Showing papers in "International Journal of Sports Physiology and Performance in 2008"
TL;DR: Variables derived from the CMJ5 may respond differently than their CMJ1 counterparts and should provide insights into differential mechanisms of response and adaptation and the impact of both acute and chronic training and competition.
Abstract: Purpose: To establish the reliability of various measures obtained during single and repeated countermovement jump (CMJ) performance in an elite athlete population. Methods: Two studies, each involving 15 elite Australian Rules Football (ARF) players were conducted where subjects performed two days, separated by one week, of AM and PM trials of either a single (CMJ1) or 5 repeated CMJ (CMJ5). Each trial was conducted on a portable force-plate. The intraday, interday, and overall typical error (TE) and coefficient of variation (CV%) were calculated for numerous variables in each jump type. Results: A number of CMJ1 and CMJ5 variables displayed high intraday, interday, and overall reliability. In the CMJ1 condition, mean force (CV 1.08%) was the most reliable variable. In the CMJ5, flight time and relative mean force displayed the highest repeatability with CV of 1.88% and 1.57% respectively. CMJ1Mean force was the only variable with an overall TE < smallest worthwhile change (SWC). Conclusion: Selected variables obtained during CMJ1 and CMJ5 performance can be used to assess the impact of both acute and chronic training and competition. Variables derived from the CMJ5 may respond differently than their CMJ1 counterparts and should provide insights into differential mechanisms of response and adaptation.
495 citations
TL;DR: Findings support previous findings showing that the session-RPE TL compares favorably with HR-based methods for quantifying internal training load in a variety of soccer training activities.
Abstract: Purpose: The purpose of this study was to compare the session-RPE method for quantifying internal training load (TL) with various HR-based TL quantification methods in a variety of training modes with women soccer players. Methods: Fifteen elite women soccer players took part in the study (age: 19.3 ± 2.0 y and VO2max: 50.8 ± 2.7 mL·kg−1·min−1). Session-RPE, heart rate, and duration were recorded for 735 individual training sessions and matches over a period of 16 wk. Correlation analysis was used to compare session-RPE TLs with three commonly used HR-based methods for assessing TL. Results: The mean correlation for session-RPE TL with Banister’s TRIMP, LTzone TL and Edwards’s TL were (r = 0.84, 0.83, and 0.85, all P < .01, respectively). Correlations for session-RPE TL and three HR-based methods separated by session type were all significant (all P < .05). The strongest correlations were reported for technical (r = 0.68 to 0.82), conditioning (r = 0.60 to 0.79), and speed sessions (r = 0.61 to 0.79). Conclusion: The session-RPE TL showed a significant correlation with all training types common to soccer. Higher correlations were found with less intermittent, aerobic-based training sessions and suggest that HR-based TLs relate better to session-RPE TLs in less intermittent training activities. These results support previous findings showing that the session-RPE TL compares favorably with HR-based methods for quantifying internal TL in a variety of soccer training activities.
278 citations
TL;DR: CMJ1 Flight time appears to be the most useful variable for monitoring neuromuscular status in elite ARF players due to its substantial change compared with 48pre and prematch.
Abstract: Purpose: To examine the acute and short-term responses of variables obtained during a single countermovement jump (CMJ1); repeated countermovement jump involving 5 consecutive efforts without a pause (CMJ5); and cortisol, testosterone, and testos-terone-to-cortisol ratio (T:C) to an elite Australian Rules Football (ARF) match with a view to determining which variables may be most useful for ongoing monitoring. Methods: Twenty-two elite ARF players participating in a preseason cup match performed a CMJ1 and a CMJ5 and provided saliva samples 48 h before the match (48pre), prematch (Pre), postmatch, 24 h post (24post), 72 h post (72post), 96 h post (96post), and 120 h post (120post). The magnitude of change in variables at each time point compared with Pre and 48pre was analyzed using the effect size (ES) statistic. Results: A substantial decrement in the pre- to postmatch comparison occurred in the ratio of CMJ1 Flight time:Contraction time (ES −0.65 ± 0.28). Cortisol (ES 2.34 ± 1.06) and T:C (ES −0.52 ± 0...
203 citations
TL;DR: The session-RPE method provides reasonably accurate assessments of training load compared with HR-based methods, but they deviate in accuracy when proportionally more time is spent training at low or high intensity.
Abstract: Purpose: To establish the relationship between a subjective (session rating of perceived exertion [RPE]) and 2 objective (training impulse [TRIMP]) and summated-heart-rate-zone (SHRZ) methods of quantifying training load and explain characteristics of the variance not accounted for in these relationships. Methods: Thirty-three participants trained ad libitum for 2 wk, and their heart rate (HR) and RPE were recorded to calculate training load. Subjects were divided into groups based on whether the regression equations over- (OVER), under- (UNDER), or accurately predicted (ACCURATE) the relationship between objective and subjective methods. Results: A correlation of r = .76 (95% CI: .56 to .88) occurred between TRIMP and session-RPE training load. OVER spent a greater percentage of training time in zone 4 of SHRZ (ie, 80% to 90% HRmax) than UNDER (46% ± 8% vs 25% ± 10% [mean ± SD], P = .008). UNDER spent a greater percentage of training time in zone 1 of SHRZ (ie, 50% to 60% HRmax) than OVER (15% ± 8% vs 3%...
197 citations
TL;DR: The response of CMJ1Flight time:Contraction time suggests periods of neuromuscular fatigue and change in T:C indicates subjects were unlikely to have been in a catabolic state during the season.
Abstract: Purpose: To examine variations in neuromuscular and hormonal status and their relationship to performance throughout a season of elite Australian Rules Football (ARF). Methods: Fifteen elite ARF players performed a single jump (CMJ1) and 5 repeated countermovement jumps (CMJ5), and provided saliva samples for the analysis of cortisol (C) and testosterone (T) before the season commenced (Pre) and during the 22-match season. Magnitudes of effects were reported with the effect size (ES) statistic. Correlations were performed to analyze relationships between assessment variables and match time, training load, and performance. Results: CMJ1Flight time:Contraction time was substantially reduced on 60% of measurement occasions. Magnitudes of change compared with Pre ranged from 1.0 ± 7.4% (ES 0.04 ± 0.29) to −17.1 ± 21.8% (ES −0.77 ± 0.81). Cortisol was substantially lower (up to −40 ± 14.1%, ES of −2.17 ± 0.56) than Pre in all but one comparison. Testosterone response was varied, whereas T:C increased substanti...
177 citations
TL;DR: In this article, the authors identify the physiological and anthropometric predictors of rhythmic gymnastics performance, which is defined from the total ranking score of each athlete in a national competition.
Abstract: Purpose: To identify the physiological and anthropometric predictors of rhythmic gymnastics performance, which was defined from the total ranking score of each athlete in a national competition. Methods: Thirty-four rhythmic gymnasts were divided into 2 groups, elite (n = 15) and nonelite (n = 19), and they underwent a battery of anthropometric, physical fitness, and physiological measurements. The principal-components analysis extracted 6 components: anthropometric, flexibility, explosive strength, aerobic capacity, body dimensions, and anaerobic metabolism. These were used in a simultaneous multiple-regression procedure to determine which best explain the variance in rhythmic gymnastics performance. Results: Based on the principal-component analysis, the anthropometric component explained 45% of the total variance, flexibility 12.1%, explosive strength 9.2%, aerobic capacity 7.4%, body dimensions 6.8%, and anaerobic metabolism 4.6%. Components of anthropometric (r = .50) and aerobic capacity (r = .49) were significantly correlated with performance ( P < .01). When the multipleregression model—y = 10.708 + (0.0005121 × VO 2 max) + (0.157 × arm span) + (0.814 × midthigh circumference) – (0.293 × body mass)—was applied to elite gymnasts, 92.5% of the variation was explained by VO 2 max (58.9%), arm span (12%), midthigh circumference (13.1%), and body mass (8.5%). Conclusion: Selected anthropometric characteristics, aerobic power, flexibility, and explosive strength are important determinants of successful performance. These findings might have practical implications for both training and talent identification in rhythmic gymnastics.
128 citations
TL;DR: The use of compression garments did not improve or hamper simulated team-sport activity on consecutive days and despite benefits of reduced self-reported muscle soreness during and following exercise each day, no improvements in performance or recovery were apparent.
Abstract: Purpose: The aim of this study was to determine whether compression garments improve intermittent-sprint performance and aid performance or self-reported recovery from high-intensity efforts on consecutive days. Methods: Following familiarization, 14 male rugby players performed two randomized testing conditions (with or without garments) involving consecutive days of a simulated team sport exercise protocol, separated by 24 h of recovery within each condition and 2 weeks between conditions. Each day involved an 80-min high-intensity exercise circuit, with exercise performance determined by repeated 20-m sprints and peak power on a cart dynamometer (single-man scrum machine). Measures of nude mass, heart rate, skin and tympanic temperature, and blood lactate (La−) were recorded throughout each day; also, creatine kinase (CK) and muscle soreness were recorded each day and 48 h following exercise. Results: No differences (P = .20 to 0.40) were present between conditions on either day of the exercise protoco...
111 citations
TL;DR: Cold water immersion did not result in hypothermia and can be considered safe following high intensity cycling in the heat, using the above protocol.
Abstract: Cold water immersion (CWI) has become a popular means of enhancing recovery from various forms of exercise. However, there is minimal scientific information on the physiological effects of CWI following cycling in the heat. Purpose: To examine the safety and acute thermoregulatory, cardiovascular, metabolic, endocrine, and inflammatory responses to CWI following cycling in the heat. Methods: Eleven male endurance trained cyclists completed two simulated ~40-min time trials at 34.3 ± 1.1°C. All subjects completed both a CWI trial (11.5°C for 60 s repeated three times) and a control condition (CONT; passive recovery in 24.2 ± 1.8°C) in a randomized cross-over design. Capillary blood samples were assayed for lactate, glucose, pH, and blood gases. Venous blood samples were assayed for catecholamines, cortisol, testosterone, creatine kinase, C-reactive protein, IL-6, and IGF-1 on 7 of the 11 subjects. Heart rate (HR), rectal (Tre), and skin temperatures (Tsk) were measured throughout recovery. Results: CWI elicited a significantly lower HR (CWI: ∆116 ± 9 bpm vs. CONT: ∆106 ± 4 bpm; P = .02), Tre (CWI: ∆1.99 ± 0.50°C vs. CONT: ∆1.49 ± 0.50°C; P = .01) and Tsk. However, all other measures were not significantly different between conditions. All participants subjectively reported enhanced sensations of recovery following CWI. Conclusion: CWI did not result in hypothermia and can be considered safe following high intensity cycling in the heat, using the above protocol. CWI significantly reduced heart rate and core temperature; however, all other metabolic and endocrine markers were not affected by CWI.
100 citations
TL;DR: The present results demonstrated limited physiological benefits and no performance enhancement through wearing LBCG during a cycling time trial.
Abstract: Purpose: The present investigation examined the physiological and performance effects of lower-body compression garments (LBCG) during a one-hour cycling time-trial in well-trained cyclists. Methods: Twelve well-trained male cyclists ([mean ± SD] age: 20.5 ± 3.6 years; height: 177.5 ± 4.9 cm; body mass: 70.5 ± 7.5 kg; VO2max: 55.2 ± 6.8 mL·kg−1·min−1) volunteered for the study. Each subject completed two randomly ordered stepwise incremental tests and two randomly ordered one-hour time trials (1HTT) wearing either full-length SportSkins Classic LBCG or underwear briefs (control). Blood lactate concentration ([BLa−]), heart rate (HR), oxygen consumption (VO2) and muscle oxygenation (mOxy) were recorded throughout each test. Indicators of cycling endurance performance were anaerobic threshold (AnT) and VO2max values from the incremental test, and mean power (W), peak power (W), and total work (kJ) from the 1HTT Magnitude-based inferences were used to determine if LBCG demonstrated any performance and/or phy...
96 citations
TL;DR: Results suggest that manipulating set-loading configuration can result in a potentiation effect when heavily loaded sets are followed by a lighter set, primarily characterized by an increase in the PV in elite weightlifters.
Abstract: Purpose: To assess the effects of manipulating the loading of successive sets of midthigh clean pulls on the potentiation capabilities of 7 international-level US weightlifters (4 men, 3 women). Methods: Isometric and dynamic peak-force characteristics were measured with a force plate at 500 Hz. Velocity during dynamic pulls was measured using 2 potentiometers that were suspended from the top of the right and left sides of the testing system and attached to both ends of the bar. Five dynamic-performance trials were used (in the following order) as the potentiation protocol: women at 60, 80, 100, 120, and 80 kg and men at 60, 140, 180, 220, and 140 kg. Trials 2 vs 5 were specifically analyzed to assess potentiation capabilities. Isometric midthigh pulls were assessed for peak force and rate of force development. Dynamic lifts were assessed for peak force (PF), peak velocity (PV), peak power (PP), and rate of force development (RFD). Results: Although all values (PF, PV, PP, and RFD) were higher postpotentiation, the only statistically higher value was found for PV (ICCα = .95, P = .011, η 2 = .69). Conclusions: Results suggest that manipulating set-loading configuration can result in a potentiation effect when heavily loaded sets are followed by a lighter set. This potentiation effect was primarily characterized by an increase in the PV in elite weightlifters.
72 citations
TL;DR: It was concluded that 10-m time is a good reflection of acceleration capabilities and either 20 to 40 m in a 40-m sprint test or 20 to 30m in a 30- m sprint test can be used to estimate maximum speed capabilities.
Abstract: Purpose: The purpose of this study was to determine the relationships between split times within sprint tests over 30 m and 40 m in elite Australian Rules footballers. Methods: Data were analyzed from two Australian Football League (AFL) clubs. The first club (n = 35) conducted a 40-m sprint test and recorded split times at 10 m and 20 m. The second club (n = 30) conducted a 30-m sprint test and recorded splits at 10 m and 20 m. Analyses included calculation of Pearson correlations and common variances between all the split times as well as “flying” times (20–40 m for the first club and 20 to 30 m for the second club). Results: There was a high correlation (r = 0.94) between 10-m time and 20-m time within each club, indicating these measures assessed very similar speed qualities. The correlations between 10-m time and times to 30 m and 40 m decreased, but still produced common variances of 79% and 66% respectively. However when the “flying” times (20–40 m and 20–30 m) were correlated to 10-m time, the com...
TL;DR: This commentary aims to raise awareness of issues relating to methodology, physiological responses, and the effectiveness of various ergogenic and training strategies; to promote a greater understanding; and to drive future research.
Abstract: Tests of repeated-sprint ability provide a simple way to evaluate the basic physical characteristics of speed and endurance necessary to excel in various multiple-sprint sports. Furthermore, such tests help overcome the complications associated with field-based evaluations of this type of exercise. Nevertheless, despite over 40 y of research, many issues regarding our understanding of multiple-sprint work remain unresolved. This commentary aims to raise awareness of issues relating to methodology, physiological responses, and the effectiveness of various ergogenic and training strategies; to promote a greater understanding; and to drive future research.
TL;DR: Hydration at summer sports camp is a concern and special efforts need to be made to help youths develop hydration strategies, suggesting other impediments to hydration.
Abstract: Purpose: To assess the hydration status and level of hydration knowledge of youths at summer sports camps. Methods: Sixty-seven active youths, 57 males (mean ± SD, 12 ± 2 y, 136 ± 16 cm, 50.6 ± 21.1 kg) and 10 females (13 ± 2 y, 153 ± 8 cm, 45.2 ± 9.0 kg) participated in 4 d of sports camp. Hydration status was assessed before the first practice (AM) and after the second practice (PM). Participants completed sur veys assessing hydration knowledge (HAQ) and hydration habits on day 3 and a selfassessment (EQ#1). Results: Mean AM urine specific gravity (USG) and urine osmolality (Uosm) scores ranged from minimal to significant dehydration across 4 d, even when temperatures were mild. Correlations between hydration indices and EQ#1, ranging from 0.11 to −0.51, were statistically significant (P < .05), indicating that subjects recognized when they were doing a good or bad job hydrating. HAQ did not correlate strongly with hydration indices suggesting other impediments to hydration. Thirst correlated negatively with EQ#1 (from −0.29 to −0.60). Conclusion: Hydration at summer sports camp is a concern and special efforts need to be made to help youths develop hydration strategies.
TL;DR: A number of physiological variables are correlated with performance in all events and 1000-m, 500-m and 200-m times were predicted with a standard error of only 2.2%, 2.0%, and 1.7%, respectively.
Abstract: Purpose: To determine the relative importance of anthropometric and physiological attributes for performance in the 1000-m, 500-m, and 200-m flatwater kayaking events. Methods: Eighteen competitive male kayakers completed performance trials over the 3 distances and a battery of anthropometric and physiological tests. Results: Performance times (mean ± SD) for 1000 m, 500 m, and 200 m were 262.56 ± 36.44 s, 122.10 ± 5.74 s, and 41.59 ± 2.12 s, respectively. Performance in all 3 events was correlated with a number of physiological parameters; in addition, 500-m and 200-m performance was correlated with upper body dimensions. 1000-m time was predicted by power output at lactate turnpoint expressed as a percentage of maximal aerobic power, work done in a 30-s ergometry test and work done in a 2-min ergometry test (adjusted R 2
TL;DR: It is suggested that coordination training increases the speed with the ball more than typical repeated-sprint training, because this particular action requires improvements in coordination.
Abstract: Young soccer players are usually trained with adult-training methods, even though the physiological adaptations are likely to be very different compared with adults. In contrast, some have suggested training preadolescents only with coordination training. The purpose of this study was to investigate whether coordination or repeated-sprint training better improved speed over 20 m, with and without the ball. Sixteen soccer players (mean age 11 ± 0.5 y) were randomly assigned to a sprint-training group (STG = 7) or a coordination-training group (CTG = 9). The STG trained twice a week for 12 wk and performed 20 repetitions of 20- and 10-m sprints; the CTG performed coordination training (eg, speed ladder running) for the same training duration. Maximal jump height, anthropometric measures, and 20-m sprint time, with and without ball, were evaluated before and after the training period. Statistical significance was determined using two-way ANOVA with repeated measure and Pearson test for correlation. Both grou...
TL;DR: Although strength and conditioning are integral to every American football program, the collaboration with sport scientists has not been as fruitful and only limited studies are available examining the physiological effects of actual competition and physiological adaptations or maladaptations during a season of competition.
Abstract: American football is the most popular sport in the United States. Its popularity is likely related to the intense, fast-paced, physical style of play. The importance of strength and conditioning to success in football has been long understood. In fact, the strength and conditioning profession in North America can take its roots from American football. However, only recently has scientific study confirmed the positive relationships between strength, speed, and power to success in this sport. Although strength and conditioning are integral to every American football program, the collaboration with sport scientists has not been as fruitful. Only limited studies are available examining the physiological effects of actual competition and physiological adaptations or maladaptations during a season of competition. Most studies on American football have primarily focused on physical performance characteristics of these athletes and how various training paradigms can be used to improve performance.
TL;DR: It is concluded that performance was improved possibly based upon a greater reliance on fat metabolism, as indicated by increased FFA and a lower respiratory exchange ratio (RER).
Abstract: Purpose: The purpose of this work was to determine the effects of caffeine on high intensity time trial (TT) cycling performance in well-trained subjects. Subjects: Six male cyclists with the following physical characteristics (mean ± SD) age 30.7 ± 12, height 179.3 ± 7.5 cm, mass 70.0 ± 7.5 kg, VO2max 65.0 ± 6.3 mL·kg−1·min−1 undertook three 1-h TT performances, control (C), placebo (P) and caffeine (CAF), on a Velotron cycle ergometer conducted in a double-blind, random fashion. Subjects rested for 60 min and were then given CAF or P in a dose of 6 mg·kg−1 body mass and then commenced exercise after another 60 min of rest. Before ingestion, 60 min postingestion, and at the end of the TT, finger-prick blood samples were analyzed for lactate. Results: The cyclists rode significantly further in the CAF trial (28.0 ± 1.3 km) than they did in the C (26.3 ± 1.5 km, P .05). Blood lactate levels were ...
TL;DR: The aim of this study was to determine the within- and between-training session reproducibility of two SSG formats (2 versus 2 and 4 versus 4 players) and two regimes (intermittent and continuous).
Abstract: an understanding of the reproducibility of the acute physiological responses and movement demands of these games, when completed within the same session and between different training sessions, is also important This information may allow coaches to better control the SSG training process with soccer players Consequently, the aim of this study was to determine the within- and between-training session reproducibility of two SSG formats (2 versus 2 and 4 versus 4 players) and two regimes (intermittent and continuous)
TL;DR: Findings indicate that resistance training does not surpass standard throwing training in improvement of overarm throwing velocity, and this difference was not statistically significant.
Abstract: Purpose: The main purpose of this study was to compare the effect of a specific resistance training program (throwing movement with a pulley device) with the effect of regular training (throwing with regular balls) on overarm throwing velocity under various conditions. Methods: The training forms were matched for total training load, ie, impulse generated on the ball or pulley device. Both training groups (resistance training n = 7 and regular training n = 6) consisted of women team handball players, and trained 3 times per week for 8 weeks, according to an assigned training program alongside their normal handball training. Results: An increase in throwing velocity with normal balls after the training period was observed for both groups (P = .014), as well as throwing with heavier balls and throwing like actions in the pulley device. Although the regular training group seemed to improve more (6.1%) in throwing velocity with normal balls than the resistance training group (1.4%), this difference was not st...
TL;DR: Five minutes of active recovery during a 15-min interval period is adequate to facilitate blood lactate removal and enhance performance in swimmers.
Abstract: Purpose: To examine the effects of active and passive recovery of various durations after a 100-m swimming test performed at maximal effort. Methods: Eleven competitive swimmers (5 males, 6 females, age: 17.3 ± 0.6 y) completed two 100-m tests with a 15-min interval at a maximum swimming effort under three experimental conditions. The recovery between tests was 15 min passive (PAS), 5 min active, and 10 min passive (5ACT) or 10 min active and 5 min passive (10ACT). Self-selected active recovery started immediately after the first test, corresponding to 60 ± 5% of the 100-m time. Blood samples were taken at rest, 5, 10, and 15 min after the first as well as 5 min after the second 100-m test for blood lactate determination. Heart rate was also recorded during the corresponding periods. Results: Performance time of the first 100 m was not different between conditions (P > .05). The second 100-m test after the 5ACT (64.49 ± 3.85 s) condition was faster than 10ACT (65.49 ± 4.63 s) and PAS (65.89 ± 4.55 s) conditions (P < .05). Blood lactate during the 15-min recovery period between the 100-m efforts was lower in both active recovery conditions compared with passive recovery (P < .05). Heart rate was higher during the 5ACT and 10ACT conditions compared with PAS during the 15-min recovery period (P < .05). Conclusion: Five minutes of active recovery during a 15-min interval period is adequate to facilitate blood lactate removal and enhance performance in swimmers. Passive recovery and/or 10 min of active recovery is not recommended.
TL;DR: Optimal participation and performance of adolescent rugby union players might be compromised by many high-load, high-impact training sessions and games and commitments to other sports and physical activities.
Abstract: Purpose: Investigating adolescent training loads might help us understand optimal training adaptations. GPS tracking devices and training diaries were used to quantify weekly sport and other physical activity demands placed on adolescent rugby union players and profile typical rugby training sessions. Methods: Participants were 75 males age 14 to 18 y who were recruited from rugby teams representing 3 levels of participation: schoolboy, national representative, and a selective sports school talent squad. Results: Schoolboy players covered a distance of (mean ± SD) 3511 ± 836 m, representative-squad players 3576 ± 956 m, and talent-squad players 2208 ± 637 m per rugby training session. The representative squad recorded the highest weekly duration of sport and physical activity (515 ± 222 min/wk), followed by the talent squad (421 ± 211 min/week) and schoolboy group (370 ± 135 min/wk). Profiles of individual players identified as group outliers showed participation in up to 3 games and up to 11 training ses...
TL;DR: Values decreased over the remainder of the ingestion period although still elevated above preingestion levels.
Abstract: This study examined the increase in blood pH and bicarbonate concentration after ingestion of a standard sodium bicarbonate solution. Peak blood pH and bicarbonate concentration occurred between 60 and 90 minutes. Values decreased over the remainder of the ingestion period although still elevated above preingestion levels.
TL;DR: It is concluded that postactivation potentiation may result in a minor increase in the rate of voluntary isometric force production that is unrelated to neural excitability.
Abstract: The contractile history of muscle can potentiate electrically evoked force production. A link to voluntary force production, related in part to an increase in reflex excitability, has been suggested. Purpose: Our purpose was to quantify the effect of postactivation potentiation on voluntary force production and spinal H-reflex excitability during explosive plantar flexion actions. Methods: Plantar flexor twitch torque, soleus H-reflex amplitudes, and the rate of force development of explosive plantar flexion were measured before and after 4 separate conditioning trials (3 × 5 s maximal contractions). Results: Twitch torque and rate of force production during voluntary explosive plantar flexion were significantly increased (P < .05) while H-reflex amplitudes remained unchanged. Although twitch torque was significantly higher after conditioning, leading to a small increase in the rate of voluntary force production, this was unrelated to changes in reflex excitability. Conclusion: We conclude that postactivation potentiation may result in a minor increase in the rate of voluntary isometric force production that is unrelated to neural excitability.
TL;DR: More studies are needed to establish a dose-response relationship to vibration training to provide indications on safe and effective vibration training prescriptions and some guidance on practical applications.
Abstract: The use of vibration as a training intervention has been suggested for more than a decade. Following the initial promising studies, a large number of investigations have been conducted to understand the acute and chronic effects of this novel training modality mainly using special populations, sedentary, physically active, and aged individuals. There is a small number of studies involving athletes. For this reason it is at the moment very difficult to provide safe and effective training guidelines to athletes. We discuss the current findings related to the effectiveness on elite athletes and provide some guidance on practical applications. Vibration is without a doubt an interesting intervention; however, more needs to be done to understand the physiological mechanisms involved in the adaptive responses to vibration exercise. Furthermore, more studies are needed to establish a dose-response relationship to vibration training to provide indications on safe and effective vibration training prescriptions.
TL;DR: It is suggested that there is a counterproductive effect of head and neck cooling garments on water consumption, and changes in body mass suggest an incidence of mild dehydration during wheelchair tennis in the heat.
Abstract: Background: Wheelchair tennis players, competing in hot and humid environments, are faced with an increased risk of heat-related illness and impaired performance. This study examined the effects of head and neck cooling garments on perceptions of exertion (RPE), thermal sensation (TS), and water consumption during wheelchair exercise at 30.4 ± 0.6°C. Methods: Eight highly trained wheelchair tennis players (1 amputee and 7 spinal cord injured) completed two 60-min, intermittent sprint trials; once with cooling (COOL) and once without cooling (CON) in a balanced cross-over design. Players could drink water ad libitum at five predetermined intervals during each trial. Heart rate, blood lactate concentration, peak speed, TS, and RPE were recorded during the trials. Body mass and water consumption were measured before and after each trial. Results: Water consumption was lower in COOL compared with CON (700 ± 393 mL vs. 1198 ± 675 mL respectively; P = 0.042). Trends in data suggested lower RPE and TS under COOL...
TL;DR: The term drafting is mainly used in sports physiology and biomechanics to describe the tactic of performing a mode of activity in a sheltered position to achieve a better final placing than would normally be expected with his or her individual physiological capacities.
Abstract: In many endurance sports, a large part of an athlete's external power is used to overcome drag. This force has 3 components: friction, pressure, and, in swimming, wave drag. When the athlete's velocity is very low, friction drag dominates. In normal sports activities, pressure drag dominates, but frictional drag is influential in the velocity range in which the airstream changes from laminar to turbulent, which on the other hand depends on the roughness of the athlete's clothing. The term drafting is mainly used in sports physiology and biomechanics to describe the tactic of performing a mode of activity in a sheltered position. The growing success and impact of selected endurance sports in which athletes could take advantage of drafting has generated questions on the physiological characteristics and mechanisms regulating human locomotion in sports such as running, 1 cycling, 2 short-track skating, 3 swimming, 4 and triathlon. 5 An athlete who drafts continuously during a race might achieve a better final placing than would normally be expected with his or her individual physiological capacities. For this reason, many athletes attempt to position themselves behind athletes of the same or slightly better ability.
TL;DR: This study characterizes international women's water polo match play as a highly intermittent activity where swimming, particularly high intensity, has greater significance to outside players, whereas wrestling has more significance to center players.
Abstract: Purpose: The purpose of this study was to investigate the physiological demands of field players in international women’s water polo match play. Methods: Video footage was collected at the 13th FINA Women’s Water Polo World Cup in Perth in 2002. Video recordings were analyzed using a simple hand-based notation system to record predefined activity durations, frequencies, and corresponding subjective intensities. Results: Average exercise bout duration was 7.4 ± 2.5 s and exercise to rest ratio within play 1:1.6 ± 0.6. The average pattern of exercise was represented by 64.0 ± 15.3% swimming, 13.1 ± 9.2% contested swimming, 14.0 ± 11.6% wrestling, and 8.9 ± 7.1% holding position. Significant differences existed between outside and center players for percentage time swimming (67.5 ± 14.0% vs 60.2 ± 13.3%, P = .002) and wrestling (9.9 ± 9.3% vs 18.4 ± 11.1%, P = .000). A significant difference was found in the number (P = .017) and duration (P = .010) of high-intensity activity (HIA) bouts performed each quarter for outside (1.8 ± 2.2 bouts, 7.0 ± 3.4 s) and center players (1.2 ± 1.5 bouts, 5.2 ± 3.4 s). Positional differences in HIA were the result of a significant difference (P = .000) in the number of maximal/near maximal swims (outside 1.2 ± 1.5 and center 0.5 ± 0.9 per quarter). Conclusions: This study characterizes international women’s water polo match play as a highly intermittent activity. Swimming, particularly high intensity, has greater significance to outside players, whereas wrestling has greater significance to center players.
TL;DR: It was showed that vibration improved split range of motion over stretching alone, but did not show a difference in pressure-to-pain perception in either the stretched or nonstretched muscles.
Abstract: Serious stretching in many sports involves discomfort and is often an early ceiling on improvements. Purpose: To continue investigation of the use of vibration to enhance acute range of motion while assessing the influence of vibration and stretching on pressure-to-pain threshold perception. Methods: Ten young male gymnasts were assessed for split range of motion. One side split was randomly assigned as the experimental condition, and the other side split was assigned as the control. Both side splits were performed on a vibration device; the experimental condition had the device turned on and the control condition was performed with the device turned off. In addition, the athletes were assessed for pressure-to-pain transition using an algometer on the biceps femoris (stretched muscle) and vastus lateralis (nonstretched muscle) bilaterally. Results: Pre-post difference scores between the vibrated split (most improved) and the nonvibrated split were statistically different (P = .001, 95% confidence inter val of the difference 2.3 to 5.8 cm). Following the stretching protocol, the force values for the pressure-to-pain threshold comparing the vibrated and nonvibrated biceps femoris muscle were not statistically different. The nonstretched vastus lateralis muscle also showed no statistical difference in pressure-to-pain threshold between the vibration and nonvibration conditions. Conclusion: This study showed that vibration improved split range of motion over stretching alone, but did not show a difference in pressure-to-pain perception in either the stretched or nonstretched muscles.
TL;DR: This commentary shows that the proposed method of "magnitude-based" inference is "approximately" Bayesian and rather than assuming no prior information their approach has a very specific, but hidden, joint prior on parameters.
Abstract: In a recent commentary on statistical inference, Batterham and Hopkins advocated an approach to statistical inference centered on expressions of uncertainty in parameters. After criticizing an approach to statistical inference driven by null hypothesis testing, they proposed a method of "magnitude-based" inference and then claimed that this approach is essentially Bayesian but with no prior assumption about the true value of the parameter. In this commentary, after we address the issues raised by Batterham and Hopkins, we show that their method is "approximately" Bayesian and rather than assuming no prior information their approach has a very specific, but hidden, joint prior on parameters. To correctly adopt the type of inference advocated by Batterham and Hopkins, sport scientists need to use fully Bayesian methods of analysis.
TL;DR: The improvement in on-ice skating sprint performance when supplemental training progressed in specificity supports the principle of specificity and promotes transfer to a complex sporting movement such as skating.
Abstract: Purpose: To determine the effectiveness of a progressively “skating specific” periodized off-season training program on skating performance in competitive hockey players. Methods: Twenty (M = 18; F = 2) highly skilled hockey players (age 15.9 ± 1.5 yr) completed 16 wk of standardized resistance and stability training supplemented with either off-ice simulated skating using the SkateSIM (SIM) or plyometric training (PLY) in a crossover design. Group 1 (PLY-SIM; N = 11) completed 8 wk of PLY followed by 8 wk of SIM. Group 2 (SIM-PLY; N = 9) completed 8 wk of SIM followed by 8 wk of PLY. Subjects completed on- and off-ice testing PRE, MID, and POST training. Results: Significant improvements in on-ice 35-m skating sprint (1.0%; P = .009) with significant improvements of 5% to 12% in various off-ice testing measures were observed PRE-MID in both groups. While few off-ice tests improved MID-POST, on-ice 35-m skating sprint times improved MID-POST by 2.3% (P = .000) with greater improvement in PLYSIM (3.5%) versus SIM-PLY (0.8%; P < .002). Off-ice 30-m sprint (r = 0.56; P = .010) and Edgren side shuffle (r = –0.46; P < .040) were the only off-ice tests that significantly correlated to improvements in on-ice skating sprint performance. Conclusion: The initial gains PRE-MID and then the lack of improvement in many off-ice tests from the MID-POST supports the principle of diminishing returns in response to standardized resistance training. The improvement in on-ice skating sprint performance when supplemental training progressed in specificity supports the principle of specificity and promotes transfer to a complex sporting movement such as skating.