anterior position as tension increased. No significant change in wrist marker elevation was observed, while elbow and shoulder marker elevations significantly increased across tension levels (p < 0.05). In conclusion, data suggested that kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil forces.
This study has been performed to reveal hand bone peculiarities of elite male judoists by comparing their phalangeal and metacarpal bones with those of sedentary men on the basis of biometric ratio of the bones by means of three-dimensional (3D) reconstruction of multidetector computed tomography (MDCT) images. For this purpose, the axial images of the right and left hands of 8 elite male judo players (mean age: 22.0 ± 2.9 years, mean weight: 64.0 ± 4.9 kg) and 8 sedentary men (mean age: 26.0 ± 2.8 years, mean weight: 69.0 ± 3.6 kg) were obtained from MDCT. After semi-automatic segmentation and manual editing, the tracings of bone surfaces were stacked and overlaid to be reconstructed as the 3D images by the 3D program. All biometrical measurements of the reconstructed images of the bones were automatically calculated by this program to analyze statistically. This study showed that the differences between biometric ratios of judoist and sedentary men's hand bones were significant contrary to null hypothesis which was established as there is no difference between biometric hand bone ratios of these men of both groups. Therefore null hypothesis was rejected. Author suggests that intense clutching actions practised in judo sports can most probably lead to some hand bone proliferations. 3D reconstructed results belonging to the judo players and sedentary men help orthopaedists to diagnose pathological formations related to hand bones of judoists and may be used for anatomical education in medicine faculties, respectively. We hope that the results from the biometric and reconstructive techniques carried out in this work will contribute to the present knowledge on judoist and shed light on the future studies on sports medicine related to skeletal structure of other sportsmen.
This study examined the variability of physiological, perceptual, stroke and coordination parameters in both genders during several swim trials at the 400-m pace speed. Twelve national level competitors (6 men, 6 women) swam 400-m at maximal speed. They then swam three additional trials (100, 200 and 300-m) at the pace (speed) of the previous 400-m. Three cameras were used to determine stroke cycle [speed (V), stroke length (SL), stroke rate (SR)] and coordination [index of coordination (IdC), stroke phases] parameters. Physiological [heart rate (HR) and lactate [La-] and perceptual [subjective workload (TWL)] parameters were assessed after each swim trial. Inter-trial data indicated that HR, [La-] and TWL increased significantly with the distance swum (p < 0.05). Inter-trial comparison did not show significant variation of stroke cycle and coordination parameters. Inter-lap data were examined within the 400-m and showed that V and SL decreased significantly at the beginning of the trial (p < 0.05), but IdC and SR remained unchanged (p > 0.05). Thus, despite changes in both physiological and perceptual responses consecutive to increasing fatigue, coordination parameters remained stable during an all-out 400-m freestyle swim. The examination of these parameters based on short-distance trials appears then to be valid, which offers interesting perspectives for swim testing. Key points"During a maximal 400-m, fatigue led to an increase in both physiological (heart rate and blood lactate) and perceptual (subjective workload) parameters.The consequence was a decrease in stroke length and therefore in the swimming speed.However, inter-arm coordination did not change during this aerobic task.This indicates that inter-arm coordination can be examined on the basis of short-distance trials rather than on the full distance.
In the frontal crawl, the propulsive action of the limbs causes lateral fluctuations from the straight path, which can be theoretically seen as the best time saving path of the race. The purpose of the present work was to analyze the head trajectory of 10 elite athletes, during a competition of 400 m front crawl, in order to give information regarding the path linearity of elite swimmers. The kinematic analysis of the head trajectories was performed by means of stereo-photogrammetry. Results showed that the forward speed and lateral fluctuations speed are linearly related. Multiple regression analysis of discrete Fourier transformation allowed to distinguish 3 spectral windows identifying 3 specific features: strokes (0.7-5 Hz), breathings (0.4-0.7 Hz), and voluntary adjustments (0-0.4 Hz), which contributed to the energy wasting for 55%, 10%, and 35%, respectively. Both elite swimmers race speed and speed wastage increase while progressing from the 1(st) to the 8(th) length during a 400 m front crawl official competition. The main sources of the lateral fluctuations that lead to the increasing speed wastage could be significantly attributed to strokes and voluntary adjustments, while breathings contribution did not reach statistical significance. In conclusion, both strokes and voluntary adjustments are the main energy consuming events that affect path linearity. Key pointsThe lateral fluctuations (LF) represent indexes of elite performance swimmers during 400 m competitions.The voluntary adjustments needed to go back to the ideal trajectory are more energy consuming than the movements of the swimmer for maintaining the path linearity.The diverge from the ideal swimming trajectory during a high level competition explain about 14.7% of the variations of the average forward velocity during the race.
The placebo effect, a positive outcome resulting from the belief that a beneficial treatment has been received, is widely acknowledged but little understood. It has been suggested that placebo responsiveness, the degree to which an individual will respond to a placebo, might vary in the population. The study aimed to identify placebo-responsive participants from a previously published paper that examined the effects of caffeine and placebos on cycling performance. A quantitative model of placebo responsiveness was defined. 14 male participants were subsequently classified as either placebo responsive or non-responsive. Interviews were conducted to corroborate these classifications. Secondary quantitative analyses of performance data were conducted to identify further placebo responses. Finally, the five factor model of personality was used to explore relationships between personality and placebo responsiveness. Overall, 5 of 14 participants were classified as placebo responsive. Performance data suggested that 2 participants were placebo responsive whilst 12 were not. Interview data corroborated experimental data for these participants and for 9 of the remainder, however it suggested that the remaining 3 had experienced placebo effects. Secondary quantitative analysis revealed that performance for these 3 participants, whilst no better than for non-responsive participants, was associated with substantially increased oxygen uptake in the 2 conditions in which participants believed caffeine had been administered (7.0% ± 15.1; 95% confidence intervals -2.6 to 16.7, and 6.0% ± 15.4; -3.9 to 15.9 respectively). Finally, data suggested that the personality factors of extroversion, agreeableness, openness and neuroticism may relate to placebo responding. Placebo effects such as pain tolerance and fatigue resistance might be experienced by a percentage of participants but might not always be manifest in objective measures of performance.
Multiday ultra-endurance races present athletes with a significant number of physiological and psychological challenges. We examined emotions, the perceived functionality (optimal-dysfunctional) of emotions, strategies to regulate emotions, sleep quality, and energy intakeexpenditure in a four-man team participating in the Race Across AMerica (RAAM); a 4856km continuous cycle race. Cyclists reported experiencing an optimal emotional state for less than 50% of total competition, with emotional states differing significantly between each cyclist over time. Coupled with this emotional disturbance, each cyclist experienced progressively worsening sleep deprivation and daily negative energy balances throughout the RAAM. Cyclists managed less than one hour of continuous sleep per sleep episode, high sleep latency and high percentage moving time. Of note, actual sleep and sleep efficiency were better maintained during longer rest periods, highlighting the importance of a race strategy that seeks to optimise the balance between average cycling velocity and sleep time. Our data suggests that future RAAM cyclists and crew should: 1) identify beliefs on the perceived functionality of emotions in relation to best (functional-optimal) and worst (dysfunctional) performance as the starting point to intervention work; 2) create a plan for support sufficient sleep and recovery; 3) create nutritional strategies that maintain energy intake and thus reduce energy deficits; and 4) prepare for the deleterious effects of sleep deprivation so that they are able to appropriately respond to unexpected stressors and foster functional working interpersonal relationships.
This study investigated if there were acute interference effects of strength exercises on subsequent continuous and intermittent 5Km aerobic exercises. Eleven physically active males (23.1 ± 3.1 yrs, 1.75 ± 0.07 m, 70.5 ± 8.8 kg, and 58.2 ± 8.3 VO2max) performed the following experimental sessions: A) 5 sets of 5 RM on the leg press followed by a 5km run performed continuously (average velocity of the first and second ventilatory thresholds, vΔ50), B) 5 sets of 5 RM on the leg press followed by a 5km run performed intermittently (1 min run at the vVO2max : 1 min of rest); C) 2 sets of 15 RM on the leg press followed by a 5km continuous run; and D) 2 sets of 15 RM on the leg press followed by a 5km intermittent run. Heart rate, blood lactate concentration, rate of perceived exertion, and VO2 at the first and the fifth km were considered for statistical purposes. There were no significant effects of both strength bouts on any of the variables associated with endurance performance (p > 0.05). It seems that both maximum and strength endurance bouts do not acutely impair aerobic performance. Key pointsResidual acute peripheral fatigue does not seem to be the only cause in the interference effect observed during concurrent training regimens.Peripheral fatigue mechanisms of running such as lactate concentration are not altered by prior lower volume strength exercises.Strength and strength endurance exercises performed before a running bout do not seem to impair the performance in the latter.
The primary objective of this study was to assess the efficacy of measuring both aerobic and anaerobic power in a 60-second, maximal effort test. It was hypothesized that oxygen consumption increases rapidly during maximal effort and maximal oxygen consumption (VO2 max) may be reached in one minute. Fifteen United States Cycling Federation competitive cyclists performed the following tests: 1) practice 60-second maximal exertion test; 2) standard incremental workload VO2 max test; 3) Wingate anaerobic power test (WAT); 4) VO2 measured during 60-second maximal exertion test (60-SEC); and 5) VO2 measured during 75-second maximal exertion test (75-SEC). All tests were performed on an electrically-braked cycle ergometer. Hydrostatic weighing was performed to determine percent body fat. Peak oxygen consumption values for the 60-SEC (53.4 ml·kg(-1)·min(-1), 92% VO2 max), and 75-SEC (52.6 ml·kg(-1)·min(-1), 91% VO2 max) tests were significantly lower than VO2 max (58.1 ml·kg(-1)·min(-1)). During the 75-SEC test, there was no significant difference in percentage VO2max from 30 seconds to 75 seconds, demonstrating a plateau effect. There were no significant differences in peak power or relative peak power between the Wingate, 60-SEC, and 75 SEC tests while, as expected, mean power, relative mean power, and fatigue index were significantly different between these tests. Power measures were highly correlated among all three tests. It was concluded that VO2 max was not attained during either the 60-SEC nor 75-SEC tests. Furthermore, high correlations in power output for WAT, 60-SEC, and 75-SEC precludes the necessity for anaerobic tests longer than the 30-second WAT.
The purpose of this study was to determine if Pilates exercise could improve dynamic balance, flexibility, reaction time and muscle strength in order to reduce the number of falls among older women. 60 female volunteers over the age of 65 from a residential home in Ankara participated in this study. Participants joined a 12-week series of 1-hour Pilates sessions three times per week. Dynamic balance, flexibility, reaction time and muscle strength were measured before and after the program. The number of falls before and during the 12-week period was also recorded. Dynamic balance, flexibility, reaction time and muscle strength improved (p < 0. 05) in the exercise group when compared to the non-exercise group. In conclusion, Pilates exercises are effective in improving dynamic balance, flexibility, reaction time, and muscle strength as well as decreasing the propensity to fall in older women. Key pointsPilates-based exercises improve dynamic balance, reaction time and muscle strength in the elderly.Pilates exercise may reduce the number of falls in elderly women by increasing these fitness parameters.
The objective of this study was to compare the kinematic and kinetic differences in snatch performances of elite 69-kg men and women weightlifters, the only category common to both genders. The heaviest lifts performed by 9 men and 9 women weightlifters competing in 69-kg weight class in Group A in the 2010 World Weightlifting Championship were analyzed. The snatch lifts were recorded using 2 cameras (PAL). Points on the barbell and body were manually digitized by using Ariel Performance Analysis System. The results showed that maximal extension angle of the ankle and knee during the first pull, the knee angle at the end of the transition phase, and maximal extension angle of the knee in the second pull were significantly greater in men (p < 0.05). The angular velocity of the hip was significantly greater in men during the first pull (p < 0.05). During the second pull, women showed significantly greater maximal angular velocity at the hip and ankle joints (p < 0.05). Moreover, the maximal vertical linear velocity of the barbell was significantly greater in women (p < 0.05). The absolute mechanical work and power output in the first pull and power output in the second pull were significantly greater in men (p < 0.05). However, the relative mechanical work was significantly greater in women during the second pull (p < 0.05). The results revealed that in 69-kg weight class, women were less efficient than men in the first pull, which is strength oriented, whereas they were as efficient as men in the second pull, which is more power oriented. Key pointsWomen weightlifters should do assistant exercises to strengthen their ankle flexor and knee extensor muscles in order to increase their maximal strength in the first pull.Women weightlifters should be able to execute a deeper and faster knee flexion in the transition phase in order to obtain a greater explosive strength during the second pull.
Previous studies have demonstrated that endurance exercise training increases the level of heat shock proteins (HSPs) in skeletal muscles. However, little attention has been drawn to the effects of high intensity-short duration exercise, or sprint-interval training (SIT) on HSP72 level in rat skeletal muscles. This study performed to test the hypothesis that the SIT would induce the HSP72 in fast and slow skeletal muscles of rats. Young male Wistar rats (8 weeks old) were randomly assigned to a control (CON) or a SIT group (n = 8/group). Animals in the SIT group were trained (1 min/sprint, 6 similar to 10 sets/day and 5 similar to 6 days/week) on a treadmill for 9 weeks. After the training period, HSP72 levels in the plantaris (fast) and soleus (slow) muscles were analyzed by Western blotting method. Enzyme activities (hexokinase, phosphofructokinase and citrate synthase) and histochemical properties (muscle fiber type compositions and cross sectional area) in both muscles were also determined. The SIT resulted in significantly (p < 0.05) higher levels of HSP72 in both the plantaris and soleus muscles compared to the CON group, with the plantaris producing a greater HSP72 increase than the soleus (plantaris; 550 +/- 116%, soleus; 26 +/- 8%, p < 0.05). Further, there were bioenergetic improvements, fast-to-slow shift of muscle fiber composition and hypertrophy in the type IIA fiber only in the plantaris muscle. These findings indicate that the SIT program increases HSP72 level of the rat hindlimb muscles, and the SIT-induced accumulation of HSP72 differs between fast and slow muscles.
This study examined the effectiveness of Ballates training (strengthening of the central core musculature by the inception of balance techniques) compared to more traditional exercise programs, such as step aerobics and walking, on balance in women aged 50- 75 years. Participants were randomly assigned to one of three supervised training groups (1 hour/day, 3 days/week, 13 weeks), Ballates (n = 12), step aerobics (n = 17), or walking (n =15). Balance was measured by four different methods (modified Clinical Test for the Sensory Interaction on Balance - mCTSIB; Unilateral Stance with Eyes Open - US-EO or Eyes Closed - US-EC; Tandem Walk - TW; Step Quick Turn - SQT) using the NeuroCom Balance Master. A 2-way (Group and Trial) repeated measures ANOVA and post-hoc Bonferroni Pair-wise Comparisons were used to evaluate changes in the dependent variables used to describe stability and balance (sway velocity, turn sway, speed, and turn time). Measures of static postural stability and dynamic balance were similar for the three groups prior to training. Following the different exercise interventions, sway velocity on firm and foam surfaces (mCTSIB) with eyes closed (p < 0.05) increased for the Ballates group while the other two exercise groups either maintained or decreased their sway velocity following the training, therefore suggesting that these two groups either maintained or improved their balance. There were significant improvements in speed during the TW test (p < 0.01), and turn time (p < 0.01) and sway (p < 0.05) during the SQT test for each of the three groups. In general, all three training programs improved dynamic balance, however, step aerobics and walking programs resulted in be better improvements in postural stability or static balance when compared to the Ballates program. Key PointsExercise training can improve balanceNeed to consider both static and dynamic aspects of balance individuallyImproved balance can reduce the risk of fall.
The purpose of this study was to compare the VO 2 kinetic and mechanical power responses of boys and men to all out 90 s sprint cycle exercise. Eight boys (14.6 ± 0.3 y) and eight men (33.8 ± 6.5 y) volunteered to participate and completed a ramp test (to determine VO 2peak and ventilatory threshold, VT) and then on subsequent days, two 90 s all out cycle sprints on an isokinetic cycle ergometer. During each test, breath-by-breath pulmonary gas exchange and power output were measured. Parameters from the power output profiles were derived from the average response of the two tests including peak power (PP, highest power output in 1 s), end power (EP 60-90, power over the last 30 s), and mean power over the 90 s (MP 90). Independent pairwise and dependent t-tests were used to compare the data from tests between adults and boys subject groups. Significant differences between adults and boys were found for absolute PP (881.4 ± 60.7 vs 533.6 ± 50.7 W), EP 60-90 (288.6 ± 25.7 vs 134.3 ± 17.6 W) and MP 90 (434.5 ± 27.4 vs 238.4 ±17.3 W, p =0.001) respectively. Relative to body mass significant differences between adults and boys were found for EP 60-90, MP 90 and total work (p < 0.002). The boys attained 90 s VO 2 values that were closer to VO 2peak than their adult counterparts (93.3 ± 2.6 vs 84.9 ± 2.3 %, p = 0.03). They also demonstrated faster VO 2 kinetics (10.8 ± 1.5 vs 17.6 ± 1.0 s, p < 0.01). In conclusion, during all out 90 s cycle sprinting boys were able to attain VO 2 values that were closer to VO 2peak and a faster time constant than adult men. These findings provide insight into the contribution and speed of response of the aerobic system during an 'anaerobic' test.
The purpose was to determine the level of agreement between the Motoriktest für Vier- bis Sechsjährige Kinder [MOT 4-6] and the Movement Assessment Battery for Children [M-ABC]. 48 preschool children participated in the study (Mean age = 5 years, 6 months, SD = 3 months). There was high classification agreement (90%) between both tests. A Kappa correlation coefficient (0.67) provided moderately strong support for convergent validity. Less agreement was shown in identification of motor difficulties (58%). This was reflected by lower correlation coefficients on the fine movement cluster and test item level. The MOT 4-6 showed values within the range of similar movement skill performance assessment protocols. Because of its specific focus it may be of meaningful value to assess movement skill competence in typically developing preschool children (ages 4 to 6). Key pointsThe Motoriktest für Vier- bis Sechsjährige Kinder (MOT 4-6) showed values within the range of similar motor performance tests. Because of its specific focus it may be of great value to assess movement skill competence in typically developing preschool children (ages 4 to 6).Children's movement skill competence can be expressed as a single composite score. The results from this study also support the use of composite scores that include functional categorization (e.g. locomotion, object control and stability).
Prolonged bouts of hyperpnea or resisted breathing are known to result in respiratory muscle fatigue, as are primarily non respiratory exercises such as maximal running and cycling. These exercises have a large ventilatory component, though, and can still be argued to be respiratory activities. Sit-up training has been used to increase respiratory muscle strength, but no studies have been done to determine whether this type of non-respiratory activity can lead to respiratory fatigue. The purpose of the study was to test the effect of sit-ups on various respiratory muscle strength and endurance parameters. Eight subjects performed pulmonary function, maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) measurements, and an incremental breathing test before and after completing a one-time fatiguing exercise bout of sit-ups. Each subject acted as their own control performing the same measurements 3-5 days following the exercise bout, substituting rest for exercise. Following sit-up induced fatigue, significant decreases were measured in MIP [121.6 ± 26 to 113.8 ± 23 cmH2O (P <0.025)], and incremental breathing test duration [9.6 ± 1.5 to 8.5 ± 0.7 minutes (P <0.05)]. No significant decreases were observed from control pre-test to control post-test measurements. We conclude that after a one-time fatiguing sit-up exercise bout there is a reduction in respiratory muscle strength (MIP, MEP) and endurance (incremental breathing test duration) but not spirometric pulmonary function. Key pointsExercise that is primarily abdominal in nature can lead to inspiratory muscle fatigue.This exercise also can cause expiratory muscle fatigue, which would be expected.This study shows a link between a predominantly non-respiratory exercise and decreases in both respiratory muscle strength and endurance.
We studied the effects of self-administered neuromuscular electrical stimulation (NMES) on changes in strength, endurance, selected anthropometric measures, and subject's perceived shape and satisfaction of the abdominal wall. Twenty-four adults (experimental group) stimulated their abdominals 5 days per week (20-40 minutes per session) for 8 weeks and refrained from engaging in any additional exercise during the study. A control group (N=16) refrained from exercising the abdominals or engaging in any other exercise training during the study. Subjects were tested at the beginning, mid-point, and end of the study. Isometric strength of the abdominal muscles was tested using a isokinetic dynamometer, endurance was measured using the ACSM curl-up test, abdominal circumference was measured using a steel tape measure, and body shape and satisfaction were assessed via questionnaire. The stimulation group had a 58% increase in abdominal strength, whereas the control group did not change. The stimulation group also had a 100% increase in abdominal endurance versus a 28% increase in the control group. Waist circumference decreased by of 3.5 cm in the stimulation group compared to no significant change in the control group. All 24 subjects in the stimulation group felt that their midsections were more "toned" and "firmed" and 13/24 (54%) felt that their posture had improved as a result of the stimulation. None of the control group subjects reported changes in these parameters. There were no significant differences in body weight, BMI, or skinfold thickness over the course of the study in either group. NMES, as used in the current study, resulted in significant improvements in the muscular strength and endurance of the abdominal region, as well as subject's perceived shape and satisfaction of the mid-section.
Abdominal bracing is often adopted in fitness and sports conditioning programs. However, there is little information on how muscular activities during the task differ among the muscle groups located in the trunk and from those during other trunk exercises. The present study aimed to quantify muscular activity levels during abdominal bracing with respect to muscle- and exercise-related differences. Ten healthy young adult men performed five static (abdominal bracing, abdominal hollowing, prone, side, and supine plank) and five dynamic (V-sits, curlups, sit-ups, and back extensions on the floor and on a bench) exercises. Surface electromyogram (EMG) activities of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and erector spinae (ES) muscles were recorded in each of the exercises. The EMG data were normalized to those obtained during maximal voluntary contraction of each muscle (% EMGmax). The % EMGmax value during abdominal bracing was significantly higher in IO (60%) than in the other muscles (RA: 18%, EO: 27%, ES: 19%). The % EMGmax values for RA, EO, and ES were significantly lower in the abdominal bracing than in some of the other exercises such as V-sits and sit-ups for RA and EO and back extensions for ES muscle. However, the % EMGmax value for IO during the abdominal bracing was significantly higher than those in most of the other exercises including dynamic ones such as curl-ups and sit-ups. These results suggest that abdominal bracing is one of the most effective techniques for inducing a higher activation in deep abdominal muscles, such as IO muscle, even compared to dynamic exercises involving trunk flexion/extension movements.