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Background/Objectives: Aviation firefighting is a strenuous occupation that requires individuals to engage in intense physical activity amidst elevated stress levels and extreme environmental conditions. Despite this, there has been limited investigation regarding the internal and external loads associated with aviation firefighting tasks, which include hose dragging, stair climbing, casualty evacuation, and fire extinguishing in airports and aircrafts. The aim of this study was to examine the internal and external loads placed on aviation firefighters. By identifying these demands, this study seeks to inform the development of targeted training strategies, improve job safety, and lower the risk of musculoskeletal injuries. Methods: Sixteen Australian aviation firefighters (35.13 ± 8.2 years) were recruited and assigned specific roles to complete an aircraft firefighting scenario. Measures of heart rate (HR), oxygen consumption ( V ˙ O2), and rating of perceived exertion (RPE) were used to quantify internal load, while measures of completion time and distance travelled were used to quantify external load. Results: The median scenario completion time was 21 min (IQR = 5), with each role travelling a median distance of 245–541 m. During the scenario, median average HR values ranged between 61.1 and 72.0% HRmax and median maximal HR values ranged between 77.8 and 84.4% HRmax. As the only group to record V ˙ O2, driver firefighters operated at a median average V ˙ O2 of 49% of their V ˙ O2max and achieved a median maximal V ˙ O2 of 78% of their V ˙ O2max. Conclusions: This study effectively identified the task-specific internal and external loads associated with aviation firefighting, offering valuable insights for developing specific training protocols for firefighters to ensure appropriate physical capacity to perform their job roles safely. [ABSTRACT FROM AUTHOR]

Purpose: To determine the impact of the quality and quantity of sleep during an international flight on subsequent objective sleep characteristics, training and match-day load, self-reported well-being, and perceptions of jet lag of elite female cricketers during an International Cricket Council Women's T20 World Cup. Methods: In-flight and tournament objective sleep characteristics of 11 elite female cricketers were assessed using activity monitors. Seated in business class, players traveled west from Melbourne, Australia, to Chennai, India. The outbound flight departed Melbourne at 3:30 AM with a stopover in Dubai for 2 hours. The arrival time in Chennai was 8:10 PM local time (1:40 AM in Melbourne). The total travel time was 19 hours 35 minutes. Perceptual ratings of jet lag, well-being, and training and competition load were collected. To determine the impact of in-flight sleep on tournament measures, a median split was used to create subsamples based on (1) in-flight sleep quantity and (2) in-flight sleep quality (2 groups: higher vs lower). Spearman correlation coefficients were calculated to assess the bivariate associations between sleep measures, self-reported well-being, perceptual measures of jet lag, and internal training and match-day load. Results: Mean duration and efficiency of in-flight sleep bouts were 4.72 hours and 87.45%, respectively. Aggregated in-flight sleep duration was 14.64 + 3.56 hours. Players with higher in-flight sleep efficiency reported higher ratings for fatigue (ie, lower perceived fatigue) during the tournament period. Tournament sleep duration was longer, and bed and wake times were earlier compared with habitual. Compared with other nights during the tournament, sleep duration was shorter following matches. Conclusions: Maximizing in-flight sleep quality and quantity appears to have implications for recovery and sleep exhibited during competition. Sleep duration was longer than habitual except for the night of a match, which suggests that T20 matches may disrupt sleep duration. [ABSTRACT FROM AUTHOR]

Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Chalkley, D, Cole, MH, Johnston, RD, and Cormack, SJ. Validity and reliability of thoracic-mounted inertial measurement units to derive gait characteristics during running. J Strength Cond Res 38(2): 274-282, 2024--Inertial measurement units (IMUs) attached to the tibia or lumbar spine can be used to analyze running gait but, with teamsports, are often contained in global navigation satellite system (GNSS) units worn on the thoracic spine. We assessed the validity and reliability of thoracic-mounted IMUs to derive gait characteristics, including peak vertical ground reaction force (vGRFpeak) and vertical stiffness (Kvert). Sixteen recreationally active subjects performed 40 m run throughs at 3-4, 5-6, and 7-8 m·s21. Inertial measurement units were attached to the tibia, lumbar, and thoracic spine, whereas 2 GNSS units were also worn on the thoracic spine. Initial contact (IC) from a validated algorithm was evaluated with F1 score and agreement (mean difference 6SD) of gait data with the tibia and lumbar spine using nonparametric limits of agreement (LoA). Test-retest error {coefficient of variation, CV (95% confidence interval [CI])} established reliability. Thoracic IMUs detected a nearly perfect proportion (F1 $ 0.95) of IC events compared with tibia and lumbar sites. Step length had the strongest agreement (0 6 0.04 m) at 3-4 m·s21, whereas contact time improved from 3 to 4 (20.02860.018 second) to 7-8m·s21 (20.00460.013 second). All values for Kvert fell within the LoA at 7-8 m·s21. Test-retest error was #12.8% for all gait characteristics obtained from GNSS units, where Kvert was most reliable at 3-4 m·s21 (6.8% [5.2, 9.6]) and vGRFpeak at 7-8m·s21 (3.7% [2.5, 5.2]). The thoracic-spine site is suitable to derive gait characteristics, including Kvert, from IMUs within GNSS units, eliminating the need for additional sensors to analyze running gait. [ABSTRACT FROM AUTHOR]

Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Johnston, RD, and Cormack, SJ. Thoracic-worn accelerometers detect fatiguerelated changes in vertical stiffness during sprinting. J Strength Cond Res 38(2): 283-289, 2024--Thoracic-mounted accelerometers are valid and reliable for analyzing gait characteristics and may provide the opportunity to assess running-related neuromuscular fatigue (NMF) during training and competition without the need for additional tests, such as a countermovement jump (CMJ). However, their sensitivity for detecting fatigue-related changes in gait across different speeds is unclear. We, therefore, assessed the changes in accelerometer-derived gait characteristics, including vertical stiffness (Kvert), following a repeated sprint protocol (RSP). Sixteen recreationally active subjects performed single and repeated CMJs on a force plate and 40 m run throughs overground at 3-4, 5-6, and 7-8 m·s21 pre-post a 123 40 mRSP. Gait characteristics (contact time, step frequency, step length, Kvert, etc.) were derived from an accelerometer contained within a global navigation satellite system unit on the thoracic spine using a validated algorithm. Changes in running gait and CMJ performance were assessed using a linear mixed-effects model (95% confidence interval [95% CI]; effect size [ES]). Significance was set at p < 0.05. A significant reduction in Kvert occurred at 7-8m·s21 following the RSP (28.51 kN·m21 [213.9, 23.11]; p 5 0.007; ES [95% CI] 5 20.39 [20.62, 20.15]) which coincided with a decreased jump height (20.03 m [20.04, 20.01]; p 5 0.002; ES [95% CI] 5 20.87 [21.41, 20.30]). However, all other gait characteristics were not significantly different irrespective of speed. Thoracic-worn accelerometers can detect changes in Kvert at 7-8 m·s21 which may be useful for monitoring NMF during sprinting. However, a RSP does not result in altered gait mechanics in subsequent running at lower speeds. [ABSTRACT FROM AUTHOR]

Purpose: To assess relationships between objective sleep characteristics, external training loads, and subjective ratings of well-being in elite Australian football (AF) players. Methods: A total of 38 elite male AF players recorded objective sleep characteristics over a 15-day period using an activity monitor. External load was assessed during main field sessions, and ratings of well-being were provided each morning. Canonical correlation analysis was used to create canonical dimensions for each variable set (sleep, well-being, and external load). Relationships between dimensions representing sleep, external load, and well-being were quantified using Pearson r. Results: Canonical correlations were moderate between pretraining sleep and external training load (r = .32-.49), pretraining sleep and well-being (r = .32), and well-being and postlraining sleep {r=. 36). Moderate to strong correlations were observed between dimensions representing external training load and posttraining sleep (r= .31-.67), and well-being and external training load (r = .32-67). Player load and Player load 2D (PL2D) showed the greatest association to pretraining and posttraining objective sleep characteristics and well-being. Fragmented sleep was associated with players completing the following training with a higher PL2D. Conclusions: Maximum speed, player load, and PL2D were the common associations between objective sleep characteristics and well-being in AF players. Improving pretraining sleep quality and quantity may have a positive impact on AF players' well-being and movement strategy during field sessions. Following training sessions that have high maximum speed and PL2D, the increased requirement for sleep should be considered by ensuring that subsequent sessions do not start earlier than required. [ABSTRACT FROM AUTHOR]

Purpose: To assess and compare the validity of internal and external Australian football (AF) training-load measures for predicting preseason variation of match-play exercise intensity (MEI sim/min) using a variable dose–response model. Methods: A total of 21 professional male AF players completed an 18-wk preseason macrocycle. Preseason internal training load was quntified using the session rating-of-perceived-exertion method (sRPE) and external load from satellite (as distance [Dist] and high-speed distance [HS Dist]) and accelerometer (Player Load [PL]) data. Using a training-impulse (TRIMPs) calculation, external load expressed in arbitrary units was represented as TRIMPsDist, TRIMPsHSDist, and TRIMPsPL. Preseason training load and MEI sim/min data were applied to a variable dose–response model, which provided estimates of MEI sim/min. Model estimates of MEI sim/min were correlated with actual measures from each match-play drill performed during the preseason macrocycle. Magnitude-based inferences (effect size [90% confidence interval]) were calculated to determine practical differences in the precision of MEI sim/min estimates using each of the internal- and external-load inputs. Results: Estimates of MEI sim/min demonstrated very large and large associations with actual MEI sim/min with models constructed from external and internal training inputs (r [90% confidence interval]; TRIMPsDist.73 [.72–.74], TRIMPsPL.72 [.71–.73], and sRPESkills.67 [.56–.78]). There were trivial differences in the precision of MEI sim/min estimates between models constructed from TRIMPsDist and TRIMPsPL and between internal input methods. Conclusions: Variable dose-response models from multiple training-load inputs can predict the within-individual variation of MEI sim/min across an entire preseason macrocycle. Models informed by external training inputs (TRIMPsDist and TRIMPsPL) exhibited predictive power comparable to those of sRPESkills models. [ABSTRACT FROM AUTHOR]

Purpose: To assess and compare the validity of internal and external Australian football (AF) training-load measures for predicting match exercise intensity (MEI/min) and player-rank score (PRScore) using a variable dose-response model. Methods: A cohort of 25 professional AF players (23 ± 3 y, 188.3 ± 7.2 cm, 87.7 ± 8.4 kg) completed a 24-wk in-season macrocycle. In-season internal training and match load were quantified using session rating of perceived exertion (sRPE) and external load from satellite and accelerometer data. Using a training-impulse (TRIMP) calculation, external load (au) was represented as distance (TRIMPDist), distance ≥4.16 m/s (TRIMPHSDist), and PlayerLoad (TRIMPPL). In-season training load, MEI/min, and PRScore were applied to a variable dose-response model, which provided estimates of MEI/min and PRScore. Predicted MEI/min and PRScore were correlated with actual measures from each match. The magnitude of the difference between MEI/min and PRScore estimates for each model input and the difference between the precision of internal and external load measures to predict MEI/min and PRScore were calculated using the effect size ± 90% confidence interval (CI). Results: Estimates of MEI/min demonstrated very large associations with actual MEI/min (r, 90% CI) (eg, TRIMPDist .76 ± .13, and sRPESkills .73 ± .14). Estimates of PRScore demonstrated associations of large magnitude with actual PRScore using the same inputs. Precision of actual MEI/min was lowest using sRPE compared with (ES ± 90% CI) TRIMPDist, -.67 ± .34, and TRIMPPL, -.91 ± .39. There were trivial and unclear differences in the precision of PRScore estimates between TRIMP and sRPE inputs. Conclusions: Dose-response models from multiple training-load inputs can predict within-individual variation of MEI/min and PRScore. Internal and external training-input methods exhibited comparable predictive power. [ABSTRACT FROM AUTHOR]

Measuring and tracking performance variables such as peak power output is essential for assessing the effects of training and for informing adjustments to optimize program design. The purpose of this study was to track the long-term changes in muscular power, velocity, and jump height of elite Australian Rules Football (ARF) players during a 3-year period. Twelve members of an ARF team were tracked during the study. The physical characteristics of the subjects were age, 25.3 [+ or -] 2.8 years; body mass, 93.0 [+ or -] 6.8 kg; and height, 192 [+ or -] 6 cm. The subjects performed unweighted and weighted (40 kg) countermovement jumps (CMJ) and static jumps (SJ). Peak power, jump height, and bar velocity were determined using a force plate and position transducer. Measures of peak power output during both the CMJ and SJ indicated significant (p [less than or equal to] 0.001) increases of 13% (effect size [ES] = 0.70) and 17% (ES = 1.77), respectively, during the course of the tracking period. There was also a significant 9% (ES = 0.71) increase in CMJ40 peak power. The subjects' CMJ peak velocity improved by 10.7% (ES = 0.34), and SJ peak velocity improved by 12.6% (ES = 0.37). The data from this study show that elite-level ARF players can continue to increase muscular power and velocity. This information is of interest to strength and conditioning coaches who are interested in improving power performance of their athletes for a long-term period. Key Words jump squat, assessment, velocity, training

The purpose of this research project was to evaluate the methodology of an iso-inertial force-velocity assessment utilizing a range of loads and a group of high-performance athletes. A total of 26 subjects (19.8 [+ or -] 2.6 years, 196.3 [+ or -] 9.6 cm, 88.6 [+ or -] 8.9 kg) participated in this study. Interday reliability of various force-time measures obtained during the performance of countermovement jumps with a range of loads was examined, followed by a validity assessment of the various measures' ability to discriminate among performance levels, while the ability of the test protocol to detect training-induced changes was assessed by comparing results before and after an intensive 12-week training period. Force and velocity variables were observed to be reliable (intraclass correlation coefficient 0.74-0.99). Large effect size statistic (ES > 0.50) differences among player groups were observed for peak power (1.36-2.25), relative peak power (1.57-2.42), and peak force (0.74-0.95). Significant (p < 0.05) and large (ES > 0.50) improvements were observed in the kinetic values after the intensive training period. The results of this study indicate that the incremental load power profile is an acceptably reliable, valid, and sensitive method of assessing force and power capabilities of the leg extensors in high-performance and elite volleyball players. KEY WORDS assessment, jump squat, volleyball, football

Purpose: To assess the impact of match-start time and days relative to match compared with the habitual sleep characteristics of elite Australian Football (AF) players. Methods: 45 elite male AF players were assessed during the preseason (habitual) and across 4 home matches during the season. Players wore an activity monitor the night before (-1), night of (0), 1 night after (+1), and 2 nights (+2) after each match and completed a self-reported rating of sleep quality. A 2-way ANOVA with Tukey post hoc was used to determine differences in sleep characteristics between match-start times and days relative to the match. Two-way nested ANOVA was conducted to examine differences between competition and habitual phases. Effect size ± 90% confidence interval (ES ± 90% CI) was calculated to quantify the magnitude of pairwise differences. Results: Differences observed in sleep-onset latency (ES = 0.11 ± 0.16), sleep rating (ES = 0.08 ± 0.14), and sleep duration (ES = 0.08 ± 0.01) between competition and habitual periods were trivial. Sleep efficiency was almost certainly higher during competition than habitual, but this was not reflected in the subjective rating of sleep quality. Conclusions: Elite AF competition does not cause substantial disruption to sleep characteristics compared with habitual sleep. While match-start time has some impact on sleep variables, it appears that the match itself is more of a disruption than the start time. Subjective ratings of sleep from well-being questionnaires appear limited in their ability to accurately provide an indication of sleep quality. [ABSTRACT FROM AUTHOR]

Objective measures of recovery from football match play could be useful for assessing athletes' readiness to train, if sensitive to preceding match load. Purpose: To identify the sensitivity of countermovement-jump (CMJ) performance and concentration of salivary testosterone and cortisol relative to elite football match load. Methods: CMJ performance and salivary hormones were measured in 18 elite football players before (27, 1 h) and after (0.5, 18, 42, 66, 90 h) 3 consecutive matches. Match load was determined via accelerometer-derived PlayerLoad and divided into tertiles. Sensitivity of CMJ performance and hormone concentrations to match load was quantified with t statistics and magnitude-based inferences (change in mean as % ± 90% confidence interval) derived with a linear mixed model. Results: Jump height was reduced in medium and high load at 0.5 h (10% ± 7% and 16% ± 8%) and 18 h (7% ± 4% and 9% ± 5%) postmatch. There was a 12% ± 7% reduction in ratio of flight time to contraction time (FT:CT) in high load at 0.5 h post, with reductions in medium and high load at 18 h. Reductions in FT:CT persisted at later postmatch time points than changes in jump height. Increased cortisol (range 55--165%) and testosterone (range 17--20%) were observed in all match loads at 0.5 h post, with individual variability thereafter. Conclusions: Measures of CMJ performance and hormonal concentrations were sensitive to levels of A League football match load. Although jump height was reduced immediately postmatch, FT:CT provided a more sensitive measure of recovery. Football match play induces an acute hormonal response with substantial individual variability thereafter. [ABSTRACT FROM AUTHOR]

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 reduced on days 3 to 4 (-0.37 ± 0.51) compared with day 1. RPE did not differ and total points played only declined on day 3 (-0.38 ± 1.02). Postmatch 20-m sprint (0.79 ± 0.77) and prematch CMJ (-0.43 ± 0.27) performance declined on days 2 to 4 compared with prematch day 1. Although serve velocity was maintained, compromised postmatch serve accuracy was evident compared with prematch day 1 (0.52 ± 0.58). CK increased each day, as did ratings of muscle soreness and fatigue. Conclusions: Players reduced external physical loads, through declines in movement, over 4 consecutive days of prolonged competitive tennis. This may be affected by tactical changes and pacing strategies. Alongside this, impairments in sprinting and jumping ability, perceptual and biochemical markers of muscle damage, and reduced mood states may be a function of neuromuscular and perceptual fatigue. [ABSTRACT FROM AUTHOR]

To determine differences in load/min (AU) between standards of netball match play. Methods: Load/ min (AU) representing accumulated accelerations measured by triaxial accelerometers was recorded during matches of 2 higher- and 2 lower-standard teams (N = 32 players). Differences in load/min (AU) were compared within and between standards for playing position and periods of play. Differences were considered meaningful if there was >75% likelihood of exceeding a small (0.2) effect size. Results: Mean (± SD) full-match load/min (AU) for the higher and lower standards were 9.96 ± 2.50 and 6.88 ± 1.88, respectively (100% likely lower). The higher standard had greater (mean 97% likely) load/min (AU) values in each position. The difference between 1st and 2nd halves’ load/min (AU) was unclear at the higher standard, while lower-grade centers had a lower (–7.7% ± 10.8%, 81% likely) load/min (AU) in the 2nd half and in all quarters compared with the 1st. There was little intrastandard variation in individual vector contributions to load/min (AU); however, higher-standard players accumulated a greater proportion of the total in the vertical plane (mean 93% likely). Conclusions: Higher-standard players produced greater load/min (AU) than their lower-standard counterparts in all positions. Playing standard influenced the pattern of load/min (AU) accumulation across a match, and individual vector analysis suggests that different-standard players have dissimilar movement characteristics. Load/min (AU) appears to be a useful method for assessing activity profile in netball. [ABSTRACT FROM AUTHOR]

Purpose: To determine the impact of neuromuscular fatigue (NMF) assessed from variables obtained during a countermovement jump on exercise intensity measured with triaxial accelerometers (load per minute [LPM]) and the association between LPM and measures of running activity in elite Australian Football. Methods: Seventeen elite Australian Football players performed the Yo-Yo Intermittent Recovery Test level 2 (Yo-Yo IR2) and provided a baseline measure of NMF (flight timexontraction time [FT:CT]) from a countermovement jump before the season. Weekly samples of FT:CT, coaches' rating of performance (votes), LPM, and percent contribution of the 3 vectors from the accelerometers in addition to high-speed-running meters per minute at >15 km/hand total distance relative to playing time (m/min) from matches were collected. Samples were divided into fatigued and nonfatigued groups based on reductions in FT:CT. Percent contributions of vectors to LPM were assessed to determine the likelihood of a meaningful difference between fatigued and nonfatigued groups. Pearson correlations were calculated to determine relationships between accelerometer vectors and running variables, votes, and Yo-Yo IR2 score. Results: Fatigue reduced the contribution of the vertical vector by (mean ± 90% CI) -5.8% ±6.1% (86% likely) and the number of practically important correlations. Conclusions: NMF affects the contribution of individual vectors to total LPM, with a likely tendency toward more running at low speed and less acceleration. Fatigue appears to limit the influence of the aerobic and anaerobic qualities assessed via the Yo-Yo IR2 test on LPM and seems implicated in pacing. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine if Yo-Yo Intermittent Recovery level 2 (Yo-Yo IR2) and the number of interchange rotations affected the match activity profile of elite Australian footballers. Method: Fifteen elite Australian footballers completed the Yo-Yo IR2 before the beginning of the season and played across 22 matches in which match activity profiles were measured via microtechnology devices containing a global positioning system (GPS) and accelerometer. An interchange rotation was counted when a player left the field and was replaced with another player. Yo-Yo IR2 results were further split into high and low groups. Results: Players match speed decreased from 1st to 4th quarter, while average-speed (m/min: P - .05) and low-speed activity (LSA, <15 km/h) per minute (LSA m/min; P - .06) significantly decreased in the 2nd half. Yo-Yo IR2 influenced the amount of m/min, high-speed running (HSR, >15 km/h) per minute (HSR m/min) and accelerometer load/min throughout the entire match. The number of interchanges significantly influenced the HSR m/min and m/min throughout the match except in the 2nd quarter. Furthermore, the low Yo-Yo IR2 group had significantly less LSA m/min in the 4th quarter than the high Yo-Yo IR2 group (92.2 vs 96.7 m/ min, P = .06). Conclusions: Both the Yo-Yo IR2 and number of interchanges contribute to m/min and HSR m/min produced by elite Australian footballers, affecting their match activity. However, while it appears that improved Yo-Yo IR2 performance prevents reductions in LSA m/min during a match, higher-speed activities (HSR m/min) and overall physical activity (m/min and load/min) are still reduced in the 4th quarter compared with the 1 st quarter. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the influence of multiple games on exercise intensity during a world-class hockey tournament. Methods: 15 players (mean ± SD age 27 ± 4 y, stature 179 ± 5 cm, body mass 77 ± 5 kg, and estimated VO2 64.2 ± 3.1 mL - kg-1 - min-1) competing in the Champions Trophy (CT). Global-positioning systems assessed total distance (TD), low-speed activity (LSA; 0.10-4.17 m/s), and high-speed running (HSR; >4.17 m/s) distance. Differences in movement demands (TD, LSA, HSR) between positions and matches were assessed using the effect size and percent difference ± 90% confidence intervals. Two levels of comparison were made. First, data from subsequent matches were compared with match 1, and, second, data from each match compared with a tournament average (TA). Results: In all matches, compared with game 1, midfielders performed less HSR distance. However, the amount of HSR did not decrease as the tournament progressed. When compared with the TA, defenders showed more variation in each match. All positions showed lower movement outputs when the team won by a large margin. Conclusions: It was possible for elite team-sport athletes to maintain exercise intensity when playing 6 matches in a period of 9 days, contrary to the only other investigation of this in elite male field hockey. [ABSTRACT FROM AUTHOR]

Purpose: The main purpose of this study was to determine the relationships between countermovement jump {CM)) variables and acceleration and maximum speed performance. Methods: Twenty-three elite Australian football players were tested on a CMJ. which yielded several kinematic and kinetic variables describing leg muscle function. A 40 m sprint was also conducted to assess acceleration (10 m time) and an estimate of maximum speed (flying 20 m time). Players from one Australian Football League (AFL) club were tested and Pearson correlations for CMJ variables and sprint performance were calculated. Results: Jump height, peak velocity, peak force, and peak power had less than 50% common variance, and therefore represented independent expressions of CMJ performance. Generally. the correlations between CMJ variables and sprinting performance were stronger for maximum speed (small to large effect sizes) than for acceleration (trivial to moderate sizes). The variable that produced the strongest correlation with acceleration was jump height (r = -0.430. P = .041 ) and with maximum speed was peak power/weight (r = -0.649, P = .001 ). Conclusions: The results indicate that if an integrated system comprising a position transducer and a force platform is available for CMJ assessment, jump height and peak power/weight are useful variables to describe leg muscle explosive function for athletes who perform sprints. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to examine the changes in neuromuscular, perceptual and hormonal measures following professional rugby league matches during different length between-match microcycles. Methods: Twelve professional rugby league players from the same team were assessed for changes in countermovement jump (CMJ) performance (flight time and relative power), perceptual responses (fatigue, well-being and muscle soreness) and salivary hormone (testosterone [T] and cortisol [C]) levels during 5, 7 and 9 d between-match training microcycles. All training was prescribed by the club coaches and was monitored using the session-RPE method. Results: Lower mean daily training load was completed on the 5 d compared with the 7 and 9 d microcycles. CMJ flight time and relative power, perception of fatigue, overall well-being and muscle soreness were significantly reduced in the 48 h following the match in each microcycle (P < .05). Most CMJ variables returned to near baseline values following 4 d in each microcycle. Countermovement jump relative power was lower in the 7 d microcycle in comparison with the 9 d microcycle (P < .05). There was increased fatigue at 48 h in the 7 and 9 d microcycles (P < .05) but had returned to baseline in the 5 d microcycle. Salivary T and C did not change in response to the match. Discussion: Neuromuscular performance and perception of fatigue are reduced for at least 48 h following a rugby league match but can be recovered to baseline levels within 4 d. These findings show that with appropriate training, it is possible to recover neuromuscular and perceptual measures within 4 d after a rugby league match. [ABSTRACT FROM AUTHOR]