Showing papers in "Journal of Strength and Conditioning Research in 2010"
TL;DR: The purpose of this paper is to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and to draw conclusions from the research as toThe optimal protocol for maximizing muscle growth.
Abstract: The quest to increase lean body mass is widely pursued by those who lift weights. Research is lacking, however, as to the best approach for maximizing exercise-induced muscle growth. Bodybuilders generally train with moderate loads and fairly short rest intervals that induce high amounts of metabolic stress. Powerlifters, on the other hand, routinely train with high-intensity loads and lengthy rest periods between sets. Although both groups are known to display impressive muscularity, it is not clear which method is superior for hypertrophic gains. It has been shown that many factors mediate the hypertrophic process and that mechanical tension, muscle damage, and metabolic stress all can play a role in exercise-induced muscle growth. Therefore, the purpose of this paper is twofold: (a) to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and (b) to draw conclusions from the research as to the optimal protocol for maximizing muscle growth.
798 citations
TL;DR: The purpose of this article is to examine kinematics and kinetics of the dynamic squat with respect to the ankle, knee, hip and spinal joints and to provide recommendations based on these biomechanical factors for optimizing exercise performance.
Abstract: The squat is one of the most frequently used exercises in the field of strength and conditioning. Considering the complexity of the exercise and the many variables related to performance, understanding squat biomechanics is of great importance for both achieving optimal muscular development as well as reducing the prospect of a training-related injury. Therefore, the purpose of this article is 2-fold: first, to examine kinematics and kinetics of the dynamic squat with respect to the ankle, knee, hip and spinal joints and, second, to provide recommendations based on these biomechanical factors for optimizing exercise performance.
395 citations
TL;DR: It is demonstrated that high-intensity running is reduced during various periods of elite soccer matches, and high- intensity activity profiles and fatigue patterns are similar between international and elite domestic players but vary markedly between playing positions.
Abstract: The aims of the study were to (a) determine the high-intensity activity patterns of soccer players at different performance levels and playing positions, (b) investigate temporary and end game fatigue in elite domestic and international soccer matches, and (c) quantify acceleration and maximal running speed profiles of elite soccer players. Elite domestic (n = 100) and international (n = 10) soccer players were analyzed using a multicamera computerized tracking system. No differences were found for high-intensity running distance (2,520 +/- 678 vs. 2,745 +/- 332 m), mean recovery time (67 +/- 15 vs. 71 +/- 26 seconds), or maximal running speed (7.76 +/- 0.31 vs. 7.66 +/- 0.34 mxs-1). The distance covered in high-intensity running irrespective of playing level was 18% lower (p < 0.05) in the last than in the first 15-minute period of the game (391 +/- 117 vs. 478 +/- 141 m). The decline in high-intensity running immediately after the most intense 5-minute period was similar between international (222 +/- 33 vs. 109 +/- 37 m or 51% decline) and elite domestic (243 +/- 81 vs. 114 +/- 51 m or 53% decline) players. Wide midfielders, central midfielders, fullbacks, and attackers covered a greater (p < 0.01) distance in high-intensity running than central defenders (3,243 +/- 625, 2,949 +/- 435, 2,806 +/- 408, 2,618 +/- 745 vs. 2,034 +/- 284 m). Results demonstrate that high-intensity running is reduced during various periods of elite soccer matches, and high-intensity activity profiles and fatigue patterns are similar between international and elite domestic players but vary markedly between playing positions. These data provide valuable information to the fitness coach regarding the high-intensity active profile of elite soccer players that could be used to develop soccer-specific training drills.
370 citations
TL;DR: The FMS can be confidently used to assess the movement patterns of athletes and to make decisions related to interventions for performance enhancement, and the FMS may assist in identifying athletes at risk for injury.
Abstract: The Functional Movement Screen (FMS) is a series of 7 tests that categorize fundamental movement. Each test is scored on an ordinal scale with 4 categories. The purpose of this study was to determine the interrater reliability of the FMS. Forty healthy subjects were videotaped while performing the FMS. The videos were independently scored by 4 raters, including 2 experts who instruct FMS training courses and 2 novices who completed a standardized training course on the FMS. Interrater reliability was analyzed using the weighted kappa statistic. The novice raters demonstrated excellent or substantial agreement on 14 of the 17 tests, whereas the expert raters did the same on 13 of the 17 tests. When the novice raters were paired with the expert raters, all 17 components demonstrated excellent or substantial agreement. These data indicate that the FMS can confidently be applied by trained individuals. This would suggest that the FMS can be confidently used to assess the movement patterns of athletes and to make decisions related to interventions for performance enhancement, and the FMS may assist in identifying athletes at risk for injury.
334 citations
TL;DR: The SLJ test is practical, time efficient, and low in cost and equipment requirements and might be considered a general index of muscular fitness in youth.
Abstract: The purpose of the present study was to examine the association among different measures of lower body muscular strength in children, and the association between measures of lower- and upper-body muscular strength. The study population comprises 94 (45 girls) healthy Caucasian children aged 6-17 years. Children performed several lower body explosive muscular strength tests (i.e., standing long jump [SLJ], vertical jump, squat jump, and countermovement jump) and upper body muscular strength tests (i.e., throw basketball, push-ups, and isometric strength exercises). The association among the study tests was analyzed by multiple regression. The SLJ was strongly associated with other lower body muscular strength tests (R = 0.829-0.864), and with upper body muscular strength tests (R = 0.694-0.851). The SLJ test might be therefore considered a general index of muscular fitness in youth. The SLJ test is practical, time efficient, and low in cost and equipment requirements.
293 citations
TL;DR: A review of the literature revealed 29 studies that measured alterations in short-term performance after caffeine ingestion that revealed significant improvements in team sports exercise and power-based sports with caffeine ingestion, yet these effects were more common in elite athletes who do not regularly ingest caffeine.
Abstract: Caffeine is the most widely used drug in the world, commonly ingested in coffee, tea, soda, and energy drinks. Its ability to enhance muscular work has been apparent since the early 1900s. Caffeine typically increases endurance performance; however, efficacy of caffeine ingestion for short-term high-intensity exercise is equivocal, which may be explained by discrepancies in exercise protocols, dosing, and subjects' training status and habitual caffeine intake found across studies. The primary aim of this review is to critically examine studies that have tested caffeine's ability to augment performance during exercise dependent on nonoxidative metabolism such as sprinting, team sports, and resistance training. A review of the literature revealed 29 studies that measured alterations in short-term performance after caffeine ingestion. Each study was critically analyzed using the Physiotherapy Evidence Database (PEDro) scale. The mean PEDro score was 7.76 +/- 0.87. Eleven of 17 studies revealed significant improvements in team sports exercise and power-based sports with caffeine ingestion, yet these effects were more common in elite athletes who do not regularly ingest caffeine. Six of 11 studies revealed significant benefits of caffeine for resistance training. Some studies show decreased performance with caffeine ingestion when repeated bouts are completed. The exact mechanism explaining the ergogenic effect of caffeine for short-term exercise is unknown.
276 citations
TL;DR: It was showed that basketball players experience fatigue as game time progresses and suggests the potential benefit of aerobic and agility conditioning in junior basketball.
Abstract: The aim of this research was to examine the demands of competitive basketball games and to study the relationship between athletes' physical capability and game performance. Physical and physiological game demands and the association of relevant field test with game performance were examined in 18 male junior basketball players. Computerized time-motion analysis, heart rate (HR), and blood-lactate concentration [BL] measurements were performed during 6 basketball games. Players were also measured for explosive power, speed, agility, and maximal-strength and endurance performance. During the games, players covered 7,558 +/- 575 m, of which 1,743 +/- 317; 1,619 +/- 280; and 2,477 +/- 339 m were performed at high, moderate, and low intensities, respectively. The 19.3 +/- 3.5 and 56.0 +/- 6.3% of the playing time was spent above 95% and at 85-95% of maximal HR, respectively. Average and mean peak [BL] were 5.75 +/- 1.25 and 6.22 +/- 1.34 mmolxL, respectively. Distances covered at maximal- and high-speed running significantly (p < 0.01) decreased during the second half. Game maximal- and high-speed running were significantly correlated with endurance performance (r = 0.52, p < 0.05 and r = 0.49, p < 0.05, respectively). High-intensity shuffling distance resulted in being negatively related with agility (r = -0.68, p < 0.05). This study showed that basketball players experience fatigue as game time progresses and suggests the potential benefit of aerobic and agility conditioning in junior basketball.
260 citations
TL;DR: The session-RPE method enabled the detection of periodization patterns in weekly planning in elite professional basketball during the crucial part of the competitive season (1 vs. 2 weekly fixtures model).
Abstract: The aim of this study was to examine the training load (TL) profile of professional elite level basketball players during the crucial parts of the competitive season (pre-play-off finals). Subjects were 8 full-time professional basketball players (age 28 +/- 3.6 years, height 199 +/-7.2 cm, body mass 102 +/- 11.5 kg, and body fat 10.4 +/- 1.5%) whose heart rate (HR) was recorded during each training session and their individual response to TL monitored using the session-rate of perceived exertion (RPE) method (200 training sessions). The association between the session-RPE method and training HR was used to assess the population validity of the session-RPE method. Significant relationships were observed between individual session-RPE and all individual HR-based TL (r values from 0.69 to 0.85; p 0.05). Elite male professional basketball imposes great physiological and psychological stress on players through training sessions and official competitions (1-2 per week). Consequently, the importance of a practical and valid method to assess individual TL is warranted. In this research, we demonstrated that session-RPE may be considered as a viable method to asses TL without the use of more sophisticated tools (i.e., HR monitors). The session-RPE method enabled the detection of periodization patterns in weekly planning in elite professional basketball during the crucial part of the competitive season (1 vs. 2 weekly fixtures model).
256 citations
TL;DR: Because RS and ExpS were equally efficient at enhancing maximal sprinting speed, RS training-induced improvements in RSA were likely more related to progresses in the ability to change direction than ExpS.
Abstract: To compare the effects of explosive strength (ExpS) vs. repeated shuttle sprint (RS) training on repeated sprint ability (RSA) in young elite soccer players, 15 elite male adolescents (14.5 ± 0.5 years) performed, in addition to their soccer training program, RS (n = 7) or ExpS (n = 8) training once a week for a total of 10 weeks. RS training consisted of 2-3 sets of 5-6 × 15- to 20-m repeated shuttle sprints interspersed with 14 seconds of passive or 23 seconds of active recovery (≈2 m·s⁻¹); ExpS training consisted of 4-6 series of 4-6 exercises (e.g., maximal unilateral countermovement jumps (CMJs), calf and squat plyometric jumps, and short sprints). Before and after training, performance was assessed by 10 and 30 m (10 and 30 m) sprint times, best (RSAbest) and mean (RSAmean) times on a repeated shuttle sprint ability test, a CMJ, and a hopping (Hop) test. After training, except for 10 m (p = 0.22), all performances were significantly improved in both groups (all p's < 0.05). Relative changes in 30 m (-2.1 ± 2.0%) were similar for both groups (p = 0.45). RS training induced greater improvement in RSAbest (-2.90 ± 2.1 vs. -0.08 ± 3.3%, p = 0.04) and tended to enhance RSAmean more (-2.61 ± 2.8 vs. -0.75 ± 2.5%, p = 0.10, effect size [ES] = 0.70) than ExpS. In contrast, ExpS tended to induce greater improvements in CMJ (14.8 ± 7.7 vs. 6.8 ± 3.7%, p = 0.02) and Hop height (27.5 ± 19.2 vs. 13.5 ± 13.2%, p = 0.08, ES = 0.9) compared with RS. Improvements in the repeated shuttle sprint test were only observed after RS training, whereas CMJ height was only increased after ExpS. Because RS and ExpS were equally efficient at enhancing maximal sprinting speed, RS training-induced improvements in RSA were likely more related to progresses in the ability to change direction.
249 citations
TL;DR: This analysis has shown that performance improvements can be demonstrated after completion of adequate warm-up activities, and there is little evidence to suggest that warming-up is detrimental to sports participants.
Abstract: The value of warming-up is a worthy research problem because it is not known whether warming-up benefits, harms, or has no effect on individuals. The purpose of this study was to review the evidence relating to performance improvement using a warm-up. A systematic review and meta-analysis were undertaken. Relevant studies were identified by searching Medline, SPORTDiscus, and PubMed (1966-April 2008). Studies investigating the effects of warming-up on performance improvement in physical activities were included. Studies were included only if the subjects were human and only if the warm-up included activities other than stretching. The quality of included studies was assessed independently by 2 assessors using the Physiotherapy Evidence Database scale. Thirty-two studies, all of high quality (6.5-9 [mean = 7.6] of 10) reported sufficient data (quality score >6) on the effects of warming-up on performance improvement. Warm-up was shown to improve performance in 79% of the criterions examined. This analysis has shown that performance improvements can be demonstrated after completion of adequate warm-up activities, and there is little evidence to suggest that warming-up is detrimental to sports participants. Because there were few well-conducted, randomized, controlled trials undertaken, more of these are needed to further determine the role of warming-up in relation to performance improvement.
247 citations
TL;DR: The major practical findings are that subtle changes in SSGs playing rules can influence the physiological, perceptual, and time-motion responses in young elite soccer players and coaches should take care in designing different soccer SSGs as each rule or game format change may influence exercise intensity independently.
Abstract: The aim of this study was to examine acute physiological responses and time-motion characteristics associated with 4 soccer-specific small-sided game (SSG) formats (3 vs. 4 players, 3 vs. 3 players + floater, 5 vs. 6 players, and 5 vs. 5 players + floater) and 4 rule changes in elite youth soccer players. Sixteen male youth soccer players (mean +/- SD: age = 15.6 +/- 0.8 years, stature = 170.8 +/- 6.6 cm, body mass = 67.5 +/- 6.2 kg, and 20-m shuttle run estimated Vo2max = 57.4 +/- 3.7 mlxkgxmin) participated in the study, in which heart rate (HR), rating of perceived exertion (RPE), blood lactate (La), and time-motion characteristics were recorded. The rule change requiring extra sprint running had a greater effect on the time-motion characteristics than all other rule modifications but no effect on acute %HRmax, La, and RPE. Rule changes had no effect on RPE. Fixed underload teams (i.e., lower number of players compared with the opponent team) recorded a significantly higher RPE compared with the fixed overload teams, although there were no differences in %HRmax and La. The major practical findings are that subtle changes in SSGs playing rules can influence the physiological, perceptual, and time-motion responses in young elite soccer players. Rules that are related to a team's chances of scoring may improve player motivation and thereby increase training intensity during SSGs. There were no differences between fixed and variable formats in terms of physiological and perceptual responses, although both may provide useful technical-tactical training. Coaches should take care in designing different soccer SSGs as each rule or game format change may influence exercise intensity independently.
TL;DR: This study suggests that individuals can improve their muscular endurance and flexibility using relatively low-intensity Pilates exercises that do not require equipment or a high degree of skill and are easy to master and use within a personal fitness routine.
Abstract: Many claims have been made about the effectiveness of Pilates exercise on the basic parameters of fitness. The purpose of this study was to determine the effects of Pilates exercise on abdominal endurance, hamstring flexibility, upper-body muscular endurance, posture, and balance. Fifty subjects were recruited to participate in a 12-week Pilates class, which met for 1 hour 2 times per week. Subjects were randomly assigned to either the experimental (n = 25) or control group (n = 25). Subjects performed the essential (basic) mat routine consisting of ~25 separate exercises focusing on muscular endurance and flexibility of the abdomen, low back, and hips each class session. At the end of the 12-week period, a 1-way analysis of covariance showed a significant level of improvement (p <= 0.05) in all variables except posture and balance. This study demonstrated that in active middle-aged men and women, exposure to Pilates exercise for 12 weeks, for two 60-minute sessions per week, was enough to promote statistically significant increases in abdominal endurance, hamstring flexibility, and upper-body muscular endurance. Participants did not demonstrate improvements in either posture or balance when compared with the control group. Exercise-training programs that address physical inactivity concerns and that are accessible and enjoyable to the general public are a desirable commodity for exercise and fitness trainers. This study suggests that individuals can improve their muscular endurance and flexibility using relatively low-intensity Pilates exercises that do not require equipment or a high degree of skill and are easy to master and use within a personal fitness routine.
TL;DR: From the obtained results, it was suggested that the CCT is an adequate training strategy to develop soccer players' muscle power and speed.
Abstract: The purpose of this study was to analyze the short-term effects of complex and contrast training (CCT) on vertical jump (squat and countermovement jump), sprint (5 and 15 m), and agility (505 Agility Test) abilities in soccer players. Twenty-three young elite Portuguese soccer players (age 17.4 +/- 0.6 years) were divided into 2 experimental groups (G1, n = 9, and G2, n = 8) and 1 control group (G3, n = 6). Groups G1 and G2 have done their regular soccer training along with a 6-week strength training program of CCT, with 1 and 2 training sessions.wk, respectively. G3 has been kept to their regular soccer training program. Each training session from the CCT program was organized in 3 stations in which a general exercise, a multiform exercise, and a specific exercise were performed. The load was increased by 5% from 1 repetition maximum each 2 weeks. Obtained results allowed identifying (a) a reduction in sprint times over 5 and 15 m (9.2 and 6.2% for G1 and 7.0 and 3.1%, for G2; p < 0.05) and () an increase on squat and jump (12.6% for G1 and 9.6% for G2; p < 0.05). The results suggested that the CCT induced the performance increase in 5 and 15 m sprint and in squat jump. Vertical jump and sprint performances after CCT program were not influenced by the number of CCT sessions per week (1 or 2 sessions.wk). From the obtained results, it was suggested that the CCT is an adequate training strategy to develop soccer players' muscle power and speed.
TL;DR: In this article, the cross-sectional relationship of strength, power, and performance variables in trained female athletes and determine if the relationship between these variables changes over the course of a season was investigated.
Abstract: The purpose of this study was to investigate (a) the cross-sectional relationship of strength, power, and performance variables in trained female athletes and (b) determine if the relationship between these variables changes over the course of a season. Ten female softball players (age = 18.1 ± 1.6 years, height = 166.5 ± 8.9 cm, and weight = 72.4 ± 10.8 kg) from a state Australian Institute of Sport softball team were tested for maximal lower body strength (one repetition maximum [1RM]), peak force (PF), peak velocity (PV), and peak power (PP) during jump squats unloaded and loaded, unloaded countermovement vertical jump height (VJH) 1 base and 2 base sprint performance and change of direction performance on dominant and nondominant sides. The testing sessions occurred pre, mid, and post a 20-week training period. Relationship between body weight (BW), relative strength (1RM/BW), VJH, relative PP, relative PF, PV, speed, and change of direction variables were assessed by Pearson product-moment correlation coefficient at each testing session. Significant relationships were found across all time points with BW, speed, and change of direction measures (r = 0.70-0.93) and relative strength and measures of speed and change of direction ability (r = -0.73-0.85). There were no significant relationships between VJH and any measure of performance at any time point. In conclusion, BW and relative strength have strong to very strong correlations with speed and change of direction ability, and these correlations remain consistent over the course of the season. However, it seems as if many relationships vary with time, and their relationships should therefore be investigated longitudinally to better determine if these cross-sectional relationships truly reflect a deterministic relationship.
TL;DR: It can be concluded that of the 6 agility tests used in this study, the SBF, TT, and S180° are the most reliable and valid tests for estimating the agility of soccer players.
Abstract: The purpose of this study was to evaluate the reliability and factorial validity of agility tests used in soccer. One hundred fifty (n = 150), elite, male, junior soccer players, members of the First Junior League Team, volunteered to participate in the study. The slalom test (ST) sprint 4 x 5 m (S4 x 5) and sprint 9-3-6-3-6-9 m with 180 degree turns (S180 degrees) tests had a greater reliability coefficient (alpha = 0.992, 0.979, and 0.976), whereas the within-subject variation ranged between 2.9 and 5.6%. The mentioned 6 agility tests resulted in the extraction of 2 significant components. The S4 x 5 test had the lowest correlation coefficient with the first component (r = 0.38), whereas the correlation coefficients of the other 5 agility tests were higher than 0.63. The T-test (TT) showed statistically significant differences between the defenders and midfielders (p < 0.05) and between the defenders and attackers (p < 0.05). Statistical significant differences were determined between the attackers and defenders in the sprint 9-3-6-3-9 m with backward and forward running (SBF) and p < 0.05. It can be concluded that of the 6 agility tests used in this study, the SBF, TT, and S180 degrees are the most reliable and valid tests for estimating the agility of soccer players. According to the results of the study, the TT proved to be the most appropriate for estimating the agility of defenders, the SBF, and S180 degrees for estimating the agility of midfielders, whereas the S4 x 5 test can be used for estimating the agility of attackers.
TL;DR: In conclusion, multiple sets are associated with 40% greater hypertrophy-related ESs than 1 set, in both trained and untrained subjects.
Abstract: Previous meta-analyses have compared the effects of single to multiple sets on strength, but analyses on muscle hypertrophy are lacking. The purpose of this study was to use multilevel meta-regression to compare the effects of single and multiple sets per exercise on muscle hypertrophy. The analysis comprised 55 effect sizes (ESs), nested within 19 treatment groups and 8 studies. Multiple sets were associated with a larger ES than a single set (difference = 0.10 +/- 0.04; confidence interval [CI]: 0.02, 0.19; p = 0.016). In a dose-response model, there was a trend for 2-3 sets per exercise to be associated with a greater ES than 1 set (difference = 0.09 +/- 0.05; CI: -0.02, 0.20; p = 0.09), and a trend for 4-6 sets per exercise to be associated with a greater ES than 1 set (difference = 0.20 +/- 0.11; CI: -0.04, 0.43; p = 0.096). Both of these trends were significant when considering permutation test p values (p < 0.01). There was no significant difference between 2-3 sets per exercise and 4-6 sets per exercise (difference = 0.10 +/- 0.10; CI: -0.09, 0.30; p = 0.29). There was a tendency for increasing ESs for an increasing number of sets (0.24 for 1 set, 0.34 for 2-3 sets, and 0.44 for 4-6 sets). Sensitivity analysis revealed no highly influential studies that affected the magnitude of the observed differences, but one study did slightly influence the level of significance and CI width. No evidence of publication bias was observed. In conclusion, multiple sets are associated with 40% greater hypertrophy-related ESs than 1 set, in both trained and untrained subjects.
TL;DR: The results are important to coaches to prepare players to meet the challenges of international soccer games and show that the ability to perform intense intermittent exercise should be trained regularly in elite female players.
Abstract: The purpose of this study was to compare movement pattern, fatigue development, and heart rate (HR) for top-class elite female players when playing international (INT) vs. domestic league games (DOM). Video-based time-motion analyses and HR recordings were performed on 17 players during INT and DOM. The distances covered in high-intensity running (HIR) and sprinting were longer (p < 0.05) in INT compared with DOM. More (p < 0.05) HIR was covered in INT than DOM during first and second half. Additionally, more (p < 0.05) sprinting occurred in INT compared with DOM in the first half. In both game types, the amount of HIR was reduced by 24-27% (p < 0.05) in the last 15-minute period compared with the first four 15-minute periods of the game. The midfielders covered longer (p < 0.05) distances with HIR in INT than in DOM over the entire game and in the most intense 5-minute period of the games, whereas no differences were observed between the game types for defenders. No difference in the HR response was found between INT and DOM. In conclusion, more HIR and sprinting occur in international compared with domestic games, which may affect the fatigue development for players in physically demanding roles. Thus, our results are important to coaches to prepare players to meet the challenges of international soccer games and show that the ability to perform intense intermittent exercise should be trained regularly in elite female players.
TL;DR: Performing the handgrip strength test with the elbow extended appears the most appropriate protocol to evaluate maximal handg Grip strength in adolescents when using the TKK dynamometer, which appears to provide the highest criterion-related validity and reliability.
Abstract: We examined whether elbow position affects the handgrip strength in adolescents. The criterion-related validity and reliability of the Jamar, DynEx, and TKK dynamometers were also analyzed. A total of 66 adolescents aged 12 to16 years performed the handgrip strength test with the elbow extended and flexed at 90 degrees . The validity and reliability of the Jamar, DynEx, and TKK dynamometers was analysed by using known weights. The highest score was obtained when the test was performed with the elbow in full extension and when using the TKK dynamometer. The criterion-related validity analyses showed a systematic bias of -1.92, -1.43, and 0.49 kg for the Jamar, DynEx, and TKK dynamometers, respectively (all p 0.05). Performing the handgrip strength test with the elbow extended appears the most appropriate protocol to evaluate maximal handgrip strength in adolescents when using the TKK. In addition, the TKK dynamometer appears to provide the highest criterion-related validity and reliability. The present study provides useful and relevant information indicating which elbow position, and which type of dynamometer, yield maximal handgrip strength in adolescents.
TL;DR: It is concluded that biweekly plyometric training of junior soccer players (including adapted hurdle and depth jumps) improved important components of athletic performance relative to standard in-season training.
Abstract: Our hypothesis was that the addition of an 8-week lower limb plyometric training program (hurdle and depth jumping) to normal in-season conditioning would enhance measures of competitive potential (peak power output [PP], jump force, jump height, and lower limb muscle volume) in junior soccer players. The subjects (23 men, age 19 ± 0.7 years, body mass 70.5 ± 4.7 kg, height 1.75 ± 0.06 m, body fat 14.7 ± 2.6%) were randomly assigned to a control (normal training) group (Gc; n = 11) and an experimental group (Gex, n = 12) that also performed biweekly plyometric training. A force-velocity ergometer test determined PP. Characteristics of the squat jump (SJ) and the countermovement jump (CMJ) (jump height, maximal force and velocity before take-off, and average power) were determined by force platform. Video-camera kinematic analyses over a 40-m sprint yielded running velocities for the first step (VS), the first 5 m (V5m) and between 35 and 40 m (Vmax). Leg muscle volume was estimated using a standard anthropometric kit. Gex showed gains relative to controls in PP (p < 0.01); SJ (height p < 0.01; velocity p < 0.001), CMJ (height p < 0.001; velocity p < 0.001, average power p < 0.01) and all sprint velocities (p < 0.001 for V5m and Vmax, p < 0.01 for VS). There was also a significant increase (p < 0.05) in thigh muscle volume, but leg muscle volume and mean thigh cross-sectional area remain unchanged. We conclude that biweekly plyometric training of junior soccer players (including adapted hurdle and depth jumps) improved important components of athletic performance relative to standard in-season training. Accordingly, such exercises are highly recommended as part of an annual soccer training program.
TL;DR: It is apparent that vibration exercise can be effective at eliciting chronic muscle strength adaptations and that gender, training status, and exercise protocol are moderators of the response to vibration exercise for strength development (vertical platforms).
Abstract: The purpose of this meta-analysis was to attempt to gain a clear picture of the magnitude of strength improvements expected after acute and chronic vibration training and to identify specific factors that influence the treatment effects Studies employing a strength training intervention and containing data necessary to calculate effect size (ES) were included in the analysis A total of 31 studies met the inclusion criterion Analysis of ES demonstrated that the type of vibration platform employed is a moderator of the treatment effect of vibration on strength development Differences were noted in both acute and chronic changes in muscle strength when vertical vibration platforms are compared with oscillating platforms Vertical platforms elicit a significantly larger treatment effect for chronic adaptations (ES = 124) compared with oscillating platforms (ES = -013) However, oscillating platforms elicit a greater treatment effect for acute effects (ES = 024) compared with vertical platforms (ES = -007) The data also show that gender, training status, and exercise protocol are moderators of the response to vibration exercise for strength development (vertical platforms) Based on the overall analysis, it is apparent that vibration exercise can be effective at eliciting chronic muscle strength adaptations The vibration exercise can be used by exercise professionals to enhance muscular strength
TL;DR: The study demonstrates that the type of fatigue that occurs after a female soccer game does cause marked impairment in intense intermittent exercise and repeated sprint performance but does not affect vertical jump performance, and support the notion that decrements in distance covered by sprinting and high-speed running toward the end of elite female games are caused by fatigue.
Abstract: The purpose was to examine the fatigue pattern of elite female soccer players after competitive games. Soccer players (n = 23) from the Danish women Premier League performed a countermovement vertical jump test, a repeated 30-m sprint test, and the Yo-Yo intermittent endurance level 2 (Yo-Yo IE2) test at rested state and after a competitive game. Average heart rate during the game was 86 +/- 1% of maximal heart rate with no differences between halves. Blood lactate was 5.1 +/- 0.5 mmol.L after the first half, which was higher (p < 0.05) than after the second half (2.7 +/- 0.4 mmol.L). Yo-Yo IE2 performance was 484 +/- 50 m after the game, which was 62% lower (p < 0.05) than at rested state (1,265 +/- 133 m). Average sprinting time of three 30-m sprints was 5.06 +/- 0.06 seconds after the game, which was 4% slower (p < 0.05) than at rest (4.86 +/- 0.06 seconds). No game-induced effect was observed on vertical jump performance. Significant inverse correlations were observed between Yo-Yo IE2 test performance and fatigue index during the repeated sprint test both at rest (r = -0.76, p < 0.05) and after the game (r = -0.66, p < 0.05). The study demonstrates that the type of fatigue that occurs after a female soccer game does cause marked impairment in intense intermittent exercise and repeated sprint performance but does not affect vertical jump performance. These findings support the notion that decrements in distance covered by sprinting and high-speed running toward the end of elite female games are caused by fatigue.
TL;DR: Differences were particularly evident in intermittent high-intensity endurance and agility performance and Sprint training possibly should be individualized when dealing with positional roles in elite men's basketball.
Abstract: The purpose of the present study was to compare the physical attributes of elite men's basketball players according to age and specific individual positional roles. Forty-five players from 3 national basketball teams (Under-18 years, Under-20 years, and Senior) were measured for anthropometry (height, body mass, percentage body fat), explosive power (5 jumps and vertical jump), speed (5-m, 10-m, and 30-m sprint), agility (T-test), strength (bench press and squat 1 repetition maximum [1RM]), and intermittent high-intensity endurance performance (Yo-Yo intermittent recovery test [Yo-Yo IR1]). Data on match frequency, training routines, and playing experience were also collected. Under-18 players were significantly (p Under-20 > Under-18, p < 0.05). Centers and power forwards were the tallest and the heaviest (p < 0.05). The Yo-Yo IR1 performance was higher (p < 0.01) in point guards than in centers. Point guards showed also better agility and 5- and 10-m performances. Power forwards and centers were stronger than the rest of players' positions in the bench press 1RM (p < 0.01). These results showed the existence of age and positional role differences in fitness performance in men's basketball. Differences were particularly evident in intermittent high-intensity endurance and agility performance. Sprint training possibly should be individualized when dealing with positional roles in elite men's basketball. Strength and conditioning coaches should use Yo-Yo IR1 to assess specific endurance in players of different age and positional role.
TL;DR: The results of this study showed that the Yo-Yo intermittent recovery test (Yo-Yo IR1 and MSFT) may be regarded as valuable tests to assess match fitness and subsequently guide training prescription in youth soccer players.
Abstract: The purpose of this study was to examine the relationship between popular endurance field tests and physical match performance in elite male youth soccer players. Eighteen young male soccer players (age 14.4 ± 0.1 years, height 1.67 ± 4.8 cm, body mass 53.6 ± 1.8 kg) were randomly chosen among a population of elite-level soccer players. Players were observed during international championship games of the corresponding age categories and randomly submitted to the level 1 of the Yo-Yo intermittent recovery test (Yo-Yo IR1), the Multistage Fitness Test (MSFT), and the Hoff test on separate occasions. Physical and physiological match demands were assessed using Global Positioning System technology and short-range telemetry (GPS Elite, Canberra, Australia), respectively. Players covered 6,087 ± 582 m (5,098-7,019 m) of which 15% (930 ± 362 m; 442-1,513) were performed as a high-intensity activity. During the first and second halves, players attained 86.8 ± 6.5 and 85.8 ± 5.8% of maximum heart rate (HRmax; p = 0.17) with peak HRs of 100 ± 2 and 99.4 ± 3.2% of HRmax, respectively. Players' Yo-Yo IR1 and MSFT performance were significantly related (r = 0.62-0.76) to a number of match physical activities. However, the Hoff test was only significantly related with sprint distance (r = 0.70, p = 0.04). The Yo-Yo IR1 showed a very large association with MSFT performance (r = 0.89, p < 0.0001). The results of this study showed that the Yo-Yo IR1 and MSFT may be regarded as valuable tests to assess match fitness and subsequently guide training prescription in youth soccer players. The very strong relationship between Yo-Yo IR1 and MSFT suggests their use according to the period of the season and the aerobic fitness level of the players. Because of the association of the Yo-Yo IR1 and MSFT with match physical performances, these tests should be considered in talent selection and development of players.
TL;DR: HHD was a valid measure of isometric strength at the hip and knee, demonstrating moderate to high correlation values when compared to ID strength measures, and greater strength in these muscles is associated with longer step length and decreased reaction time, which are important components of balance recovery in older adults.
Abstract: Lower-extremity muscle strength is important in predicting fall risk in older adults. Handheld dynamometry (HHD) is a tool used to measure isometric muscle strength in the older adult, but few studies have evaluated the utility of HHD for muscle groups beyond knee extension. The purpose of this study was to evaluate the reliability of HHD at the hip, knee, and ankle and to compare HHD strength values to other isometric dynamometry (ID) and to balance and recovery in older adults. This was a repeated measures study design of 18 men and women, age 65 to 92 years of age, who had HHD strength testing 3 to 7 days apart by the same examiner and repeat testing on the same day using 2 independent examiners. ID strength, balance, step length, and reaction time were measured once. HHD demonstrated good intrarater and interrater reliability for isometric strength at the hip and knee but was not a reliable measure for ankle strength. The HHD was a valid measure of isometric strength at the hip and knee, demonstrating moderate to high correlation values when compared to ID strength measures (r = 0.57-0.86; p < 0.05). Hip and knee strength was positively associated to step length and reaction time but not to balance (r = 0.40-0.71; p < 0.05). In conclusion, HHD is a reliable and valid assessment tool for measuring strength at the hip and knee in older adults, and greater strength in these muscles is associated with longer step length and decreased reaction time, which are important components of balance recovery in older adults. HHD can be used as an effective strength measurement tool for the older adult population.
TL;DR: The results suggest that oxidative stress is markedly upregulated by a soccer game, probably as a part of the exercise-induced inflammatory response, and is accompanied by a marked deterioration of anaerobic performance for as long as 72 hours.
Abstract: Exercise-induced muscle damage is associated with an acute-phase inflammatory response characterized by phagocyte infiltration into muscle and free radical production. Although soccer includes intense eccentric muscle actions that cause muscle damage, the oxidative stress responses after a soccer game are currently unknown. The present investigation attempted to determine the responses of circulating levels of oxidative stress and antioxidant status markers during recovery from a soccer game. Twenty soccer players (experimental group) were assigned to 2 different teams that competed against each other (2 × 45 minutes). Ten other players served as controls (rested). Creatine kinase (CK) activity, uric acid, leukocyte count, malondialdehyde (MDA), protein carbnyls (PC), reduced (GSH) and oxidized glutathione (GSSG), antioxidant capacity (TAC), catalase, glutathione peroxidase activity (GPX), delayed-onset of muscle soreness (DOMS), and anaerobic performance (speed, vertical jump performance) were measured before and following (immediately post, 24 hours, 48 hours, 72 hours) the game. Performance deteriorated (2-17%, p < 0.05) throughout recovery. Leukocytosis developed (p < 0.05) immediately following the game and at 24 hours. Both CK and DOMS (3-8-fold, p < 0.05) increased from baseline and remained elevated (p < 0.05) through 48 hours. Thiobarbituric acid reactive substances (TBARS), PC, uric acid, GPX, and TAC increased (13-67%, p < 0.05) throughout recovery, whereas catalase was elevated (38%, p < 0.05) only immediately after the game. GSH/GSSG declined (17-75%, p < 0.05) throughout recovery. Our results suggest that oxidative stress is markedly upregulated by a soccer game, probably as a part of the exercise-induced inflammatory response, and is accompanied by a marked deterioration of anaerobic performance for as long as 72 hours.
TL;DR: Although game-based training is likely to be useful for improving the skill levels of players, the skill activities used in the present study did not reflect the physiological demands of competition, with players spending more time in low- intensity activities and less time in high-intensity activities than competition.
Abstract: This study investigated the physiological demands of women's field hockey competition and compared these demands to those experienced during game-based training activities. Fourteen elite women field hockey players (mean +/- SD; age, 23.3 +/- 3.2 years; maximal oxygen consumption, 53.5 +/- 4.3 ml x kg(-1) x min(-1)) participated in this study. Global positioning satellite (GPS) system analysis was completed during 19 training appearances and 32 Australian Hockey League (AHL) appearances. All training sessions consisted of game-based activities (i.e., small-sided training games) that were played on a reduced-sized pitch. Movement was recorded by a global positioning satellite unit sampling at 5 Hz. Data were categorized into discreet movement velocity bands, corresponding to low-intensity (0-1 m.s(-1)), moderate-intensity (1-3 m.s(-1) and 3-5 m.s(-1)), and high-intensity (5-7 m.s(-1) and >7 m.s(-1)) activities. Players covered 6.6 km (range: 3.4-9.5 km) over the course of the match. Midfielders spent more time and covered greater distances in high-intensity running (i.e., >5 m.s(-1)) than strikers and defenders. The number of high-velocity and high-acceleration efforts over the course of a match was greater in midfielders. In comparison to competition, game-based training sessions resulted in more time spent in low-intensity (i.e., 0-1 m.s(-1)) activities and less time spent in moderate (i.e., 1-3 m.s(-1) and 3-5 m.s(-1)) and high-intensity (i.e., 5-7 m.s(-1) and >7 m.s(-1)) activities. Although game-based training is likely to be useful for improving the skill levels of players, the skill activities used in the present study did not reflect the physiological demands of competition, with players spending more time in low-intensity activities and less time in high-intensity activities than competition. Modifications in training group size and/or drill design and complexity may better simulate the physiological demands of competition.
TL;DR: Myotest-T is a valid and reliable method for the assessment of vertical jump height, and its use is legitimate for field-based evaluations, whereas Myotest -V is neither valid nor reliable.
Abstract: The aim of the present study was to verify the validity and reliability of the Myotest accelerometric system (Myotest SA, Sion, Switzerland) for the assessment of vertical jump height. Forty-four male basketball players (age range: 9-25 years) performed series of squat, countermovement and repeated jumps during 2 identical test sessions separated by 2-15 days. Flight height was simultaneously quantified with the Myotest system and validated photoelectric cells (Optojump). Two calculation methods were used to estimate the jump height from Myotest recordings: flight time (Myotest-T) and vertical takeoff velocity (Myotest-V). Concurrent validity was investigated comparing Myotest-T and Myotest-V to the criterion method (Optojump), and test-retest reliability was also examined. As regards validity, Myotest-T overestimated jumping height compared to Optojump (p 0.98), that is, excellent validity. Myotest-V overestimated jumping height compared to Optojump (p 12 cm), high limits of agreement ratios (>36%), and low ICCs ( 9 cm). In conclusion, Myotest-T is a valid and reliable method for the assessment of vertical jump height, and its use is legitimate for field-based evaluations, whereas Myotest-V is neither valid nor reliable.
TL;DR: The results of this investigation indicate that performing an acute bout of intense plyometric exercise may induce a short-term muscle damage and marked but transient inflammatory responses, and the need of sufficient recovery between successive plyometricercise training sessions is clearly indicated.
Abstract: The objectives of the present investigation were to study the inflammatory and performance responses after an acute bout of intense plyometric exercise during a prolonged recovery period. Participants were randomly assigned to either an experimental group (P, n = 12) that performed intense plyometric exercises or a control group (C, n = 12) that rested. The delayed onset of muscle soreness (DOMS), knee range of motion (KROM), creatine kinase (CK) and lactate dehydrogenase (LDH) activities, white blood cell count, C reactive protein (CRP), uric acid (UA), cortisol, testosterone, IL-6, IL-1b strength (isometric and isokinetic), and countermovement (CMJ) and static (SJ) jumping performance were measured at rest, immediately postexercise and at 24, 48, 72, 96, and 120 hours of recovery. Lactate was measured at rest and postexercise. Strength remained unchanged throughout recovery, but CMJ and SJ declined (p < 0.05) by 8-20%. P induced a marked rise in DOMS, CK, and LDH (peaked 24-48 hours postexercise) and a KROM decline. An acute-phase inflammatory response consisting of leukocytosis (postexercise and at 24 hours), an IL-6, IL-1b, CRP, and cortisol elevation (during the first 24 hours of recovery) and a delayed increase of UA (peaked at 48 hours) and testosterone (peaked at 72 hours) was observed in P. The results of this investigation indicate that performing an acute bout of intense plyometric exercise may induce a short-term muscle damage and marked but transient inflammatory responses. Jumping performance seems to deteriorate for as long as 72 hours postexercise, whereas strength appears to remain unchanged. The acute-phase inflammatory response after a plyometric exercise protocol appears to follow the same pattern as in other exercise models. These results clearly indicate the need of sufficient recovery between successive plyometric exercise training sessions.
TL;DR: An injury prediction model based on planned and actual training loads was developed and implemented to determine if noncontact, soft-tissue injuries could be predicted and therefore prevented in elite collision sport athletes and provide information on the training dose-response relationship and a scientific method of monitoring and regulating training load in elite collisions sport athletes.
Abstract: Limited information exists on the training dose-response relationship in elite collision sport athletes. In addition, no study has developed an injury prediction model for collision sport athletes. The purpose of this study was to develop an injury prediction model for noncontact, soft-tissue injuries in elite collision sport athletes. Ninety-one professional rugby league players participated in this 4-year prospective study. This study was conducted in 2 phases. Firstly, training load and injury data were prospectively recorded over 2 competitive seasons in elite collision sport athletes. Training load and injury data were modeled using a logistic regression model with a binomial distribution (injury vs. no injury) and logit link function. Secondly, training load and injury data were prospectively recorded over a further 2 competitive seasons in the same cohort of elite collision sport athletes. An injury prediction model based on planned and actual training loads was developed and implemented to determine if noncontact, soft-tissue injuries could be predicted and therefore prevented in elite collision sport athletes. Players were 50-80% likely to sustain a preseason injury within the training load range of 3,000-5,000 units. These training load 'thresholds' were considerably reduced (1,700-3,000 units) in the late-competition phase of the season. A total of 159 noncontact, soft-tissue injuries were sustained over the latter 2 seasons. The percentage of true positive predictions was 62.3% (n = 121), whereas the total number of false positive and false negative predictions was 20 and 18, respectively. Players that exceeded the training load threshold were 70 times more likely to test positive for noncontact, soft-tissue injury, whereas players that did not exceed the training load threshold were injured 1/10 as often. These findings provide information on the training dose-response relationship and a scientific method of monitoring and regulating training load in elite collision sport athletes.
TL;DR: The physiologic impact of specific IS is substantially higher than in traditional IL and can aid coaches in the design of intermittent training programs using classical (IL) or a specific form (IS) of running to induce different physiologic responses.
Abstract: The aim of the present study was to compare the physiologic impact of intermittent exercise in specific shuttle running (IS), which requires 180° directional changes, and traditional in-line (IL) running. Ten elite male adult soccer players performed different intermittent exercises according to their maximal aerobic velocity (νOO2max): 30-30 seconds at 100% (30 s of runs at 100% of νOO2max alternated with 30-s recovery period), 105%, and 110% of νOO2max with active recovery, 15-15 seconds at 105%, 110%, and 115% of νOO2max, and 10-10 seconds at 110%, 115%, and 120% of νOO2max with passive recovery. Each exercise was performed in the IL and IS format in a randomized order. Heart rate (HR) expressed in percentage of HR reserve (HRres), postexercise blood lactate concentration [La], and ratings of perceived exertion (RPE) were recorded. The different 30-30 seconds showed significantly higher HRres responses in IS compared with IL (p < 0.01). The [La] and RPE results indicated higher values in IS. In conclusion, the physiologic impact of specific IS is substantially higher than in traditional IL. The changes of direction induce an increase in the anaerobic metabolism solicitation and consequently create different responses compared with traditional IL running. This information can aid coaches in the design of intermittent training programs using classical (IL) or a specific form (IS) of running to induce different physiologic responses.