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Field referees (FRs) need to move throughout the pitch to identify any infringements of the game's laws. Their performance depends on technical, tactical, physical, physiological, and mental factors. This retrospective study aimed to examine and assess the physical and physiological parameters as a function of time in elite association football referees during official matches. Global positioning system (match time, distance in different intensity ranges [low-intensity, high-speed, very high-speed running, and sprinting], average and peak speed, distance in accelerations or decelerations) and heart rate (average and peak) data from 212 national and international football matches were analyzed. A linear mixed-model analysis was performed to assess the differences between halves and between the three 15-minute sections of each half-time for all the physical and physiological variables collected. A significant effect of match half was found for the game time (p < 0.001) and the standing time (p = 0.005), both higher in the second half, and for the average speed (p = 0.017), which was lower in the second half. Total distance (p < 0.001), low-intensity distance (p = 0.004), and average speed (p = 0.007) all showed a reduction as a function of time. More than 7.800 high-speed intervals were detected. Accelerative actions within 3 seconds characterized most of the high-speed efforts of an FR during a match. Significant differences emerged in the way the match intensity is distributed across the match, analyzed both in halves (first vs. second) and 15-minute intervals within each half. It is important to emphasize the importance of high-speed training with a focus on a faster transition from low- to high-speed running to keep up with the play to get into an appropriate position and subsequently make the correct decisions. [ABSTRACT FROM AUTHOR]

This study examined the effect of self-efficacy, effort, and perceived performance on positive well-being (PWB) and psychological distress (PD) following high-intensity resistance training sessions in collegiate student-athletes. An observational field study design was used to collect data before and after resistance training sessions in a 4-week preseason strength training block. A multilevel model assessed day-level and person-level variance in acute PWB and PD. Interaction terms were also tested at the day level. Alpha was set at 0.05. Within a 4-week training block, training session intensity did not predict changes in acute psychological responses. After controlling for an athlete's preexercise psychological state, higher self-efficacy, daily effort, and perceived performance predicted higher PWB and lower PD following training (p < 0.05). Self-efficacy moderated the relationships of daily effort and performance with PD (p < 0.05). When athletes experienced lower self-efficacy, producing a higher effort and perceiving better performance reduced the negative psychological response. These findings highlight the important mediating role of cognitive variables in the acute psychological response to high-intensity resistance training. Coaches should identify and mitigate low cognitive states to facilitate a positive psychological response to resistance training. This strategy promotes a positive psychological response without altering training prescription. [ABSTRACT FROM AUTHOR]

The benefits of strength and conditioning (S&C) for improving judo performance and reducing injuries have been widely studied. However, the S&C practices used and perspectives held by those delivering S&C have yet to be elucidated. Therefore, this study investigated the S&C practices and perspectives of judokas and S&C coaches working within judo. Forty-two judokas and 9 S&C coaches completed an online survey comprising 6 sections: (a) written informed consent; (b) background information; (c) education, qualifications, and prescription; (d) views on S&C (e) exercise selection; and (f) issues and improvements. Frequency analysis was used to report responses to fixed-response questions and thematic analysis for open-ended questions. Results indicated that S&C coaches were primarily responsible for delivering S&C programs (60%), and S&C information was predominantly sourced from S&C coaches (43%). Strength and conditioning was deemed very important for randori (78-88%), overall judo performance (67-79%), and judo fitness (62-78%). Similarly, S&C was considered very important for the development of speed and power (76-89%), strength (71-89%), and injury reduction (69-78%). Novel findings were also observed, such as integrating judo-specific training within S&C practice, which may be partly explained by more S&C coaches holding judo belts (67%) than S&C qualifications (11%). This study supports practitioners delivering S&C in judo by offering a base of information to critique or align with their existing S&C practices and perspectives. Furthermore, our results may help identify potential gaps between methods used, proposed guidelines, and actual practice, facilitating the development of research and education resources tailored to the current climate. [ABSTRACT FROM AUTHOR]

Zukowski, MH, Jordan, MJ, and Herzog, W. Modeling the early and late cceleration phases of the sprint start in elite long track speed skaters. J Strength Cond Res 38(2): 236-244, 2024--This study established the reliability of an exponential function to model the change in velocity during the speed skating sprint start and the validity of associated model parameters in a group of subelite and elite long track speed skaters. Long track speed skaters (n538) performed maximal effort 50-mon-ice accelerations froma standing start while tethered to a horizontal robotic resistance device that sampled position and time data continuously. An exponential function was applied to the raw data to model the change in velocity throughout the acceleration phase and compute the maximal skating speed (MSS), maximal acceleration capacity (MAC), maximum relative net horizontal power (PMax), and an acceleration-time constant (t). All constructed models provided a sufficient fit of the raw data (R-squared. 0.95, mean bias, 2%). Intraday reliability of all model parameters ranged from good to excellent (intraclass correlation coefficient .0.8 and coefficient of variation, 5%). Strong negative correlations (r: 20.72 to 20.96) were observed between MSS and PMax and the 10 and 20 m split times measured with the robotic resistance and with 100 split times obtained from500mraces. Moderate-to-large between-group differenceswere observed inMSS, MAC, and PMax between the elite vs. subelite speed skaters (Cohen d effect sizes: 1.18-3.53). Our results indicate that monoexponentialmodeling is a valid and reliable method of monitoring initial acceleration performance in elite level long track speed skaters. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the relationship between agility performance and cognitive functions measured under laboratory conditions among elite young soccer players. Twenty-five, elite, young, male soccer players (12.3 6 0.4 years, 155.4 6 7.6 cm, 42.6 6 6.9 kg) completed a battery of field tests, including 5-, 10-, 20-m sprints, change of direction speed (CODS), standing long jump, and an agility test based on a human stimulus. Subjects also completed choice reaction (RT, S3) and reactive stress tolerance (DT, S1) tests on the Vienna Test System. There was a moderate significant relationship (p, 0.05) found between mean reaction time and mean motor time during the choice reaction task and decision time in the agility test. Decision time also showed a large significant correlation (p, 0.05) with total time in the agility test. No significant correlation was found between total time in the agility test and variables measured during RT and DT tests. No significant correlations were found between agility test results and results from straight line sprints, CODS, and standing long jump tests. The results of this study suggest that choice reaction time is related to decision-making speed during the agility task used in this study and can have an indirect effect on agility performance in elite young soccer players. Further studies assessing the relationship between different cognitive functions and agility performance in different sports and age categories could help in the identification of determinant cognitive functions in perceptual and decision-making factors of agility. [ABSTRACT FROM AUTHOR]

Ruiz-Alias, SA, Pe' rez-Castilla, A, Soto-Hermoso, VM, and Garc'ıa-Pinillos, F. Influence of the world athletics stack height regulation on track running performance. J Strength Cond Res 37(11): 2260-2266, 2023--A new footwear regulation based on limiting the stack height (i.e., amount of material between the feet and the ground) has been established byWorld Athletics to ensure that performance is achieved through the primacy of human effort over technology in running shoes. Analyzing the effect of legal and illegal shoes on running performance is therefore needed to determine its effectiveness. Thus, this study aimed (a) to compare the effect of 2 footwear models categorized as legal and illegal by the World Athletics regulation on track running performance and (b) to analyze the derived metrics of the athletes' biomechanics when using each footwear model at racing paces. Within 1 week, 14 highly trained athletes performed 2 testing sessions composed of 2 time trials of 9- and 3-minute duration with 30 minutes of recovery between them. The athletes wore the "Nike ZoomX Dragonfly" track spikes model and the "Nike ZoomX Vaporfly Next % 2" marathon shoe model in a counterbalanced randomized order. The results revealed that (a) there was only a small worthwhile improvement in the 3-minute time trial when using themarathon shoes of 0.97%(20.04 to 1.98%) and (b) there was amain effect of footwear in 7 of the 9 biomechanical variables analyzed (p # 0.050). The ground contact time was the unique performance predictor (p 5 0.005, adjusted R2 5 0.476). Altogether, the use of legal and illegal running shoes altered the runners form, which only influenced the mid-distance performance. [ABSTRACT FROM AUTHOR]

This study assessed player (i.e., lower-body strength and power and aerobic fitness) and environmental (e.g., venue) factors and their effects on the physical (e.g., distance) and technical (e.g., kicks) demands of Australian football (AF). Relative distance, high-speed running (HSR), and acceleration efforts for 19 matches by 33 players in a West AF League team were analyzed from global positioning system data split into periods of successful offense and defense and maximum ball in play (BiP) periods, as well as technical actions. Lower-body strength and power, and aerobic fitness were evaluated using a one-repetition trap-bar deadlift, countermovement jump, 2-km time trial, and Yo-Yo intermittent fitness test, respectively. In matches played at home, distance (p < 0.001, ES = 0.39) and HSR (p < 0.001, ES = 0.34) were significantly reduced during successful defense. In addition, tackle rate was significantly increased (p = 0.003, ES = 0.16) during successful defense when playing at home. Trap-bar deadlift relative to mass significantly increased relative distance (p = 0.004, ES = 0.51) and HSR (p = 0.029, ES = 0.40) in successful offense. In successful defense, superiortime trial performance significantly increased relative distance (p < 0.001, ES = 0.58), HSR (p < 0.001, ES = 0.59), and acceleration efforts (p = 0.017, ES = 0.44), while relative distance (p < 0.001, ES = 0.62) and HSR (p = 0.004, ES = 0.52) were also increased during maximum BiP periods. The results demonstrate that player factors have the largest effect on the physical and technical performance of AF players. [ABSTRACT FROM AUTHOR]

The increased participation in trail running (TR) races and the emergence of official international races have increased the performance level of the world best trail runners. The aim of this study was to compare cost of running (Cr) and biomechanical and neuromuscular characteristics of elite trail runners with their lower level counterparts. Twenty elite (10 females; ELITE) and 21 experienced (10 females; EXP) trail runners participated in the study. Cr and running biomechanics were measured at 10 and 14 km·h-1 on flat and at 10 km·h-1 with 10% uphill incline. Subjects also performed maximal isometric voluntary contractions of knee and hip extensors and knee flexors and maximal sprints on a cycle ergometer to assess the power-torque-velocity profile (PTVP). Athletes also reported their training volume during the previous year. Despite no differences in biomechanics, ELITE had a lower Cr than EXP (p < 0.05). Despite nonsignificant difference in maximal lower-limb power between groups, ELITE displayed a greater relative torque (p < 0.01) and lower maximal velocity (p < 0.01) in the PTVP. Females displayed shorter contact times (p < 0.01) compared with males, but no sex differences were observed in Cr (p > 0.05). No sex differences existed for the PTVP slope, whereas females exhibited lower relative torque (p < 0.01) and velocity capacities (p < 0.01) compared with males. Although not comprehensively assessing all determining factors of TR performance, those data evidenced level and sex specificities of trail runners in some factors of performance. Strength training can be suggested to lower level trail runners to improve Cr and thus TR performance. [ABSTRACT FROM AUTHOR]

Rossiter, A, Warrington, GD, and Comyns, TM. Effects of long-haul travel on recovery and performance in elite athletes: a systematic review. J Strength Cond Res 36(11): 3234–3245, 2022—Elite athletes are often required to travel long-haul (LH) across numerous time zones for training or competition. However, the extent to which LH travel affects elite athlete performance remains largely unknown. The purpose of this systematic literature review was to critically evaluate available evidence on the effects of LH travel on elite athlete psychometric, physiological, sleep, and performance markers. Electronic database searches of PubMed, SPORTDiscus, Scopus, and Web of Science were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were eligible for inclusion if subjects were identified as elite athletes who embarked on a LH flight (>6 hours) and used an outcome measurement of recovery or performance after the flight. Studies that were retrospective, used light therapy or pharmacological interventions were not included. Of 2,719 records assessed, 14 studies comprising a total of 197 athletes from 6 sports met the inclusion criteria. There was an increase in perceived jet lag and disturbance to various physiological markers after LH travel; however, there was minimal disturbance in other psychometric markers. Sleep was not negatively affected by LH travel. Of 10 studies that assessed performance, 3 found decrements in indirect markers of performance. Elite athletes perceived themselves to be jet lagged and experienced disturbance to various physiological mechanisms after LH travel; however, the effect on performance was inconclusive. Future research would benefit from higher quality studies with improved control measures, larger sample sizes from a wider variety of sports, and use of ecologically valid measures of circadian rhythm and athletic performance. [ABSTRACT FROM AUTHOR]

Jobe, TK, Shaffer, HN, Doci, CL, and Gries, KJ. Sex differences in performance and depth of field in the United States Olympic trials. J Strength Cond Res 36(11): 3122–3129, 2022—Recently, there has been an increased discussion on the role of sex as a variable in human performance. Although there likely remains sociological factors, we can estimate biological sex differences in human performance by comparing finishing times in elite men and women. We sought to determine the effect of sex on running and swimming velocity and depth of field in events of varying lengths in the previous 25 years. Finishing times from United States Olympic trials in running events (100 m to marathon) and freestyle swimming (50–1,500 m) from 1996 to 2021 were collected. Sex differences in velocity were calculated for each year (trends), place (first through seventh), and depth of field (nth place/first place). Significance was set at p ≤ 0.05. Men were 9–13% faster than women in all running events (p ≤ 0.05). The 100-m dash (9%) had the lowest sex difference compared with races of longer distance (p ≤ 0.05). In swimming, men were faster in all events (6–12%, p ≤ 0.05), in which sex differences generally decreased with longer distances. Depth of field was similar between men and women in all running and swimming events. No differences in the analyzed variables were observed from 1996 to 2021. These data suggest that elite men are 9% faster in the 100 m compared with running races of longer distances (~12%). Sex differences in swimmers tended to get smaller as duration increased. Although participation and other sociological factors in these events may play a role, these sex differences warrant further discussion on the role of sex in athletic competition. [ABSTRACT FROM AUTHOR]

Everett, KLA, Chapman, DW, Mitchell, JA, and Ball, N. Changes in loaded countermovement jumps during precompetition and competition training mesocycles in elite rowers. J Strength Cond Res 36(9): 2622–2627, 2022—To assess changes in velocity, displacement, and power as an indicator of neuromuscular fatigue (NMF) within and between precompetition and competition mesocycles in elite male rowers using loaded countermovement jumps (CMJs). Twenty highly trained rowers completed regular training (on-water rowing, rowing ergometer, and resistance training sessions) in 2 consecutive mesocycles. Athletes completed a single set of 6 loaded (20 kg) CMJs in the first and final week of each mesocycle. Countermovement jumps were assessed for jump height (JH), eccentric displacement, mean velocity (MV), eccentric MV (EMV), and mean power. Changes between time points were reported as Cohen's d effect sizes (95% confidence interval [CI]). The magnitude of the differences was also considered based on their relative strength levels using a linear mixed model. Within the precompetition mesocycle, trivial-to-small reductions for all variables (0.5–4.1%) were observed. During the competition mesocycle, trivial-to-small increases were shown for EMV (1.4%) and eccentric displacement (2.0%) with no change in JH and small reductions in MV (0.5%) and mean power (2.8%). No differences between the precompetition and competition mesocycles were shown. Only mean power showed a significant reduction in weaker athletes (3.2%) compared with stronger athletes (2.3%). Training completed during a precompetition and competitive mesocycle did not result in significant decreases in athlete's loaded CMJ performance, indicating that NMF was minimized. Alternatively, use of a loaded CMJ may not be sensitive enough to observe NMF in elite rowers during the mesocycle immediately leading into and during a competition mesocycle. [ABSTRACT FROM AUTHOR]

Thomas, C, Delfour-Peyrethon, R, Dorel, S, and Hanon, C. Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. J Strength Cond Res 36(9): 2602–2609, 2022—This study aimed to determine the effects of pre-exercise alkalosis in world-class cyclists on their general (rate of perceived exertion [RPE]) and local (category-ratio scale [CR10]) perceived rates of exertion and acid-base status during 2 types of training sessions. Eight world-class cyclists ingested either sodium bicarbonate (BIC) or a placebo (PLA) in a double-blind and randomized order before performing 4 × 1,000 m constant-power sprints (CP) or 3 × 500 m all-out sprints (AO), with 20 minutes of recovery time between each session. For AO, the performance was assessed through the cycling sprint velocity and a squat jump test during recovery. During both tests, RPE, CR10, and acid-base status were measured. Sodium bicarbonate ingestion was effective in inducing pre-exercise alkalosis, compared with a PLA (p < 0.05). During CP, performance and RPE were the same for BIC and PLA (p > 0.05) with no time effect. The CR10 increased for the last sprint in PLA (p < 0.05) but was attenuated in BIC (BIC: 6 vs. PLA: 8.2; p < 0.05), whereas there was no difference in acid-base status. During AO, RPE and CR10 increased with time, with no BIC effect, whereas blood lactate concentration was different (p < 0.05). Sodium bicarbonate supplementation had no effect on overall repeated sprints (p > 0.05). However, world-class athletes responded to BIC with higher squat jump performance than the PLA condition after AO (p < 0.05). Our results suggest a positive influence of pre-exercise alkalosis in world-class cyclists on local perception of efforts after constant load sprints and an attenuation of muscle power output decline postsprint, as evidenced by improved squat jump performance after all-out cycling effort. [ABSTRACT FROM AUTHOR]

Botelho, R, Abad, CCC, Spadari, RC, Winckler, C, Garcia, MC, and Guerra, RLF. Psychophysiological stress markers during preseason among elite female soccer players. J Strength Cond Res 36(6): 1648–1654, 2022—This study aimed to investigate changes and correlations between mood states and various physiological stress markers after a 7-week preseason period among elite female soccer players. Twenty-four elite female soccer players participated in this study (26.4 ± 3.7 years). Their internal training load, mood states, day and evening salivary testosterone and cortisol concentrations, blood creatine kinase concentration (CK), and heart rate variability (HRV) were assessed during the first week of preseason (PRE), and again 7 weeks after a systematic training period (END). After the preseason, there were significant increases in subject negative mood scales (p ≤ 0.03; Effect Size [ES] > 0.60), total mood scores (p = 0.01; QI = 100/0/0; ES = 1.32), day and evening testosterone and cortisol concentrations (p ≤ 0.03; ES > 0.54), and CK concentrations (p = 0.01; QI = 100/0/0; ES = 1.54). Correlations were found between cortisol and tension (r = 0.53 and 0.60; p ≤ 0.02), cortisol and confusion (r = 0.75; p = 0.01), and cortisol and the LF/HF index of HRV (r = −0.52; p = 0.04). Mood states (except vigor), salivary testosterone, and cortisol concentrations, as well as CK, showed significant changes after a 7-week systematic training system. The cortisol was the factor most highly related to various mood states (including tension and confusion), and with the HRV indices. Coaches and researchers can use these data to design, monitor, and control soccer training programs, in particular throughout the preseason period. [ABSTRACT FROM AUTHOR]

Minahan, C, Newans, T, Quinn, K, Parsonage, J, Buxton, S, and Bellinger, P. Strong, Fast, Fit, Lean, and Safe: A positional comparison of physical and physiological qualities within the 2020 Australian Women's Rugby League team. J Strength Cond Res 35(12S): S11–S19, 2021—The purpose of the present study was to report the physical and physiological characteristics of elite women Rugby League (RL) players. Thirty-nine women (25.6 ± 4.3 years, 171.3 ± 7.7 cm, 83.5 ± 13.9 kg) from the 2020 Australian women's RL squad were recruited for this study. Players were categorized as adjustables (n = 7), backs (n = 15), or forwards (n = 17) for analysis. Each player was assessed for anthropometry, body composition (dual-energy X-ray absorptiometry), speed (5, 10 and 20 m sprint times), lower-body power (countermovement jump), upper-body power (medicine ball throw and explosive push up force), estimated one repetition maximum (e1RM) bench press, squat and bench pull, isometric mid-thigh pull strength, eccentric knee flexor strength, isometric hip abduction and adduction, and intermittent endurance performance (30–15 intermittent fitness test; 30–15 IFT). Linear mixed models were performed to compare positional groups. Forwards were significantly heavier and had greater fat mass, fat-free mass, and body fat percentage compared with backs and adjustables (P < 0.01). Backs were faster over 20 m compared with forwards (P = 0.025), whereas forwards had a lower 30–15 IFT peak velocity and estimated V̇ o 2peak compared with backs and adjustables. Nonetheless, when including body mass in the model, there were no differences between groups in 30–15 IFT peak velocity. There were no significant differences in other variables. These results provide contemporary benchmark physical, physiological, and anthropometric data for elite women RL players, which can inform recruitment, selection, training, and testing. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Bush, CM, Wilhelm, AJ, Lavallee, ME, and Deitch, JR. Early sport specialization in elite weightlifters: weightlifting injury occurrence and relevant opinions. J Strength Cond Res 35(11): 3260–3264, 2021—Sports specialization has been associated with increased injury and burnout. This study sought to determine the age, rate of injury, influence to specialize, and opinions surrounding the impact of sports specialization in attainment of elite-level weightlifting status. A link to an anonymous survey was distributed to the top 20 weightlifters in each weight class (8 male and 7 female weight classes). The survey questioned athletes about both age and motivation to specialize, previous injuries and/or surgeries, and level of competition. Injuries and surgeries were compared between those who specialized at the Youth level (≤age 16), Junior level (ages 17–20), and nonspecialized weightlifters. One hundred forty-one athletes (47.0%) completed the survey. Sixteen subjects (11.3%) specialized at the Youth level, 18 (12.8%) specialized at the Junior level, and the remaining 107 (75.9%) did not specialize before age 21. There was a statistically significant difference in the occurrence of injury before age 21 between weightlifters specializing at the Youth level and those who did not specialize (Χ2(1) = 22.4, p < 0.0001). There were no statistically significant differences in serious injury after age 21 between groups. Weightlifters cited primarily themselves (45.4%) or coach (43.1%) as a driving influence to specialize. The majority of athletes (68.8%) felt that specializing during the Youth age group was not necessary to achieve elite status. Despite a relatively small sample size, injuries occurred more frequently in weightlifters specializing at younger ages, suggesting that risks associated with early sport specialization also apply to weightlifters. These risks should be considered before implementing an early specialization training regimen. [ABSTRACT FROM AUTHOR]

Kantanista, A, Kusy, K, Pospieszna, B, Korman, P, Wieliński, D, and Zieliński, J. Combined analysis of blood ammonia and lactate levels as a practical tool to assess the metabolic response to training sessions in male and female sprinters. J Strength Cond Res 35(9): 2591-2598, 2021-Previous research has mainly focused on blood ammonia and lactate concentration changes in response to exercise in laboratory settings. The aim of this study was to present a combined analysis of blood ammonia and lactate levels obtained during various training sessions performed under real training conditions. Differences between the sexes were also analyzed. The study subjects included 9 male and 8 female sprinters competing at the international level. The two-way analyses of variance, with repeated measures (time × sex), for lactate and blood ammonia concentrations during strength, speed (only lactate), speed with baton exchange, and speed endurance training sessions were significant. Blood ammonia and lactate levels obtained during repeated sprints were higher in male than female athletes. Peak lactate concentrations obtained from different training sessions were different in the female (F(3, 18) = 49.82, p = 0.001, X2 = 0.893) and male (F(3, 21) = 312.26, p = 0.001, X2 = 0.978) athletes; post hoc analyses of the men and women showed differences in maximum lactate concentration between training sessions, except in the speed and strength sessions. Peak ammonia concentrations obtained in the different training sessions were also different in the female (F(3, 18) = 121.06, p = 0.001, X2 = 0.953) and male (F(3, 21) = 196.04, p = 0.001, X2 = 0.965) athletes; in both the men and women, significant differences in maximum blood ammonia concentrations were found between the training sessions, except for the speed and speed with baton exchange training sessions. The results of this study indicate that the combined analysis of lactate and blood ammonia concentration provides the coach with valuable additional information about the level of adenosine triphosphate breakdown, the energy system contribution involved in muscle energy coverage during very short, repeated maximal sprints, and, most importantly, allows the coach to check whether preworkout goals were actually met. [ABSTRACT FROM AUTHOR]

The first aim of this study was to quantify and compare asymmetries among professional soccer and cricket athletes. The second aim was to examine the association between asymmetries and performance within both groups. Professional soccer (n = 18) and cricket (n = 23) athletes performed single-leg countermovement jumps, single-leg drop jumps (SLDJs), a 10-m sprint, and 505 change of direction speed (CODS) tests. Interlimb asymmetries were calculated as a standard percentage difference, Mann-Whitney U tests conducted to establish systematic bias between groups, and Spearman's r correlations used to establish the relationship between asymmetry scores and speed and CODS performance. Soccer athletes sprinted faster, jumped higher, and had a greater reactive strength index (RSI) score than cricket athletes (p < 0.05). However, cricketers showed reduced ground contact times compared with footballers during the SLDJ (p < 0.05). The cricket group showed significantly greater jump height (asymmetry = 11.49 vs. 6.51%; p = 0.015) and RSI (asymmetry = 10.37 vs. 5.95%; p = 0.014) asymmetries compared with soccer players. These metrics were also associated with slower 505 times in the cricket group only (r = 0.56-0.74; p < 0.01). These results show that between-limb asymmetries exhibit no association with speed and CODS in elite soccer players but are associated with reduced CODS in elite cricketers. Thus, the reduction of interlimb asymmetries may be of greater consideration when working with cricket vs. soccer athletes. [ABSTRACT FROM AUTHOR]

Different approaches, such as providing augmented feedback (AF) or adopting an external focus of attention (EF), have been shown to directly enhance performance in recreational athletes. Furthermore, research has shown that combining AF with EF (AF + EF) results in superior performance compared to AF and EF alone. Here, we tested the influence of AF, EF, AF + EF, and an internal focus of attention (IF) on service speed in elite tennis players. High-level national tennis players (19.2 ± 3.7 years) were asked to serve flat serves to a target zone with maximum speed. With respect to service speed, a significant main effect of condition was found (p < 0.001). Post hoc comparisons revealed faster serves for AF compared to control serves without instruction/feedback (p < 0.01) and compared to EF (p < 0.05), whereas no significant difference was found between EF and IF (p = 0.81). The fastest service speeds were found in the AF condition, whereas the combination of AF + EF did not further promote performance. The number of serves landed in the target zone did not differ between conditions (p = 0.1 7). Thus, no speed-accuracy trade-off was found, indicating that enhanced service speeds did not result in less serves landed in the target zone. Augmented feedback seems most beneficial to instantly enhance tennis serve performance. In contrast to previous studies with recreational sportsmen, EF did not differ from IF, providing further evidence that expertise level and task-relevant instructions mediate the influence of attentional focus on motor performance. [ABSTRACT FROM AUTHOR]

Football academy settings may pose risks to adolescent athletes achieving sufficient sleep because of the contextual challenges these players face (e.g., psychosocial pressure, changes in training, competition, and academic stress). Given the importance of sleep to overall health as well as physical athletic development and injury risk, this study aimed to investigate whether differences in training schedules (morning vs. evening training sessions) affected objective measures of sleep in adolescent academy football (soccer) players. Twelve academy players (mean age 14.18 ± 1.36 years) wore an ActiGraph accelerometer on nights before, and nights of, training days in 2 separate weeks where morning (09:00-11:00 hours) and evening (18:00-20:00 hours) training occurred. Objective sleep parameters and training load data were collected. Night-time sleep periods were categorized as sleep preceding morning training, preceding evening training, or after evening training. One-way univariate and multivariate analyses of variance for repeated measures were performed to determine the impact of the training schedule on sleep. Significance levels were set at p < 0.05. The total sleep time was below the recommended guidelines (<8 hours) across conditions. A large significant effect of the training schedule on time attempted to fall asleep (p = 0.004, effect size [ES] = 0.40) and time of sleep (p = 0.003, ES = 0.41) was present, with post-evening sessions resulting in the latest times. Overall, the players' sleep behavior was resilient to changes in training schedules. However, the low sleep durations (and potential risks to physical performance/injury) suggest that sleep education coupled with practical interventions are required in this cohort. [ABSTRACT FROM AUTHOR]

Brazier, J, Antrobus, M, Stebbings, GK, Day, SH, Callus, P, Erskine, RM, Bennett, MA, Kilduff, LP, and Williams, AG. Anthropometric and physiological characteristics of elite male rugby athletes. J Strength Cond Res 34(6): 1790–1801, 2020 —This is the first article to review the anthropometric and physiological characteristics required for elite rugby performance within both rugby union (RU) and rugby league (RL). Anthropometric characteristics such as height and body mass, and physiological characteristics such as speed and muscular strength, have previously been advocated as key discriminators of playing level within rugby. This review aimed to identify the key anthropometric and physiological properties required for elite performance in rugby, distinguishing between RU and RL, forwards and backs and competitive levels. There are differences between competitive standards such that, at the elite level, athletes are heaviest (RU forwards ~111 kg, backs ~93 kg; RL forwards ~103 kg, backs ~90 kg) with lowest % body fat (RU forwards ~15%, backs ~12%; RL forwards ~14%, backs ~11%), they have most fat-free mass and are strongest (back squat: RU forwards ~176 kg, backs ~157 kg; RL forwards ~188 kg, backs ~168 kg; bench press: RU forwards ~131 kg, backs ~118 kg; RL forwards ~122 kg, backs ~113 kg) and fastest (10 m: RU forwards ~1.87 seconds, backs ~1.77 seconds; 10 m: RL forwards ~1.9 seconds, backs ~1.83 seconds). We also have unpublished data that indicate contemporary RU athletes have less body fat and are stronger and faster than the published data suggest. Regardless, well-developed speed, agility, lower-body power, and strength characteristics are vital for elite performance, probably reflect both environmental (training, diet, etc.) and genetic factors, distinguish between competitive levels, and are therefore important determinants of elite status in rugby. [ABSTRACT FROM AUTHOR]

There is limited information on the risk of eating disorders (EDs) and body image of elite male athletes. However, research studies suggest that there are some athletes who have poor body image and they may be at increased risk of developing EDs. Therefore, the current study investigated risk of EDs, body image, and the relationship with age, in elite rugby union players during their preseason training period. This cross-sectional study was undertaken at the start of the preseason among elite rugby union players in New Zealand. Twenty-six professional rugby union players completed a 49-item questionnaire on body image and disordered eating. A "body image score" was calculated from questionnaire subscales including "drive for thinness," "bulimia," and "body dissatisfaction," with total scores above 20 indicative of poor body image. Body image scores varied from 8 to 39 out of a possible 0-100. Disordered eating behaviors were reported, including binge eating at least once a week (15%, n = 4/26), pathogenic weight control use (4%, n = 1/26), and avoidance of certain foods (77%, n = 20/26). There was a statistically significant inverse association between the bulimia subscale and age (p = 0.034). At the start of the preseason training period, many elite rugby union players experience disturbances in body image. The prevalence of disordered eating behaviors is of concern, and needs to be minimized due to the negative impact on health and performance. A focus on assessment and education of younger male rugby players may be required to reduce disordered eating patterns. [ABSTRACT FROM AUTHOR]

The aim of this study was to describe the effects of 8 weeks of precompetitive preparation period (Pc2P) on the isokinetic muscular characteristics in world-class handball players. Nineteen male professional players (age, 26.6 ± 5.4 years) participated in the study. Two bilateral isokinetic tests of knee joint flexors (H; hamstring) and extensors (Q; quadriceps) were performed before and after Pc2P to determine the peak torque (PT), the mean power (MP), and the ratios (agonist-antagonist, dominant-nondominant, and combined). For the PT, Q at low angular velocity (60°•s) in concentric mode revealed no significant increase for the dominant or nondominant legs. For H, results showed a significant increase for both legs (p < 0.001). At the higher angular velocity (240°•s-1), Q was significantly increased for the dominant (p < 0.005) and nondominant (p < 0.002) legs and also H for both sides (p < 0.001). Eccentric mode (30°•s) showed a significant increase for dominant (p < 0.005) and nondominant (p < 0.01) legs. For MP, results showed significant increase at low angular velocity (p < 0.003) and high angular velocity (p < 0.01) for both legs. In eccentric mode, values showed a significant increase after Pc2P for dominant (p < 0.001) and nondominant (p < 0.02) legs. The ratios showed significant increase for the agonist-antagonist ratio at 60°•s-1 for dominant leg (p < 0.003) and the nondominant leg (p < 0.01). At 240°•s-1, the values showed a significant difference for both side (p < 0.02). From an injury risk perspective, in addition to optimizing performance, these results demonstrated that 8 weeks of Pc2P increased the maximum strength and muscle power of international handball players, even if the ratios of the knee joint muscles did not change during this period. [ABSTRACT FROM AUTHOR]

Walsh, JA, Sanders, D, Hamilton, DL, and Walshe, I. Sleep profiles of elite swimmers during different training phases. J Strength Cond Res 33(3): 811-818, 2019-This study aims to describe the sleeping patterns during different training phases in competitive swimmers. Twelve national- and international-level swimmers (3 females and 9 males) were monitored during 4 different phases, consisting of a preparation training phase, a taper phase, a competition phase, and a rest phase. Sleep parameters were assessed using wrist activity monitors and self-reported sleep diaries. There was a moderately higher (d = 0.70-1.00) sleep onset latency during the competition phase compared with taper, train, and rest phases. Trivial to small differences were observed for total sleep time between phases {d = 0.05-0.40). Sleep efficiency was moderately higher (d = 0.60-0.75) in the training and taper phases compared with competition and rest. Restfulness and fragmentation index (FI) were lowest in the rest with differences between phases being small (d = 0.43-0.51) for restfulness and small to moderate (d = 0.43-0.62) for FI. Time in and out of bed was very largely later (d = 1.96-2.34) in rest compared with the other phases. Total nap time was moderately lower in rest (d= 1.13-1.18) compared with the training and competition phases, whereas there was a small difference (d = 0.46) compared with taper. To conclude, while there were trivial to small differences in sleep quantity between phases, there are small to moderate differences in other sleep parameters. Specifically, sleep onset latency was higher during the competition phase. In addition, this study highlights the substantial between-individual variations in sleep responses during different training phases. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to assess the merit of sports compression socks in minimizing travel-induced performance, physiological, and hematological alterations in elite female volleyball athletes. Twelve elite female volleyballers (age, 25 ± 2 years) traveled from Canberra (Australia) to Manila (Philippines), and were assigned to 1 of 2 conditions; compression socks (COMP, n = 6) worn during travel or a pas¬sive control (CON, n = 6). Dependent measures included countermovement jump (CMJ) performance, subjective ratings of well-being, cardiovascular function, calf girth, and markers of blood clotting, collected before (-24 hours, CMJ; -12 hours, all measures), during (+6.5 and +9 hours, subjective ratings and cardiovascular function), and after (+12 hours, all measures except CMJ; +24 hours and +48 hours, CMJ) travel. When compared with CON, small-to-large effects were observed for COMP to improve heart rate (+9 hours), oxygen saturation (+6.5 hours and +9 hours), alertness (+6.5 hours), fatigue (+6.5 hours), muscle soreness (+6.5 hours and +9 hours), and overall health (+6.5 hours) during travel. After travel, small-to-moderate effects were observed for COMP to improve systolic blood pressure (+12 hours), right calf girth (+12 hours), CMJ height (+24 hours), mean velocity (+24 hours), and relative power (+48 hours), compared with CON. COMP had no effect on the markers of blood clotting. This study suggests that compression socks are beneficial in combating the stressors imposed by long-haul travel in elite athletes, and may have merit for individuals frequenting long-haul travel or competing soon after flying. [ABSTRACT FROM AUTHOR]

11 vs. 11 training games are used to mimic the official match, but differ in playing duration and a consequence of winning or losing. Anxiety levels, crowd pressure, and the intention to win are examples of constraints present in the match, but absent or less prevalent in training. The aim is, therefore, to compare soccer performance in official matches with 11 vs. 11 training games. Six elite youth soccer teams played 5 official matches and 15 training games. Soccer performance, defined as a combination of game characteristics (game duration, transitions, and ball possession duration) and physical (distance covered, high-intensity distance, and sprints), technical (passing), and team tactical performance (inter-team and intra-team distances) and corresponding interaction patterns, was determined with video footage and positional data (local position measurement system). Soccer performance in official matches differed from similar training games, in a way that players covered more distance, sprinted more often, but game pace was lower and players made more mistakes. In addition, team width was smaller and length-per-width ratio larger and teams were tighter coupled in official matches. 11 vs. 11 training games can be used to mimic the match, in particular the team tactical performance. Coaches could increase physical and technical representativeness of training games by raising the stakes and increasing the consequence of winning or losing. [ABSTRACT FROM AUTHOR]

Young, D, Mourot, L, Beato, M, and Coratella, G. The match heart rate and running profile of elite under-21 hurlers during competitive match-play. J Strength Cond Res 32(10): 2925–2933, 2018—The aims of the current study were to examine the physical and physiological demands of elite under-21 male hurling match-play across halves of play and between positions. Global positioning systems (10 Hz) and heart rate (HR) monitors were used to collect data from 95 players during 10 games. Total distance (TD), relative speed, high-speed running (HSR), sprint distance, total sprints, and mean length of sprint was 6,688 ± 942 m, 112 ± 16 m·min−1, 661 ± 203 m, 274 ± 111 m, 18 ± 8 m, and 16 ± 5 m, respectively. Players' mean HR (HRmean) and peak HR (HRpeak) was 165 ± 9 b·min−1 and 190 ± 7 b·min−1, respectively. Decrements in TD (p < 0.05, effect size [ES] = 0.81), HSR (p < 0.05, ES = 0.69), and HRmean (p < 0.05, ES = 0.80) were found between halves. Full backs covered significantly less TD than half backs (p < 0.05, ES = −1.24), midfielders (p < 0.05, ES = −1.39), and half forwards (p < 0.05, ES = −1.85). Half forwards covered a greater TD than full forwards (p < 0.05, ES = 0.94), greater HSR than full backs (p < 0.05, ES = 1.13), and greater sprint distance than half backs (p < 0.05, ES = 1.41). Between-half decreases were evident in TD, HSR, and HRmean, with no significant positional differences observed in TD, HSR, number of sprints, length of sprint, HRpeak, and HRmean between half backs, midfielders, and half forwards. The current findings provide data that coaches should consider to customize training program design for under-21 hurlers. [ABSTRACT FROM AUTHOR]

Duthie, GM, Thornton, HR, Delaney, JA, Connolly, DR, and Serpiello, FR. Running intensities in elite youth soccer by age and position. J Strength Cond Res 32(10): 2918–2924, 2018—The purpose of this investigation was to examine differences between the peak running speed, acceleration, and metabolic power of elite youth soccer across a range of age levels by position. Ninety-six elite junior soccer players were assessed between 2015 and 2017. Ninety-six elite junior soccer players (at time of match: age, 15.8 ± 0.9 years; body mass, 69.1 ± 8.0 kg) were assessed during 61 games within the 2015, 2016, and 2017 season, for a total of 441 individual match observations (4.8 ± 3.3 matches per player, range 1–13). Participants were classified by age group: under 15 (U15, n = 121, 14.7 ± 0.3 years), under 16 (U16, n = 176, 15.8 ± 0.3 years), or under 17 (U17, n = 144, 16.7 ± 0.4 years), and according to their playing position: Attacker (ATT), Defender (DEF), Mid-Fielder (MID), or Wide (WIDE). Participants wore global positioning system units during each match, where speed (m·min−1), acceleration/deceleration (m·s−2), and metabolic power (Pmet) were established. A 1- to 10-minute moving average was applied to establish the intercept (c) and slope (n) of running intensity variables as a power law y = cx n relationship. Linear mixed models were used to examine differences in the intercept and slope between age group and player position. There were no substantial differences in peak (intercept) or decline (slope) in running intensity between playing levels. Several differences were observed in the peak running speeds (m·min−1), particularly peak running speeds of ATT and DEF being substantially lower than the MID. Despite variability between positions, we suggest that the magnitude of these differences would not warrant the prescription of different running intensities across positions at the elite junior level. These findings describe the peak running intensities of elite junior soccer, useful in the monitoring and prescription of training to ensure that players are prepared for the most demanding periods of competition. [ABSTRACT FROM AUTHOR]

Perrotta, AS, White, MD, Koehle, MS, Taunton, JE, and Warburton, DER. Efficacy of hot yoga as a heat stress technique for enhancing plasma volume and cardiovascular performance in elite female field hockey players. J Strength Cond Res 32(10): 2878–2887, 2018—This investigation examined the efficacy of hot yoga as an alternative heat stress technique for enhancing plasma volume percentage (PV%) and cardiovascular performance. Ten international caliber female field hockey players completed six 60-minute hot yoga sessions using permissive dehydration over 6 days, followed by a 6-day national team camp. Changes in PV% were examined throughout the intervention and postintervention period. A graded maximal exercise test was performed in a thermoneutral environment (23.2 ± 1.0° C) 24 hours before and 24 hours after intervention. Six days of hot yoga initiated a moderate state of hypovolemia (PV% = −3.5%, 90% confidence limit [CL] [−6.9 to −0.13]), trivial improvements in maximal aerobic power (V̇ o 2max) (effect size [ES] = 0.06, 90% CL [−0.16 to 0.28]), and run time to exhaustion (ES = 0.11, 90% CL [−0.07 to 0.29]). Small meaningful improvements were observed in running speed (km·h−1) at ventilatory threshold (VT1) (ES = 0.34, 90% CL [−0.08 to 0.76]), VT2 (ES = 0.53, 90% CL [−0.05 to 1.1]), along with adaptations in the respiratory exchange ratio during high-intensity exercise (ES = –0.25, 90% CL [–0.62 to 0.12]). A large plasma volume expansion transpired 72 hours after intervention (PV% = 5.0%, 90% CL [1.3–8.7]) that contracted to a small expansion after 6 days (PV% = 1.6%, 90% CL [−1.0 to 4.2]). This investigation provides practitioners an alternative heat stress technique conducive for team sport, involving minimal exercise stress that can preserve maximal cardiovascular performance over periodized rest weeks within the yearly training plan. Furthermore, improvements in submaximal performance and a delayed hypervolemic response may provide a performance-enhancing effect when entering a 6-day competition period. [ABSTRACT FROM AUTHOR]

This study presents normative values for isokinetic knee extension and flexion muscle strength tests in 350 elite, female, handball (n = 150) and football (n = 200) players. Isokinetic concentric muscle strength tests at 60°⋅sec-1 were recorded bilaterally using a dynamometer. Peak torque (in Newton meter [N⋅m]), body mass normalized peak torque (N⋅m⋅kg-1), and hamstring to quadriceps ratio (H:Q ratio) for dominant and nondominant legs were recorded. The female elite players were 20.9 ± 4.0 years, started playing at the elite level at the age of 18.2 ± 2.7 years, with a mean of 9.7 ± 2.2 hours of weekly in-season training. Handball players demonstrated greater quadriceps muscle strength compared with football players (11.0%) (p < 0.001), also when normalized to body mass (4.1%) (p = 0.012), but not for weight-adjusted hamstring muscle strength. The H:Q ratio was higher on the dominant compared with the nondominant leg for handball players only (p = 0.012). The H:Q ratio was significantly lower for handball players (0.58) compared with football players (0.60) (p < 0.02). These normative values for isokinetic knee extension and flexion torques of healthy, elite, female handball and football players can be used to set rehabilitation goals for muscle strength after injury and enable comparison with uninjured legs. Significantly greater quadriceps muscle strength was found for handball players compared with football players, also when normalized to body mass. [ABSTRACT FROM AUTHOR]

This study aimed to identify the most sensible heart rate-based indices to physical measures of training load and intensity. Twenty professional football players competing in the Russian league and in the UEFA Champions League were monitored during 15 training sessions (270 individual records) using global positioning systems devices (10 Hz) and heart rate telemetry. Expert knowledge and a collinearity r < 0.5 were used initially to select the external physical markers for the final analysis. A multivariate-adjusted within-subjects model was used to quantify the correlations between heart rate indices with various measures of training intensity and load. The number of accelerations >2.5 m⋅s-2 and the number of high-intensity bursts remained in the final multivariate model for training load. The adjusted correlations with Banister's training impulse (TRIMP) were r = 0.49 and r = 0.3, respectively. For training intensity, the same previous variables expressed as per minute plus the volume of high-speed running per minute remained in the final model. The adjusted correlations with the percentage of time spent above 80% of individual maximum heart rate (tHR80%) were, in the same order, r = 0.3, r = 0.22, and r = 0.18. The results of this study demonstrate the validity of TRIMP and tHR80% as measures of training load and intensity, respectively, and identified accelerations and high-intensity repeated efforts (high-intensity bursts) as being moderately predictive of heart rate responses. [ABSTRACT FROM AUTHOR]

The aim of the current investigation was to evaluate the variation in the anthropometric and performance characteristics of elite Gaelic football players with respect to position. One hundred forty-eight elite Gaelic footballers underwent anthropometric (height, body mass, sum of 7 skinfolds, and % adipose tissue) and performance (counter movement jump [CMJ] height, CMJ peak power, CMJ relative peak power, squat jump [SJ] height, SJ peak power, SJ relative peak power, 5-, 10-, and 20-m sprint times, and Yo-Yo Intermittent Recovery Test Level 2 [Yo-YoIRT2]) during "the early in-season" phase. Data were split into 5 positional groups (full back, half back, midfield, half forward, and full forward). Higher adipose tissue percentage estimate was observed in full forwards when compared with the half backs (p = 0.001), midfielders (p = 0.035), and half forwards (p = 0.021). Full forwards had significantly greater SJ (p = 0.036) and CMJ (p = 0.013) when compared with the midfielders with no other positional differences observed. No significant variation in sprint times was observed across the positions. When Yo-YoIRT2 was considered, full forwards and full backs completed significantly lower distances compared with the middle 3 positional lines of half backs, midfielders, and half forwards (p = 0.00). The current study is the first to provide normative data for anthropometric and performance values of elite Gaelic football players which in turn can be used by coaches to generate appropriate training regimes to maximize position-specific preparation for competitive match-play. [ABSTRACT FROM AUTHOR]

This study examined the influence of tactical and situational variables on offensive sequences during elite football matches. A sample of 68 games and 1,694 offensive sequences from the Spanish La Liga, Italian Serie A, German Bundesliga, English Premier League, and Champions League were analyzed using χ² and logistic regression analyses. Results revealed that counterattacks (odds ratio [OR] = 1.44; 95% confidence interval [CI]: 1.13-1.83; p < 0.01) and fast attacks (OR = 1.43; 95% CI: 1.11-1.85; p < 0.01) increased the success of an offensive sequence by 40% compared with positional attacks. The chance of an offensive sequence ending effectively in games from the Spanish, Italian, and English Leagues were higher than that in the Champions League. Offensive sequences that started in the preoffensive or offensive zones were more successful than those started in the defensive zones. An increase of 1 second in the offensive sequence duration and an extra pass resulted in a decrease of 2% (OR = 0.98; 95% CI: 0.98-0.99; p < 0.001) and 7% (OR = 0.93; 95% CI: 0.91--0.96; p < 0.001), respectively, in the probability of its success. These findings could assist coaches in designing specific training situations that improve the effectiveness of the offensive process. [ABSTRACT FROM AUTHOR]

The aims of this study were (a) to analyze anthropometric, physical fitness, and throwing speed in women elite handball players of different ages and (b) to develop a multivariate model explaining handball performance from a multidimensional perspective. Eighty women handball players (18.2 ± 4.0 years in age) from national team selections participated in the study. The players belonged to A Team, under-19, under-17, and under-15 national teams. All were evaluated by basic anthropometry, physical fitness tests, and handball throwing speed. A 1-way analysis of variance was used to establish the differences between teams with a Bonferroni post hoc test. For each team, a discriminant analysis was performed to determine the predictor variables of performance. Pearson's simple correlation coefficients were calculated between each of the variables. The results of this particular study showed that (a) between the A Team and the U19 team, there were only differences in mass, countermovement jump (CMJ), medicine ball throw, and yo-yo test, (b) the A Team and U19 predictive models correctly classified 76 and 90% of the samples, respectively, with the variables involved being mass and body mass index (A Team) and 30-m sprint and 7-m throwing speed (U19 team), and (c) the 7- and 9-m throwing speeds were correlated with each other and with stature, mass, CMJ, and medicine ball throw (0.367 ≤ r ≤ 0.533; 0.001 ≤ p ≤ 0.05). These results could help improve coaches' knowledge of elite female teams, in particular, in the country where the study was conducted and in others of similar characteristics. [ABSTRACT FROM AUTHOR]

Power, as a testing and training metric to quantify effort, is well accepted in cycling, but is not commonly used in running to quantify effort or performance. This study sought to investigate a novel training tool, the Stryd Running Power Meter, and the applicability of running power (and its individually calculated run mechanics) to be a useful surrogate of metabolic demand (V...O2), across different running surfaces, within different caliber runners. Recreational (n = 13) and elite (n = 11) runners completed a test assessing V...O2 at 3 different paces, while wearing a Stryd Power Meter on both an indoor treadmill and an outdoor track, to investigate relationships between estimated running power and metabolic demand. A weak but significant relationship was found between running power and V...O2 considering all participants as a homogenous group (r = 0.29); however, when assessing each population individually, no significant relationship was found. Examination of the individual mechanical components of power revealed that a correlative decrease in V...O2 representing improved efficiency was associated with decreased ground contact time (r = 0.56), vertical oscillation (r = 0.46), and cadence (r = 0.37) on the treadmill in the recreational group only. Although metabolic demand differed significantly between surfaces at most speeds, run power did not accurately reflect differences in metabolic cost between the 2 surfaces. Running power, calculated via the Stryd Power Meter, is not sufficiently accurate as a surrogate of metabolic demand, particularly in the elite population. However, in a recreational population, this training tool could be useful for feedback on several running dynamics known to influence running economy. [ABSTRACT FROM AUTHOR]

Lathlean, TJH, Gastin, PB, Newstead, S, and Finch, CF. Elite junior Australian football players experience significantly different loads across levels of competition and training modes. J Strength Cond Res 32(7): 2031–2038, 2018—Well-developed physical qualities such as high jumping ability, running endurance, acceleration, and speed can help aspiring junior elite Australian football (AF) players transition to the Australian Football League competition. To do so, players need to experience sufficient load to enhance their physical resilience without increasing their risk of negative outcomes in terms of impaired wellness or injury. The aim of this study was to investigate the differences in load for different levels of competition and training modes across one competitive season. Elite junior AF players (n = 562, aged 17.7 ± 0.3, range: 16–18 years) were recruited from 9 teams across the under-18 state league competition in Victoria. All players recorded their training and match intensities according to the session rating of perceived exertion method. Training sessions were categorized according to skills, strength, conditioning, and other activities, whereas matches were identified according to level of competition. The loads in U18 state league matches (656.7 ± 210.9 au) were significantly higher (p = 0.027) than those in school matches (643.3 ± 260.9 au) and those in U18 representative matches (617.2 ± 175.4). Players, who undertook more than one match per week, experienced significantly less load in subsequent matches (p < 0.001). Furthermore, U18 state league training sessions carried the most load when compared with other training modes. This article highlights that different combinations of training and match involvement affect overall player load, which may predispose players to negative outcomes such as impaired wellness or increased injury risk. [ABSTRACT FROM AUTHOR]

Elite swimmers demonstrate faster swimming turn times that are potentially a result of having better strength-power characteristics than subelite swimmers. We quantified differences between dry-land and swimming turn force-time characteristics in elite swimmers and subelite swimmers. Subelite (11 males: 17.4 ± 0.6 years; 10 females: 17.1 ± 0.6 years) and elite swimmers (15 male: 23.2 ± 2.3 years; 7 female: 21.6 ± 2.5 years) were tested in a cross-sectional design. All swimmers performed a body weight and loaded (20 kg females, 30 kg males) squat jump (SJ) on a portable force platform. On the same day, all swimmers completed swimming turn analyses using a force platform fixed within the pool wall. The magnitude of difference between groups was estimated using a standardized mean difference (effect size statistic). Elite male and female swimmers had superior swimming turn and dry-land force-time characteristics to subelite swimmers in all tests. The standardized mean differences between groups ranged from small to very large. The largest differences were SJ peak velocity unloaded (3.07 ± 1.0 m•s-1 males, 3.49 ± 2.29 m•s-1 females; standardized mean difference ± 90% confidence limits) and SJ peak power unloaded (2.59 ± 0.79 w male, 2.80 ± 1.64 w female) with elite male and female swimmers having a ~25-50% higher performance than the subelites in both characteristics. Elite swimmers exhibit superior strength and power characteristics for the swimming turn compared with younger and less experienced swimmers. A well-planned and executed strength and conditioning program is needed for emerging swimmers to develop these qualities, as they transition to senior levels. [ABSTRACT FROM AUTHOR]

Badminton-specific speed and endurance performance was evaluated in both cross-sectional and longitudinal studies of elite youth players and compared with the physiological capacities of world top-50 singles players. The cross-sectional study involved 10 males in the category U15 (<15 years), 10 U17, 9 U19, and 4 senior elite players. They performed 30-m sprint, countermovement jump, and badminton-specific speed (B-SPEED) and endurance (B-ENDURANCE) tests. The longitudinal data were collected for 10 U15 players with 1- and 2-year follow-up measures. Compared with seniors, B-SPEED performance was 20 ± 5% slower for U15 (p < 0.001), 7 ± 3% slower for U17 (p < 0.05), and nonsignificantly slower (3 ± 3%; p = 0.27) for U19. B-ENDURANCE performance was 45 ± 11% shorter for U15 (p < 0.001), 25 ± 7% shorter for U17 (p < 0.001), and 17 ± 10% shorter for U19 (p < 0.01). The longitudinal data for U15 revealed that B-SPEED performance improved from a 19 ± 5% (p < 0.001) deficit at baseline to 5 ± 5% (p = 0.23) at first-year, and 2 ± 3% (p = 0.43) at second-year follow-up. B-ENDURANCE performance improved from a 43 ± 11% deficit at baseline to 27 ± 10 and 17 ± 7% at 1- and 2-year follow-up (p < 0.001), respectively. Countermovement jump also improved with aging from 29 ± 5% deficit for U15 to 13 ± 6% deficit for U19 (p < 0.01). In conclusion, B-SPEED improves markedly with aging in youth elite players to achieve, by age 19, values matching world-class players. Endurance improved markedly, but with a significant deficit remaining in comparison with senior elite players. [ABSTRACT FROM AUTHOR]

The purpose of this study was 2-fold: first, to examine the impact of exercise-induced muscle damage (EIMD) on physical fitness qualities after a basketball-specific training session; second, to determine the reproducibility of the sport-specific performance measures in elite female basketball players. Ten elite female basketball players (age 25.6 ± 4.5 years; height 1.8 ± 0.7 m; and body mass 76.7 ± 8.3 kg) undertook a 90-minute training session involving repeated jumping, sprinting, and game-simulated training. Indirect muscle damage markers (i.e., countermovement jump, delayed onset of muscle soreness [DOMS], and creatine kinase [CK]) and sport-specific performances (i.e., change-of-direction [COD] test and suicide test [ST]) were measured before and 24 hours after training. These measures were also collected 1 week after training to determine the reproducibility of the basketball-specific performance measures. A significant reduction in lower-body power (-3.5 ± 3.6%; p ≤ 0.05), while a significant increase in DOMS (46.7 ± 26.3%; p ≤ 0.05) and CK (57.6 ± 23.1%; p ≤ 0.05) was observed 24 hours after exercise. The ST was also significantly increased (2.1 ± 1.8%; p ≤ 0.05), although no difference was observed for COD (0.1 ± 2.0%; p > 0.05). The intraclass correlation coefficient and coefficient of variation for the COD and ST were 0.81 and 0.90, respectively, and 1.9 and 1.5%, respectively. In conclusion, appropriate recovery should be considered the day after basketball-specific training sessions in elite basketball players. Furthermore, this study showed the usability of performance measures to detect changes during periods of EIMD, with acceptable reproducibility and minimal measurement error. [ABSTRACT FROM AUTHOR]

In addition to technical, tactical, and psychological skills, performance in playing basketball depends on anthropometry and physical fitness. However, limited information is available regarding such features in women. We hypothesized that anthropometry and physical fitness are associated with female basketball performance, and consequently, performance could be predicted using the results of certain anthropometric measures and fitness tests. Body parameters (age, height, body mass, skinfold thicknesses, limb perimeters, and lengths) were measured. Physical fitness capacities (jumping, agility with and without the ball, and speed) were measured by specific tests. In addition, game performance was assessed using technical statistics (rebounds, assists, and points) and the performance index rating (PIR). Teams ranked better in the regular season had smaller mean fat skinfold thickness and spent less time in the agility tests (T-Drill). Correlation analyses indicated that players with better PIR were older, taller, and had a longer arm span and greater contracted arm perimeter (CAP). Furthermore, those players had better results in the T-Drill test. Multiple regression analysis indicated that combined age, height, CAP, fat skinfold thickness, and time in T-Drill test yielded a strong predictor of PIR per time played. In conclusion, the results of the present study indicate that some anthropometric and physical fitness characteristics of female elite basketball teams and players are highly associated with performance-related parameters. In addition, a regression model has been developed to predict the performance of female basketball players. [ABSTRACT FROM AUTHOR]

This study aims to quantify and compare the positional game demands of international junior and senior rugby league competition for the first time. Global positioning system (GPS) and video analysis were used to track 118 elite male rugby league players (57 seniors aged 28.7 ± 4.4 years; 61 juniors aged 17.2 ± 0.5 years) over 10 international matches (6 senior; 4 junior) characterized as either forwards (n = 67) or backs (n = 51). There were significant increases in the offensive carries (0.18 cf. 0.09 n·min; r = 0.56) and defensive tackles (0.36 cf. 0.23 n·min; r = 0.3) between senior and junior players, and forwards and backs (0.16 cf. 0.09; r = 0.34 and 0.41 cf. 0.14; r = 0.52), respectively. Running demands were significantly greater in backs than forwards (independent of playing level) for total distance (6,962 ± 1,263 m cf. 4,879 ± 1,824 m; r = 0.55), individualized high-speed distances (310 ± 158 m cf. 250 ± 171 m; r = 0.2), high-intensity accelerations (28.7 ± 12.1 m·s-1 cf. 21.9 ± 11.7 m·s-1; r = 0.27), and decelerations (57.2 ± 18.3 m·s-1 cf. 43.0 ± 17.8 m·s-1; r = 0.38). Positional differences were eliminated when reported relative to minutes played. From a practical perspective, although running demands relative to time on the pitch may prepare junior players for senior competition, it is not representative of the increased body mass and contact frequency within the senior game. Coaches should therefore reflect these differences within their physical preparation programs to prepare junior athletes accordingly for progression to the senior level. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of the use of a 2-week precooling strategy and supplementation coenzyme Q10 (CoQ10) on superoxide dismutase (SOD), catalase (CAT), and serum glutathione peroxidase (GPx) in elite, adolescent swimmers during heavy and regular trainings and recording of free-style swimming. Thirty-six healthy males (mean ± SD; age: 17.5 ± 1.1 years, body fat content: 14.55 ± 1.75%) were randomly selected and divided into 4 groups of CoQ10 (300 mg⋅d-1), precooling (immersion in the water at 18 ± 0.5° C), supplementation with precooling, and control, each with 9 participants. During an 18-session protocol in the morning and evening, participants attended speed and endurance trainings for 5 km every session. A 3-stage blood sampling was conducted before the first recording and before and after the second recording in 800, 200, and 50 m. Repeated measurement and the Bonferroni correction were used for the statistical analyses of the data (α = 0.05). According to the results, there was no significant difference between the mean serum level of SOD, CAT, and GPx in the groups at the first stage of blood sampling (p > 0.05). At the third stage, a significant difference was observed among all groups (p < 0.05). At the second stage, precooling and control groups show a significant increase compared with the supplementation and supplementation with precooling groups (p < 0.05). As an antioxidant essential for adenosine triphosphate synthesis, CoQ10 supplementation prevented adverse changes of antioxidant enzymes during heavy trainings and swimming recording and decreased the serum level, while precooling individually increased serum level of antioxidant enzymes by itself. [ABSTRACT FROM AUTHOR]

The aim of this study was to quantify the mean weekly training load (TL) of elite adolescent rugby union players participating in multiple teams and examine the differences between playing positions. Twenty elite male adolescent rugby union players (17.4 ± 0.7 years) were recruited from a regional academy and categorized by playing position: forwards (n = 10) and backs (n = 10). Global positioning system and accelerometer microtechnology was used to quantify external TL, and session rating of perceived exertion (sRPE) was used to quantify internal TL during all sessions throughout a 10-week in-season period. A total of 97 complete observations (5 ± 3 weeks per participant) were analyzed, and differences between positions were assessed using Cohen's d effect sizes (ES) and magnitude-based inferences. Mean weekly sRPE was 1,217 6 364 arbitrary units (AU) (between-subject coefficient of variation [CV] = 30%), with a total distance (TD) of 11,629 6 3,445 m (CV = 30%), and PlayerLoad (PL) of 1,124 ± 330 AU (CV = 29%). Within-subject CV ranged between 5 and 78% for sRPE, 24 and 82% for TD, and 19 and 84% for PL. Mean TD (13,063 ± 3,933 vs. 10,195 ± 2,242 m) and PL (1,246 ± 345 vs. 1,002 ± 279 AU) were both likely greater for backs compared with forwards (moderate ES); however, differences in sRPE were unclear (small ES). Although mean internal TLs and volumes were low, external TLs were higher than previously reported during preseason and in-season periods in senior professional players. Additionally, the large between-subject and within-subject variation in weekly TL suggests that players participate in a chaotic training system. [ABSTRACT FROM AUTHOR]

The aim of the current investigation was to understand the impact of pretraining neuromuscular performance and creatine kinase (CK) status on subsequent training performance in elite soccer players. Thirty soccer players (age: 25.3 ± 3.1 years; height: 183 ± 7 cm; mass: 72 ± 7 kg) were involved in this observational study. Each morning before training, players completed assessments for neuromuscular performance (countermovement jump; CMJ) and CK levels. Global positioning technology provided external load: total distance, high-speed distance, sprint distance, accelerations, decelerations, average metabolic power, explosive distance, and high metabolic power distance (.25.5⋅kg-1). Mixed-effect linear models revealed significant effects for CK and CMJ Z-score on total high-speed distance, very high-speed distance, accelerations, decelerations, explosive distance, and maximal velocity. Effects are reported with 90% confidence limits. A CK Z-score of +1 corresponded to a 25.5 ± 1.1, 23.9 ± 0.5, 24.3 6 2.9%, 24.1 ± 2.9%, 23.1 ± 2.9%, and 24.6 ± 1.9%, reduction in total high-speed distance, very high-speed distance, accelerations, decelerations, explosive distance, and maximal velocity, respectively. Countermovement jump Z-score of 21 corresponded to a 23.5 ± 1.1, 22.9 ± 0.5, 22.1 ± 1.4, 25.3 6 2.9%, 23.8 ± 2.9%, 21.1 ± 2.9%, and 25.6 ± 1.2% reduction in these external load measures. Magnitude-based analysis revealed that the practical size of the effect of a pretraining CMJ Z-score of 21 and CK Z-score of +1 would have on total high-speed distance, very high-speed distance, high metabolic power distance (.25.5 ⋅kg-1), accelerations, decelerations, explosive distance, and maximal velocity was likely negative. The results of this study suggest that systematic pretraining monitoring of neuromuscular and muscle stress within soccer cohorts can provide coaches with information about the training output that can be expected from individual players during a training session. [ABSTRACT FROM AUTHOR]

Few data exist that assess athlete tracking and monitoring for the development of strategies to optimize performance and reduce fatigue in elite athletes. The purpose of the present study was to assess the efficacy of external load and internal stress monitoring as assessment tools for examining a performance index of fatigue. A retrospective analysis was performed on data collected over the course of the preseason in 10 elite male NCAA Division 1 basketball players. Internal stress was assessed using Omegawave Technology readiness scores and compared with the performance index of countermovement jump (CMJ). The external load that accumulated during the previous practice, quantified by PlayerLoad (PL; Catapult), was compared with CMJ values and Omegawave scores. The results indicated that high, compared to low CNS Omegawave Readiness Scores (6.7 ± 05.1, 4.5 ± 1.2 AU; p < 0.001), were associated with increased CMJ (62.1 ± 6.5 vs. 59.4 ± 6.6 cm; p = 0.05), Power (6,590 ± 526.7 vs. 6,383.5 ± 606.8 W; p = 0.05), Omegawave Overall Readiness (5.8 ± 1.1 vs. 5.0 ± 0.7 AU; p = 0.05), and Omega Potential (Omega) (21.3 ± 6.3 vs. 9.9 ± 20.8 mV; p = 0.07). An increased PL during the previous exposure was associated with decreased CMJ (58.7 ± 4.7 cm vs. 60.4 ± 5.1 cm; p < 0.001) and increased TRIMP (135.1 ± 35.9 vs. 65.6 ± 20.0 AU; p < 0.001), and duration (115.4 ± 27.1 vs. 65.56 ± 20.0 minutes; p = < 0.001) despite no differences in Omegawave CNS Readiness scores. We conclude that Omegawave and Catapult technologies provide independent information related to performance and may be effective tools for monitoring athlete performance. [ABSTRACT FROM AUTHOR]

We examined high-intensity activities in a top-class ice-hockey game and the effect of training status. Male ice-hockey players (n = 36) from the National Hockey League participated. Match analysis was performed during a game and physical capacity was assessed by a sub- maximal Yo-Yo Intermittent Recovery Ice-hockey test, level 1 (YYIR1-IHSUB). Venous blood samples were collected 24-hour post-game to determine markers of muscle damage. Players performed 119 ± 8 and 31 ± 3m⋅min-1 of high intensity and sprint skating, respectively, during a game. Total distance covered was 4,606 ± 219 m (2,260-6,749 m), of which high-intensity distance was 2042 ± 97 m (757-3,026 m). Sprint-skating speed was 5-8% higher (p ≤ 0.05) in periods 1 and 2 vs. period 3 and overtime. Defensemen (D) covered 29% more (p ≤ 0.05) skating in total than forwards (F) and were on the ice 47% longer. However, F performed 54% more (p ≤ 0.05) high-intensity skating per minute than defensemen. Plasma creatine kinase (CK) was 338 ± 45 (78-757) U⋅L-1 24-hour post-game. Heart rate loading during YYIR1-IHSUB correlated inversely (p ≤ 0.05) to the frequency of high-intensity skating bouts (r = 20.55) and ...O2max (r = 20.85) and positively to post-game CK (r =0.49; p ≤ 0.05). In conclusion, ice hockey is a multiple-sprint sport that provokes fatigue in the latter half of a game. Forwards perform more intense skating than defense-men. Moreover, high-intensity game activities during top-class ice hockey are correlated with cardiovascular loading during a submaximal skating test. Taken together, training of elite ice-hockey players should improve the ability for repeated high-intensity skating, and testing should include the YYIR1-IHSUB test as an indicator for ice-hockey-specific physical match performance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate differences among player positions at 3 grade levels in elite, collegiate-prospective American football players. Participants' data (n = 7,160) were analyzed for this study (mean height [Ht] ± SD = 178 ± 7 cm, mass [Bm] = 86 ± 19 kg). Data were obtained from 12 different high school American football recruiting combines hosted by Zybek Sports (Boulder, Colorado). Eight 2-way (9 x 3) mixed factorial analysis of variances {position (defensive back [DB], defensive end, defensive lineman, linebacker, offensive lineman [OL], quarterback, running back, tight end, and wide receiver [WR]) x grade (freshmen, sophomores, and juniors)} were used to test for differences among the mean test scores for each combine measure (Ht, Bm, 40-yard [40 yd] dash, proagility [PA] drill, L-cone [LC] drill, vertical jump [VJ], and broad jump [BJ]). There were position-related differences (p ≤ 0.05) for Ht, 40 yd dash, and BJ, within each grade level and for Bm, PA, LC, and VJ independent of grade level. Generally, the results showed that OL were the tallest, weighed the most, and exhibited the lowest performance scores among positions. Running backs were the shortest, whereas DBs and WRs weighed the least and exhibited the highest performance scores among positions. These results demonstrate the value of classifying high school--aged American football players according to their specific position rather than categorical groupings such as "line" vs. "skill" vs. "big skill" when evaluating anthropometric and athletic performance combine test results. [ABSTRACT FROM AUTHOR]

There is a substantial amount of research on the responses to isometric and eccentric loading. However, only a paucity of literature exists on the responses to isoinertial loading, especially in trained athletic populations using realistic loading protocols. The purpose of this study was to examine the acute neuromuscular response to a bout of isoinertial resistance loading in elite rugby players. Seventeen male (age: 19.5 ± 2.3 years) rugby union players performed a conventional maximal isoinertial resistance loading protocol. Countermovement jump (CMJ) and maximal voluntary isometric contraction (MVC) squat performance were measured on 3 occasions: at baseline, immediately post, and 48 hour post. The results indicated that the decrease in MVC (9.7%) is greater than or comparable with the CMJ output variables (4.2-10.3%), immediately postexercise. Although isometric strength had demonstrated a full recovery at 48 hour post, many of the key CMJ output variables were still impaired (p ≤ 0.05). Similar findings were observed in the normalized CMJ curves. Complete recovery of the ability to rapidly produced force may require more than 48 hours in many athletes. Individual responses should, therefore, be monitored to help plan acute and chronic training loads. It is recommended that future fatigue studies should incorporate temporal phase analyses to consider the power-, force-, velocity-, and displacement-time curves. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the effects of a 5-week neuromuscular training (NMT) implemented before or after a tennis session in prepubertal players on selected components of physical fitness. Sixteen high-level tennis players with a mean age of 12.9 ± 0.4 years participated in this study, and were assigned to either a training group performing NMT before tennis-specific training (BT; n = 8) or a group that conducted NMT after tennis-specific training (AT; n = 8). Pretest and posttest included: speed (5, 10, and 20 m); modified 5-0-5 agility test; countermovement jump (CMJ); overhead medicine ball throw (MBT); and serve velocity (SV). Results showed that the BT group achieved positive effects from pretest to posttest measures in speed (d = 0.52, 0.32, and 1.08 for 5, 10, and 20 m respectively), 5-0-5 (d = 0.22), CMJ (d = 0.29), MBT (d = 0.51), and SV (d = 0.32), whereas trivial (10 m, 20 m, CMJ, SV, and MBT) or negative effects (d = -0.19 and -0.24 for 5 m and 5-0-5, respectively) were reported for the AT group. The inclusion of an NMT session before the regular tennis training led to positive effects from pretest to posttest measures in performance-related variables (i.e., jump, sprint, change of direction capacity, as well as upper-body power), whereas conducting the same exercise sessions after the regular tennis training was not accompanied by the same improvements. [ABSTRACT FROM AUTHOR]

The use of global positioning system (GPS) technology in Gaelic football is the primary source of quantifying game demands. The aim of this study was to quantify the acceleration profile of elite Gaelic football. Thirty-six elite male Gaelic football players (mean ± SD, age: 24 ± 6 years; height: 180 ± 7 cm; mass: 81 ± 7 kg) across 5 playing positions took part in a multiple study (n = 154 observations). Player movement was recorded during 19 (n = 19) competitive games over 2 seasons using 4-Hz GPS (VXSport, New Zealand). The average total distance (m), high-speed running distance (m; ≥17 km•h-1), and very high-speed running distance (m; ≥22 km•h-1) were recorded. In addition, the number (n), distance (m), and the duration of accelerations were quantified. Accelerations were subdivided into 14 equal parts of 5-minute epochs (E1 = 0-5 minutes, E2 = 5-10 minutes, E3 = 10-15 minutes etc). Players performed 166 ± 41 accelerations. High-speed running distance and very high-speed running distance was 1563 ± 605 and 524 ± 190 m, respectively. The mean acceleration distance was 267 ± 45 m distributed between 12 ± 5 accelerations per 5-minute epoch. The maximum acceleration epoch classified as the greatest distance covered accelerating during a predetermined 5-minute epoch was 296 ± 134 m. The PEAK epoch resulted in a significant reduction of acceleration distance covered in the period before and in the subsequent epoch. An understanding of the acceleration profile in Gaelic football can inform the prescription of appropriate training regimen. [ABSTRACT FROM AUTHOR]

This study describes the global work-rate of elite hurling match-play and the influence which positional difference has on work-rate is considered. The movement of ninety-four players was recorded using global positioning system, sampling at 4 Hz in a total of 12 games. Data were classified according to the positional line on the field and period of the match. The total and high-speed distance of match-play was 7,617 ± 1,219 m (95% confidence interval [CI], 7,367-7,866) and 1,134 ± 358 m (95% CI, 1,060-1,206), respectively. The maximum speed attained was 29.8 ± 2.3 km•h-1 with a mean speed of 6.1 ± 1 km•h. The second {271 ± 107 m (p = 0.001; effect size [ES] = 0.25)}, third (278 ± 118 m [p = 0.001; ES = 0.21]), and fourth quarter (255 ± 108 m [p = 0.001; ES = 0.31]) high-speed running distance differed significantly from that of the first quarter (330 ± 120 m). There was a significant difference in total (p = 0.001; ES = 0.01-0.85), high-speed running (p = 0.001; ES = 0.21-0.76), and sprint (p = 0.013; ES = 0.01-0.39) distance across the positions, with midfielders undertaking the highest volume of work, followed by the half-forward and half-back lines and finally the full-forward and full-back lines. A decrease in high-speed running distance seems to occur through out the game and in particular at the latter stages of each half. Distinct positional work profiles are evident. The present finding provide a context on which training which replicates the work-rate of match-play may be formulated, thus helping to improve the physical preparation of elite players. [ABSTRACT FROM AUTHOR]