Showing papers in "International Journal of Sports Physiology and Performance in 2015"
TL;DR: The authors provide the 1st report of seasonal training load in elite soccer players and observed that periodization of training load was typically confined toMD-1 (regardless of mesocycle), whereas no differences were apparent during MD-2 to MD-5, although no difference was apparent between these latter time points.
Abstract: Purpose: To quantify the seasonal training load completed by professional soccer players of the English Premier League. Methods: Thirty players were sampled (using GPS, heart rate, and rating of perceived exertion [RPE]) during the daily training sessions of the 2011–12 preseason and in-season period. Preseason data were analyzed across 6 × 1-wk microcycles. In-season data were analyzed across 6 × 6-wk mesocycle blocks and 3 × 1-wk microcycles at start, midpoint, and end-time points. Data were also analyzed with respect to number of days before a match. Results: Typical daily training load (ie, total distance, high-speed distance, percent maximal heart rate [%HRmax], RPE load) did not differ during each week of the preseason phase. However, daily total distance covered was 1304 (95% CI 434–2174) m greater in the 1st mesocycle than in the 6th. %HRmax values were also greater (3.3%, 1.3–5.4%) in the 3rd mesocycle than in the first. Furthermore, training load was lower on the day before match (MD-1) than 2 (MD-2) to 5 (MD-5) d before a match, although no difference was apparent between these latter time points. Conclusions: The authors provide the 1st report of seasonal training load in elite soccer players and observed that periodization of training load was typically confined to MD-1 (regardless of mesocycle), whereas no differences were apparent during MD-2 to MD-5. Future studies should evaluate whether this loading and periodization are facilitative of optimal training adaptations and match-day performance.
287 citations
TL;DR: The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection, but the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used.
Abstract: Purpose To examine the reliability and magnitude of change after fatiguing exercise in the countermovement-jump (CMJ) test and determine its suitability for the assessment of fatigue-induced changes in neuromuscular (NM) function. A secondary aim was to examine the usefulness of a set of alternative CMJ variables (CMJ-ALT) related to CMJ mechanics. Methods Eleven male college-level team-sport athletes performed 6 CMJ trials on 6 occasions. A total of 22 variables, 16 typical (CMJ-TYP) and 6 CMJ-ALT, were examined. CMJ reproducibility (coefficient of variation; CV) was examined on participants' first 3 visits. The next 3 visits (at 0, 24, and 72 h postexercise) followed a fatiguing high-intensity intermittent-exercise running protocol. Meaningful differences in CMJ performance were examined through effect sizes (ES) and comparisons to interday CV. Results Most CMJ variables exhibited intraday (n = 20) and interday (n = 21) CVs of Conclusions The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection. However, the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used.
247 citations
TL;DR: Perceived ratings of fatigue and Ln rMSSD were sensitive to daily fluctuations in THIR distance in a sample of elite soccer players and show promise as simple, noninvasive assessments of fatigue status in elite football players during a short in-season competitive phase.
Abstract: Purpose: To quantify the relationship between daily training load and a range of potential measures of fatigue in elite soccer players during an in-season competitive phase (17 d). Methods: Total high-intensity-running (THIR) distance, perceived ratings of wellness (fatigue, muscle soreness, sleep quality), countermovement-jump height (CMJ), postexercise heart-rate recovery (HRR), and heart-rate variability (Ln rMSSD) were analyzed during an in-season competitive period (17 d). General linear models were used to evaluate the influence of daily fluctuation in THIR distance on potential fatigue variables. Results: Fluctuations in fatigue (r = −.51, large, P < .001), Ln rMSSD (r = −.24, small, P = .04), and CMJ (r = .23, small, P = .04) were significantly correlated with fluctuations in THIR distance. Correlations between variability in muscle soreness, sleep quality, and HRR and THIR distance were negligible and not statistically significant. Conclusions: Perceived ratings of fatigue and Ln rMSSD were sensi...
192 citations
TL;DR: The eccentric-based program led to a reduction in muscle-injury incidence and severity and showed improvements in common soccer tasks such as jumping ability and linear-sprinting speed.
Abstract: Purpose: To analyze the effect of an eccentric-overload training program (ie, half-squat and leg-curl exercises using flywheel ergometers) with individualized load on muscle-injury incidence and severity and performance in junior elite soccer players. Methods: Thirty-six young players (U-17 to U-19) were recruited and assigned to an experimental (EXP) or control group (CON). The training program consisted of 1 or 2 sessions/wk (3–6 sets with 6 repetitions) during 10 wk. The outcome measured included muscle injury (incidence per 1000 h of exposure and injury severity) and performance tests (countermovement jump [CMJ], 10-m and 20-m sprint test). Results: Between-groups results showed a likely (ES: 0.94) lower number of days of absence per injury and a possible decrement of incidence per 1000 h of match play in EXP than in CON. Regarding muscle performance, a substantial better improvement (likely to very likely) was found in 20-m sprint time (ES: 0.37), 10-m flying-sprint time (ES: 0.77), and CMJ (ES: 0.79...
170 citations
TL;DR: The aim of this commentary is to provide a detailed insight into the complexity of match running performance and the most influential factors.
Abstract: Time-motion analysis is a valuable data-collection technique used to quantify the match running performance of elite soccer players. However, interpreting the reductions in running performance in the second half or temporarily after the most intense period of games is highly complex, as it could be attributed to physical or mental fatigue, pacing strategies, contextual factors or a combination of mutually inclusive factors. Given that research in this domain typically uses a reductionist approach whereby match-running performance is examined in isolation without integrating other factors this ultimately leads to a 1-dimensional insight into match performance. Subsequently, a cohesive review of influencing factors does not yet exist. The aim of this commentary is to provide a detailed insight into the complexity of match running performance and the most influential factors.
159 citations
TL;DR: Examining the factors that compromise sleep during a season and after competition and discusses strategies that may help improve sleep in team-sport athletes finds naps, sleep extension, and sleep-hygiene practices appear advantageous to performance.
Abstract: While the effects of sleep loss on performance have previously been reviewed, the effects of disturbed sleep on recovery after exercise are less reported. Specifically, the interaction between sleep and physiological and psychological recovery in team-sport athletes is not well understood. Accordingly, the aim of the current review was to examine the current evidence on the potential role sleep may play in postexercise recovery, with a tailored focus on professional team-sport athletes. Recent studies show that team-sport athletes are at high risk of poor sleep during and after competition. Although limited published data are available, these athletes also appear particularly susceptible to reductions in both sleep quality and sleep duration after night competition and periods of heavy training. However, studies examining the relationship between sleep and recovery in such situations are lacking. Indeed, further observational sleep studies in team-sport athletes are required to confirm these concerns. Naps, sleep extension, and sleep-hygiene practices appear advantageous to performance; however, future proof-of-concept studies are now required to determine the efficacy of these interventions on postexercise recovery. Moreover, more research is required to understand how sleep interacts with numerous recovery responses in team-sport environments. This is pertinent given the regularity with which these teams encounter challenging scenarios during the course of a season. Therefore, this review examines the factors that compromise sleep during a season and after competition and discusses strategies that may help improve sleep in team-sport athletes.
150 citations
TL;DR: The external-load measures found to be moderately predictive of RPE-TL in soccer training were HSR distance and the number of impacts and accelerations, which provide new evidence to support the use of R PE-TL as a global measure of training load in elite soccer.
Abstract: Purpose: The aim of the current study was to identify the external-training-load markers that are most influential on session rating of perceived exertion (RPE) of training load (RPE-TL) during elite soccer training. Methods: Twenty-two elite players competing in the English Premier League were monitored. Training-load data (RPE and 10-Hz GPS integrated with a 100-Hz accelerometer) were collected during 1892 individual training sessions over an entire in-season competitive period. Expert knowledge and a collinearity r 14.4 km/h) distance and number of impacts and accelerations >3 m/s2 remained in the final multivariate model (P < .001). The adjusted correlations with RPE were r = .14, ...
125 citations
TL;DR: The isometric midthigh pull (IMTP) has been used to monitor changes in force, maximum rate of force development (mRFD), and impulse, with performance in this task being associated withperformance in athletic tasks.
Abstract: The isometric midthigh pull (IMTP) has been used to monitor changes in force, maximum rate of force development (mRFD), and impulse, with performance in this task being associated with performance in athletic tasks. Numerous postures have been adopted in the literature, which may affect the kinetic variables during the task; therefore, the aim of this investigation was to determine whether different knee-joint angles (120°, 130°, 140°, and 150°) and hip-joint angles (125° and 145°), including the subjects preferred posture, affect force, mRFD, and impulse during the IMTP. Intraclass correlation coefficients demonstrated high within-session reliability (r ≥ .870, P .819, P .05, Cohen d = 0.037, power = .408), mRFD (P > .05, Cohen d = 0.037, power = .409), or impulse at 100 ms (P > .05, Cohen d = 0.056, power = .609), 200 ms (P > .05, Cohen d = 0.057, power = .624), or 300 ms (P > .05, Cohen d = 0.061, power = .656) across postures. Smallest detectable differences demonstrated that changes in performance of >1.3% in peak isometric force, >10.3% in mRFD, >5.3% in impulse at 100 ms, >4.4% in impulse at 200 ms, and >7.1% in impulse at 300 ms should be considered meaningful, irrespective of posture.
111 citations
TL;DR: Age and playing position affect the absolute and relative intensity of speed-related actions during matches, and regardless of age and playing positions, faster players were likely to reach higher PMSAbs and possibly lower PMSRel.
Abstract: This study assessed the relationship between peak match speed (PMS) and maximal sprinting speed (MSS) in regard to age and playing positions. MSS and absolute PMS (PMSAbs) were collected from 180 male youth soccer players (U13–U17, 15.0 ± 1.2 y, 161.5 ± 9.2 cm, and 48.3 ± 8.7 kg). The fastest 10-m split over a 40-m sprint was used to determine MSS. PMSAbs was recorded using a global positioning system and was also expressed as a percentage of MSS (PMSRel). Sprint data were compared between age groups and between playing positions. Results showed that regardless of age and playing positions, faster players were likely to reach higher PMSAbs and possibly lower PMSRel. Despite a lower PMSAbs than in older groups (eg, 23.4 ± 1.8 vs 26.8 ± 1.9 km/h for U13 and U17, respectively, ES = 1.9 90%, confidence limits [1.6;2.1]), younger players reached a greater PMSRel (92.0% ± 6.3% vs. 87.2% ± 5.7% for U13 and U17, respectively, ES = –0.8 90% CL [–1.0;–0.5]). Playing position also affected PMSAbs and PMSRel, as stri...
92 citations
TL;DR: In this elite sample, rugby union athletes typically displayed greater short-distance sprint performance, which may be linked to an ability to generate high levels of horizontal force and power.
Abstract: Purpose: To compare mechanical properties of overground sprint running in elite rugby union and rugby league athletes. Methods: Thirty elite rugby code (15 rugby union and 15 rugby league) athletes participated in this cross-sectional analysis. Radar was used to measure maximal overground sprint performance over 20 or 30 m (forwards and backs, respectively). In addition to time at 2, 5, 10, 20, and 30 m, velocity-time signals were analyzed to derive external horizontal force–velocity relationships with a recently validated method. From this relationship, the maximal theoretical velocity, external relative and absolute horizontal force, horizontal power, and optimal horizontal force for peak power production were determined. Results: While differences in maximal velocity were unclear between codes, rugby union backs produced moderately faster split times, with the most substantial differences occurring at 2 and 5 m (ES 0.95 and 0.86, respectively). In addition, rugby union backs produced moderately larger ...
90 citations
TL;DR: When assessing large groups it appears that only 1 trial is required when assessing the RSI variable from the 20, 40, and 50-cm drop heights.
Abstract: Purpose: To evaluate the reliability of the Reactive Strength Index (RSI) and jump-height (JH) performance from multiple drop heights in an elite population. Methods: Thirteen professional basketball players (mean ±SD age 25.8 ± 3.5 y, height 1.96 ± 0.07 m, mass 94.8 ± 8.2 kg) completed 3 maximal drop-jump attempts onto a jump mat at 4 randomly assigned box heights and 3 countermovement-jump trials. Results: No statistical difference was observed between 3 trials for both the RSI and JH variable at all the tested drop heights. The RSI for drop-jump heights from 20 cm resulted in a coefficient of variation (CV) = 3.1% and an intraclass correlation (ICC α) = .96, 40 cm resulted in a CV = 3.0% and an ICC α = .95, and 50 cm resulted in a CV = 2.1% and an ICC α = .99. The JH variable at the 40-cm drop-jump height resulted in the highest reliability CV = 2.8% and an ICC α = .98. Conclusion: When assessing the RSI the 20-, 40-, and 50-cm drop heights are recommended with this population. When assessing large gro...
TL;DR: The results suggest that BLIs and acceleration might be used as an alternative means to represent the external load during congested match schedules rather than measures related to running speed or distance covered.
Abstract: Purpose: To analyze the effects of a very congested match schedule on the total distance (TD) covered, high-intensity-running (HIR) distance, and frequency of accelerations and body-load impacts (BLIs) performed in a team of under-15 soccer players (N = 10; 15.1 ± 0.2 y, 171.8 ± 4.7 cm, 61 ± 6.0 kg) during an international youth competition. Methods: Using global positioning systems, player performances were repeatedly monitored in 5 matches performed over 3 successive days. Results: Significant differences were observed between matches (P < .05) for the frequency of accelerations per minute, BLIs, and BLIs per minute. No differences were observed for the TD covered, TD run per minute, number of high-intensity runs, distance covered in HIR, per-minute peak running speed attained, or frequency of accelerations. The frequency of accelerations per minute decreased across the competition while BLIs were higher during the final than in all other matches. Conclusions: These results suggest that BLIs and acceler...
TL;DR: Players reduced external physical loads, through declines in movement, over 4 consecutive days of prolonged competitive tennis, and may be affected by tactical changes and pacing strategies.
Abstract: Purpose: To determine how consecutive days of prolonged tennis match play affect performance, physiological, and perceptual responses. Methods: Seven well-trained male tennis players completed 4-h tennis matches on 4 consecutive days. Pre- and postmatch measures involved tennis-specific (serve speed and accuracy), physical (20-m sprint, countermovement jump [CMJ], shoulder-rotation maximal voluntary contraction, isometric midthigh pull), perceptual (Training Distress Scale, soreness), and physiological (creatine kinase [CK]) responses. Activity profile was assessed by heart rate, 3D load (accumulated accelerations measured by triaxial accelerometers), and rating of perceived exertion (RPE). Statistical analysis compared within- and between-days values. Changes (± 90% confidence interval [CI]) ≥75% likely to exceed the smallest important effect size (0.2) were considered practically important. Results: 3D load reduced on days 2 to 4 (mean effect size ± 90% CI –1.46 ± 0.40) and effective playing time reduce...
TL;DR: The supine lnRMSSDx20 CV as measured across 7, 5, and 3 d was the most sensitive marker to the changes in TL in the 3-wk period, and supports the use of the mean and CV of ln RMSSD measured across at least 5 d for reflecting weekly values.
Abstract: Purpose: This study evaluated the 7-d mean and coefficient of variation (CV) of supine and standing ultrashort log-transformed root mean square of successive R-R intervals multiplied by 20 (lnRMSSDx20) obtained with a smartphone application (app) in response to varying weekly training load (TL). In addition, the authors aimed to determine if these values could be accurately assessed in as few as 5 or 3 d/wk. Methods: Nine women from a college soccer team performed daily heart-rate-variability measures with an app in supine and standing positions over 3 wk of moderate, high, and low TL. The mean and CV over 7, 5, and 3 d were compared within and between weeks. Results: The 5- and 3-d measures within each week provided very good to nearly perfect intraclass correlations (ICCs .74–.99) with typical errors ranging from 0.64 to 5.65 when compared with the 7-d criteria. The 7, 5, and 3-d supine CV and the 7-day standing CV were moderately lower during the low-load than the high-load week (P .003–.045, effect si...
TL;DR: Suggestions for standardizing high-speed running and sprint velocity thresholds specific to women's soccer are provided and the authors also comment on using generic vs individualized thresholds, as well as age-related considerations, to establish velocity thresholds.
Abstract: There is no methodological standardization of velocity thresholds for the quantification of distances covered in various locomotor activities for women’s soccer matches, especially for high-speed running and sprinting. Applying velocity thresholds used for motion analysis of men’s soccer has likely created skewed observations about high-intensity movement demands for the women’s game because these thresholds do not accurately reflect the capabilities of elite female players. Subsequently, a cohesive view of the locomotor characteristics of women’s soccer does not yet exist. The aim of this commentary is to provide suggestions for standardizing high-speed running and sprint velocity thresholds specific to women’s soccer. The authors also comment on using generic vs individualized thresholds, as well as age-related considerations, to establish velocity thresholds.
TL;DR: Investigation of match-to-match variability of physical and technical performances in English Premier League players and quantify the influence of positional and contextual factors demonstrates that technical parameters varied more from match to match than physical parameters.
Abstract: Purpose: To investigate match-to-match variability of physical and technical performances in English Premier League players and quantify the influence of positional and contextual factors. Methods: Match data (N = 451) were collected using a multicamera computerized tracking system across multiple seasons (2005–06 to 2012–13). The coefficient of variation (CV) was calculated from match to match for physical and technical performances in selected positions across different match contexts (location, standard, and result). Results: Wide midfielders demonstrated the greatest CVs for total distance (4.9% ± 5.9%) and central midfielders the smallest (3.6% ± 2.0%); nevertheless, all positions exhibited CVs .05, effect size [ES] 0.1–0.3). Central defenders demonstrated the greatest CVs and wide midfielders the lowest for both high-intensity running (20.2% ± 8.8% and 13.7% ± 7.7%, P < .05, ES 0.4–0.8) and sprint distance (32.3% ± 13.8% and 22.6% ± 11.2%, P < .05, ES 0.5–0.8). Technical indicators such as ...
TL;DR: The data show that speed-based distances and metabolic power varied between positional groups, although this was largely related to differences in time spent on field, and higher-speed running may underestimate the demands of match play when compared with high-power distance.
Abstract: Purpose: To describe the metabolic demands of rugby league match play for positional groups and compare match distances obtained from high-speed-running classifications with those derived from high metabolic power. Methods: Global positioning system (GPS) data were collected from 25 players from a team competing in the National Rugby League competition over 39 matches. Players were classified into positional groups (adjustables, outside backs, hit-up forwards, and wide-running forwards). The GPS devices provided instantaneous raw velocity data at 5 Hz, which were exported to a customized spreadsheet. The spreadsheet provided calculations for speed-based distances (eg, total distance; high-speed running, >14.4 km/h; and very-highspeed running, >18.1 km/h) and metabolic-power variables (eg, energy expenditure; average metabolic power; and high-power distance, >20 W/kg). Results: The data show that speed-based distances and metabolic power varied between positional groups, although this was largely related t...
TL;DR: The findings suggest that running intensity varies between and within halves; however, the index used will influence both the magnitude and the temporal identification of peak periods.
Abstract: Purpose: To investigate temporal variation in running intensity across and within halves and evaluate the agreement between match-analysis indices used to identify fluctuations in running intensity in rugby sevens. Methods: Data from a 15-Hz global positioning system (GPS) were collected from 12 elite rugby sevens players during the IRB World Sevens Series (N = 21 full games). Kinematic (eg, relative distance [RD]) and energetic (eg, metabolic power [MP]) match-analysis indices were determined from velocity-time curves and used to investigate between-halves variations. Mean MP and RD were used to identify peak 2-minute periods of play. Adjacent 2-minute periods (prepeak and postpeak) were compared with peak periods to identify changes in intensity. MP and RD were expressed relative to maximal oxygen uptake (VO 2max ) and speed at VO 2max , respectively, and compared in their ability to describe the intensity of peak periods and their temporal occurrence. Results: Small to moderate reductions were present for kinematic (RD; 8.9%) and energetic (MP; 6%) indices between halves. Peak periods (RD = 130 m/min, MP =13 W/kg) were higher (P < .001) than the match average (RD = 94 m/min, MP = 9.5 W/kg) and the prepeak and postpeak periods (P < .001). RD underestimated the intensity of peak periods compared with MP (bias 16%, limits of agreement [LoA] ± 6%). Peak periods identified by RD and MP were temporally dissociated (bias 21 s, LoA ± 212 s). Conclusions: The findings suggest that running intensity varies between and within halves; however, the index used will influence both the magnitude and the temporal identification of peak periods.
TL;DR: The bowling-detection algorithm from the MinimaxX device is sensitive to detect bowling counts in both cricket training and competition, and the number of false positive events increased during competition.
Abstract: Purpose: Bowling workload is linked to injury risk in cricket fast bowlers. This study investigated the validity of microtechnology in the automated detection of bowling counts and events, including run-up distance and velocity, in cricket fast bowlers. Method: Twelve highly skilled fast bowlers (mean ± SD age 23.5 ± 3.7 y) performed a series of bowling, throwing, and fielding activities in an outdoor environment during training and competition while wearing a microtechnology unit (MinimaxX). Sensitivity and specificity of a bowling-detection algorithm were determined by comparing the outputs from the device with manually recorded bowling counts. Run-up distance and run-up velocity were measured and compared with microtechnology outputs. Results: No significant differences were observed between direct measures of bowling and nonbowling events and true positive and true negative events recorded by the MinimaxX unit (P = .34, r = .99). The bowling-detection algorithm was shown to be sensitive in both traini...
TL;DR: The results indicate that a polarized training-intensity distribution that has been reported in elite endurance athletes does not occur in professional Australian Football.
Abstract: Purpose: To examine the training periodization of an elite Australian Football team during different phases of the season. Methods: Training-load data were collected during 22 wk of preseason and 23 wk of in-season training. Training load was measured using the session rating of perceived exertion (session-RPE) for all training sessions and matches from 44 professional Australian Football players from the same team. Training intensity was divided into 3 zones based on session-RPE (low, 4 AU and 7 AU). Training load and intensity were analyzed according to the type of training session completed. Results: Higher training load and session duration were undertaken for all types of training sessions during the preseason than in-season (P < .05), with the exception of “other” training (ie, re/prehabilitation training, cross-training, and recovery activities). Training load and intensity were higher during the preseason, with the exception of games, where greater load and intensi...
TL;DR: This is the first study to demonstrate a clear beneficial effect of isolated core training on 50-m front-crawl swim performance, and the authors made probabilistic magnitude-based inferences about the effect of the coreTraining on50-m swim time and functionally relevant measures of core function.
Abstract: Purpose: To quantify the effects of a 12-wk isolated core-training program on 50-m front-crawl swim time and measures of core musculature functionally relevant to swimming. Methods: Twenty national-level junior swimmers (10 male and 10 female, 16 ± 1 y, 171 ± 5 cm, 63 ± 4 kg) participated in the study. Group allocation (intervention [n = 10], control [n = 10]) was based on 2 preexisting swim-training groups who were part of the same swimming club but trained in different groups. The intervention group completed the core training, incorporating exercises targeting the lumbopelvic complex and upper region extending to the scapula, 3 times/wk for 12 wk. While the training was performed in addition to the normal pool-based swimming program, the control group maintained their usual pool-based swimming program. The authors made probabilistic magnitude-based inferences about the effect of the core training on 50-m swim time and functionally relevant measures of core function. Results: Compared with the control g...
TL;DR: Findings suggest that the running demands of rugby league fluctuate vastly across a match, and fullbacks were the only position to exhibit a greater running intensity than any other position, and therefore training prescription should reflect this.
Abstract: Rugby league coaches often prescribe training to replicate the demands of competition. The intensities of running drills are often monitored in comparison with absolute match-play measures. Such measures may not be sensitive enough to detect fluctuations in intensity across a match or to differentiate between positions. Purpose: To determine the position- and duration-specific running intensities of rugby league competition, using a moving-average method, for the prescription and monitoring of training. Methods: Data from a 15-Hz global positioning system (GPS) were collected from 32 professional rugby league players across a season. The velocity–time curve was analyzed using a rolling-average method, where maximum values were calculated for 10 different durations, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 min, for each player across each match. Results: There were large differences between the 1- and 2-min rolling averages and all other rolling-average durations. Smaller differences were observed for rolling ave...
TL;DR: The results of this investigation indicate that females may be more prone to producing forces asymmetrically than males during WtD and jumping tasks and that absolute strength may play a larger role in influencing asymmetry magnitude than sex.
Abstract: The purpose of this investigation was to determine the existence of bilateral strength and force-production asymmetry and evaluate possible differences based on sex, as well as strength level. Asymmetry was assessed during weight-distribution (WtD) testing, unloaded and lightly loaded static- (SJ) and countermovement-jump (CMJ) testing, and isometric midthigh-pull (IMTP) strength testing. Subjects included 63 athletes (31 male, 32 female) for WtD, SJ, and CMJ tests, while 129 athletes (64 male, 65 female) participated in IMTP testing. Independent-samples t tests were used to determine possible differences in asymmetry magnitude between males and females, as well as between strong and weak athletes. Cohen d effect-size (ES) estimates were also used to estimate difference magnitudes. Statistically different asymmetry levels with moderate to strong ESs were seen between males and females in WtD, 0-kg SJ (peak force [PF]), 20-kg SJ (peak power [PP]), 0-kg CMJ (PF, PP, net impulse), and 20-kg CMJ (PF), but no statistical differences were observed in IMTP variables. Dividing the sample into strong and weak groups produced statistically significant differences with strong ES estimates in IMTP PF and rate of force development, and many ESs in jump symmetry variables increased. The results of this investigation indicate that females may be more prone to producing forces asymmetrically than males during WtD and jumping tasks. Similarly, weaker athletes displayed more asymmetry than stronger athletes. This may indicate that absolute strength may play a larger role in influencing asymmetry magnitude than sex.
TL;DR: This study provides updated benchmark VO2max values for Olympic-medal-level performance in winter endurance disciplines and can serve as a guideline of the requirements for future elite athletes.
Abstract: Purpose: To generate updated Olympic-medal benchmarks for VO2max in winter endurance disciplines, examine possible differences in VO2max between medalists and nonmedalists, and calculate gender difference in VO2max based on a homogeneous subset of world-leading endurance athletes. Methods: The authors identified 111 athletes who participated in winter Olympic Games/World Championships in the period 1990 to 2013. All identified athletes tested VO2max at the Norwegian Olympic Training Center within ±1 y of their championship performance. Testing procedures were consistent throughout the entire period. Results: For medal-winning athletes, the following relative VO2max values (mean:95% confidence intervals) for men/women were observed (mL · min–1 · kg–1): 84:87-81/72:77-68 for cross-country distance skiing, 78:81-75/68:73-64 for cross-country sprint skiing, 81:84-78/67:73-61 for biathlon, and 77:80-75 for Nordic combined (men only). Similar benchmarks for absolute VO2max (L/min) in male/female athletes ...
TL;DR: The results suggest that technical and tactical differences, rather than activity profiles, may be the distinguishing factor between successful and less-successful rugby league teams.
Abstract: Purpose: To quantify activity profiles in approximately 5-min periods to determine if the intensity of rugby league match play changes after the most intense period of play and to determine if the intensity of activity during predefined periods of match play differ between successful and less-successful teams playing at an elite standard. Methods: Movement was recorded using a MinimaxX global positioning system (GPS) unit sampling at 10 Hz during 25 rugby league matches, equating to 200 GPS files. Data for each half of match play were separated into 8 equal periods. These periods represented the most intense phase of match play (peak period), the period after the most intense phase of match play (subsequent period), and the average demands of all other periods in a match (mean period). Two rugby league teams were split into a high-success and a low-success group based on their success rates throughout their season. Results: Compared with their less-successful counterparts, adjustables and hit-up forwards ...
TL;DR: A review of potential confounding variables in relation to common testing environments in exercise and sports science and some recommendations are presented with the goal of reducing possible threats to internal validity.
Abstract: Internal validity refers to the degree of control exerted over potential confounding variables to reduce alternative explanations for the effects of various treatments. In exercise and sports-science research and routine testing, internal validity is commonly achieved by controlling variables such as exercise and warm-up protocols, prior training, nutritional intake before testing, ambient temperature, time of testing, hours of sleep, age, and gender. However, a number of other potential confounding variables often do not receive adequate attention in sports physiology and performance research. These confounding variables include instructions on how to perform the test, volume and frequency of verbal encouragement, knowledge of exercise endpoint, number and gender of observers in the room, influence of music played before and during testing, and the effects of mental fatigue on performance. In this review the authors discuss these variables in relation to common testing environments in exercise and sports science and present some recommendations with the goal of reducing possible threats to internal validity.
TL;DR: Notable differences in the volume of activity were displayed across the functional classification groups, however, the specific on-court requirements of defensive and offensive match roles appeared to influence the intensity of match activities, and consequently training prescription should be structured accordingly.
Abstract: To quantify the activity profiles of elite wheelchair rugby and establish classification-specific arbitrary speed zones. Additionally, indicators of fatigue during full matches were explored. Methods: Seventy-five elite wheelchair rugby players from eleven national teams were monitored using a radio-frequency based, indoor tracking system across two international tournaments. Players who participated in complete quarters (n = 75) and full matches (n = 25) were included and grouped by their International Wheelchair Rugby Federation functional classification: group I (0-0.5), II (1.0-1.5), III (2.0-2.5) and IV (3.0-3.5). Results: During a typical quarter, significant increases in total distance (m), relative distance (m·minˉ¹), and mean speed (m·sˉ¹) were associated with an increase in classification group (P < 0.001), with the exception of group III and IV. However, group IV players achieved significantly higher peak speeds (3.82 ± 0.31 m·sˉ¹) than groups I (2.99 ± 0.28 m·sˉ¹), II (3.44 ± 0.26 m·sˉ¹) and III (3.67 ± 0.32 m·sˉ¹). Groups I and II differed significantly in match intensity during very low/low speed zones and the number of high-intensity activities in comparison with groups III and IV (P < 0.001). Full match analysis revealed that activity profiles did not differ significantly between quarters. Conclusions: Notable differences in the volume of activity were displayed across the functional classification groups. However, the specific on-court requirements of defensive (I and II) and offensive (III and IV) match roles appeared to influence the intensity of match activities and consequently training prescription should be structured accordingly.
TL;DR: Findings indicate that gender-specific running and dribbling differences might exist in semiprofessional basketball, and position-specific variations between female and male basketball players should be considered.
Abstract: Purpose: To compare game activity demands between female and male semiprofessional basketball players. Methods: Female (n = 12) and male (n = 12) semiprofessional basketball players were monitored across 3 competitive games. Time–motion-analysis procedures quantified player activity into predefined movement categories across backcourt (BC) and frontcourt (FC) positions. Activity frequencies, durations, and distances were calculated relative to live playing time (min). Work:rest ratios were also calculated using the video data. Game activity was compared between genders for each playing position and all players. Results: Female players performed at greater running work-rates than male players (45.7 ± 1.4 vs. 42.1 ± 1.7 m/min, P = .05), while male players performed more dribbling than female players (2.5 ± 0.3 vs. 3.0 ± 0.2 s/min; 8.4 ± 0.3 vs. 9.7 ± 0.7 m/min, P = .05). Positional analyses revealed that female BC players performed more low-intensity shuffling (P = .04) and jumping (P = .05), as well as lon...
TL;DR: The greatest performance differences between the skating and classical techniques and between the 2 genders were found on uphill terrain, and these speed differences could not be explained by variations in exercise intensity.
Abstract: Purpose: To compare the speed and heart-rate profiles during international skating and classical competitions in male and female world-class cross-country skiers. Methods: Four male and 5 female skiers performed individual time trials of 15 km (men) and 10 km (women) in the skating and classical techniques on 2 consecutive days. Races were performed on the same 5-km course. The course was mapped with GPS and a barometer to provide a valid course and elevation profile. Time, speed, and heart rate were determined for uphill, flat, and downhill terrains throughout the entire competition by wearing a GPS and a heart-rate monitor. Results: Times in uphill, flat, and downhill terrain were ~55%, 15–20%, and 25–30%, respectively, of the total race time for both techniques and genders. The average speed differences between skating and classical skiing were 9% and 11% for men and women, respectively, and these values were 12% and 15% for uphill, 8% and 13% for flat (all P < .05), and 2% and 1% for downhill terrain....
TL;DR: M-ST improved endurance performance and enabled a higher power output, whereas N-ST induced no change, thereby inferring a perceptual benefit through M-ST.
Abstract: Purpose: Unpleasant physical sensations during maximal exercise may manifest themselves as negative cognitions that impair performance, alter pacing, and are linked to increased rating of perceived exertion (RPE). This study examined whether motivational self-talk (M-ST) could reduce RPE and change pacing strategy, thereby enhancing 10-km time-trial (TT) cycling performance in contrast to neutral self-talk (N-ST). Methods: Fourteen men undertook 4 TTs, TT1–TT4. After TT2, participants were matched into groups based on TT2 completion time and underwent M-ST (n = 7) or N-ST (n = 7) after TT3. Performance, power output, RPE, and oxygen uptake (VO2) were compared across 1-km segments using ANOVA. Confidence intervals (95%CI) were calculated for performance data. Results: After TT3 (ie, before intervention), completion times were not different between groups (M-ST, 1120 ± 113 s; N-ST, 1150 ± 110 s). After M-ST, TT4 completion time was faster (1078 ± 96 s); the N-ST remained similar (1165 ± 111 s). The M-ST gro...