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Background: Professional rugby union is a high-intensity contact sport with position-specific high training and match volumes across a season that may lead to periods of fatigue if above a typically experienced threshold. This study assesses the influence of match play and/or training on fatigue levels in rugby union players. Objective: We aimed to perform a systematic review and meta-analysis of measures used to assess fatigue status in male professional rugby union players. Methods: Using electronic databases (PubMed, SPORTDiscus, Web of Science, Cochrane Library, EMBASE, and MEDLINE), a systematic review of fatigue testing in rugby union was conducted on (1) neuromuscular, (2) subjective self-report, (3) biochemical, and (4) heart rate-derived measures. Results: Thirty-seven articles were included in this systematic review, of which 14 were further included in a meta-analysis. The results of the meta-analysis revealed small, yet not significant, decreases in countermovement jump height immediately after (effect size [ES] = − 0.29; 95% confidence interval [CI] − 0.64 to 0.06), 24 h (ES = − 0.43; 95% CI − 3.99 to 3.21), and 48 h (ES = − 0.22; 95% CI − 0.47 to 0.02) after exposure to rugby union match play or training. Reported wellness (ES = − 0.33; 95% CI − 1.70 to 1.04) and tiredness (ES = − 0.14; 95% CI − 1.30 to 1.03) declined over a period of a few weeks (however, the results were not-statistically significant), meanwhile muscle soreness increased (ES = 0.91; 95% CI 0.06 to 1.75) within the 96 h after the exposure to rugby union match play or training. Finally, while cortisol levels (ES = 1.87; 95% CI − 1.54 to 5.29) increased, testosterone declined (ES = − 1.54; 95% CI − 7.16 to 4.08) within the 24 h after the exposure. However, these results were not statistically significant. Conclusions: Subjective measures of muscle soreness can be used to assess fatigue after match play and training in rugby union players. Within-study and between-study variability for countermovement jump height, biochemical markers, and heart rate-derived measures means the utility (practical application) of these measures to assess fatigue in professional rugby union players after matches and training is unclear. Clinical Trial Registration: PROSPERO ID: CRD42020216706. [ABSTRACT FROM AUTHOR]

The current study performed a series of online focus groups to understand elite rugby league players' experiences of collision. Eighteen rugby league players comprising different playing positions from four teams were recruited to participate in a series of online focus groups, via the Microsoft Team's platform, facilitated by a moderator. Players were competing in Europe's elite rugby league competition, the European Super League (ESL), during the 2021 season. All focus group data were transcribed, coded and analysed using reflexive thematic analysis guide to ensure robust exploring, interpreting and reporting through pattern-based analysis. The findings are split into five key themes: 1) the three-man tackle – the perceived optimal defensive strategy with simultaneous contact, 2) not all collisions are the same; matchplay events change the collision intensity, 3) bracing and blindsiding – two factors that influence experiences of collision and concussion, 4) coaching philosophies and orientations, 5) psychological readiness for collision. Collision sports have an inherent risk of injury; however, in some players' subjective experiences, there are collision types that have a greater association with risk or intensity (blind-sided collisions or long closing distances). It is essential that future research comprehends the effects of these collision types and the further themes. [ABSTRACT FROM AUTHOR]

Purpose: To identify the association between several contextual match factors, technical performance, and external movement demands on the subjective task load of elite rugby league players. Methods: Individual subjective task load, quantified using the National Aeronautics and Space Administration Task Load Index (NASA-TLX), was collected from 29 professional rugby league players from one club competing in the European Super League throughout the 2017 season. The sample consisted of 26 matches (441 individual data points). Linear mixed modeling revealed that various combinations of contextual factors, technical performance, and movement demands were associated with subjective task load. Results: Greater number of tackles (effect size correlation ± 90% confidence intervals; η2 =.18 ±.11), errors (η2 =.15 ±.08), decelerations (η2 =.12 ±.08), increased sprint distance (η2 =.13 ±.08), losing matches (η2 =.36 ±.08), and increased perception of effort (η2 =.27 ±.08) led to most likely–very likely increases in subjective total task load. The independent variables included in the final model for subjective mental demand (match outcome, time played, and number of accelerations) were unclear, excluding a likely small correlation with technical errors (η2 =.10 ±.08). Conclusions: These data provide a greater understanding of the subjective task load and their association with several contextual factors, technical performance, and external movement demands during rugby league competition. Practitioners could use this detailed quantification of internal loads to inform recovery sessions and current training practices. [ABSTRACT FROM AUTHOR]

Purpose: To examine responses to a simulated rugby league protocol designed to include more stochastic commands, and therefore require greater vigilance, than traditional team-sport simulation protocols. Methods: Eleven male university rugby players completed 2 trials (randomized and control [CON]) of a rugby league movement simulation protocol, separated by 7 to 10 d. The CON trial consisted of 48 repeated ∼115-s cycles of activity. The stochastic simulation (STOCH) was matched for the number and types of activity performed every 5.45 min in CON but included no repeated cycles of activity. Movement using GPS, heart rate, rating of perceived exertion, and Stroop test performance was assessed throughout. Maximum voluntary contraction peak torque, voluntary activation (in percentage), and global task load were assessed after exercise. Results: The mean mental demand of STOCH was higher than CON (effect size [ES] = 0.56; ±0.69). Mean sprint speed was higher in STOCH (22.5 [1.4] vs 21.6 [1.6] km·h−1, ES = 0.50; ±0.55), which was accompanied by a higher rating of perceived exertion (14.3 [1.0] vs 13.0 [1.4], ES = 0.87; ±0.67) and a greater number of errors in the Stroop test (10.3 [2.5] vs 9.3 [1.4] errors; ES = 0.65; ±0.83). Maximum voluntary contraction peak torque (CON = −48.4 [31.6] N·m and STOCH = −39.6 [36.6] N·m) and voluntary activation (CON = −8.3% [4.8%] and STOCH = −6.0% [4.1%]) was similarly reduced in both trials. Conclusions: Providing more stochastic commands, which requires greater vigilance, might alter performance and associated physiological, perceptual, and cognitive responses to team-sport simulations. [ABSTRACT FROM AUTHOR]

Purpose: To examine the within- and between-sexes physical performance, well-being, and neuromuscular function responses across a 4-day international touch rugby (Touch) tournament. Methods: Twenty-one males and 20 females completed measures of well-being (fatigue, soreness, sleep, mood, and stress) and neuromuscular function (countermovement jump height, peak power output, and peak force) during a 4-day tournament with internal, external, and perceptual loads recorded for all matches. Results: Relative and absolute total, low-intensity (females), and high-intensity distance were lower on day 3 (males and females) (effect size [ES] = −0.37 to −0.71) compared with day 1. Mean heart rate was possibly to most likely lower during the tournament (except day 2 males; ES = −0.36 to −0.74), whereas rating of perceived exertion-training load was consistently higher in females (ES = 0.02 to 0.83). The change in mean fatigue, soreness, and overall well-being was unclear to most likely lower (ES = −0.33 to −1.90) across the tournament for both sexes, with greater perceived fatigue and soreness in females on days 3 to 4 (ES = 0.39 to 0.78). Jump height and peak power output were possibly to most likely lower across days 2 to 4 (ES = −0.30 to −0.84), with greater reductions in females (ES = 0.21 to 0.66). Well-being, countermovement jump height, and peak force were associated with changes in external, internal, and perceptual measures of load across the tournament (η2 = −.37 to.39). Conclusions: Elite Touch players experience reductions in well-being, neuromuscular function, and running performance across a 4-day tournament, with notable differences in fatigue and running between males and females, suggesting that sex-specific monitoring and intervention strategies are necessary. [ABSTRACT FROM AUTHOR]

Purpose: To determine the utility of running-only and rugby-specific, in-season sprint interval interventions in professional rugby league players. Methods: Thirty-one professional academy rugby players were assigned to a rugby-specific (SITr/s, n = 16) or running-only (SITr, n = 15) sprint interval training group. Measures of speed, power, change of direction ability, prone Yo-Yo Intermittent Recovery Test (Yo-Yo IR1) performance, and heart rate recovery were taken before and after the 2-week intervention as were submaximal responses to the prone Yo-Yo IR1. Internal, external, and perceptual responses were collected during SITr/s and SITr, with well-being and neuromuscular function assessed before each session. Results: Despite contrasting (possible to most likely) internal, external, and perceptual responses to the SIT interventions, possible to most likely within-group improvements in physical characteristics, heart rate recovery, and submaximal responses to the prone Yo-Yo IR1 were observed after both interventions. Between-group analysis favored the SITr/s intervention (trivial to moderate) for changes in 10-m sprint time, countermovement jump, change of direction, and medicine ball throw as well as submaximal (280–440 m) high metabolic power, PlayerLoad™, and acceleration distance during the prone Yo-Yo IR1. Overall changes in well-being or neuromuscular function were unclear. Conclusions: Two weeks of SITr/s and SITr were effective for improving physical characteristics, heart rate recovery, and submaximal responses to the prone Yo-Yo IR1, with no clear change in well-being and neuromuscular function. Between-group analysis favored the SITr/s group, suggesting that the inclusion of sport-specific actions should be considered for in-season conditioning of rugby league players. [ABSTRACT FROM AUTHOR]

Purpose: To assess whether a standardized testing battery can differentiate anthropometric and physical qualities between youth, academy, and senior rugby league players and determine the discriminant validity of the battery. Methods: A total of 729 rugby league players from multiple clubs in England categorized as youth (n = 235), academy (n = 362), and senior (n = 132) players completed a standardized testing battery that included the assessment of anthropometric and physical characteristics during preseason. Data were analyzed using magnitude-based inferences and discriminant analysis. Results: Academy players were most likely taller and heavier than youth players (effect size [ES] =0.64-1.21), with possibly to most likely superior countermovement jump, medicine-ball throw, and prone Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance (ES = 0.23-1.00). Senior players were likely to most likely taller and heavier (ES = 0.32-1.84), with possibly to most likely superior 10- and 20-m sprint times, countermovement jump, change of direction, medicine-ball throw, and prone Yo-Yo IR1 than youth and academy players (ES = -0.60 to 2.06). The magnitude of difference appeared to be influenced by playing position. For the most part, the battery possessed discriminant validity with an accuracy of 72.2%. Conclusion: The standardized testing battery differentiates anthropometric and physical qualities of youth, academy, and senior players as a group and, in most instances, within positional groups. Furthermore, the battery is able to discriminate between playing standards with good accuracy and might be included in future assessments and rugby league talent identification. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the factors affecting the anthropometric and physical characteristics of elite academy rugby league players. Methods: One hundred ninety-seven elite academy rugby league players (age = 17.3 [1.0] y) from 5 Super League clubs completed measures of anthropometric and physical characteristics during a competitive season. The interaction between and influence of contextual factors on characteristics was assessed using linear mixed modeling. Results: All physical characteristics improved during preseason and continued to improve until midseason, whereafter 10-m sprint (η² = .20 cf .25), countermovement jump (CMJ) (η² - .28 cf .30), and prone Yo-Yo Intermittent Recovery (Yo-Yo IR) test (η² = .22 cf .54) performance declined. Second (η² = .17) and third (η² = .16) year players were heavier than first-years, whereas third-years had slower 10-m sprint times (η² = .22). Large positional variability was observed for body mass, 20-m sprint time, medicine-ball throw, CMJ, and prone Yo-Yo IR1. Compared with bottom-ranked teams, top-ranked teams demonstrated superior 20-m (η² = -.22) and prone Yo-Yo IR1 (η² = .26) performance, whereas middle-ranked teams reported higher CMJ height (η² = .26) and prone Yo-Yo IR1 distance (η² = .20) but slower 20-m sprint limes (η² = .20). Conclusion: These findings offer practitioners who design training programs for academy rugby league players insight into the relationships between anthropometric and physical characteristics and how they are influenced by playing year, league ranking, position, and season phase. [ABSTRACT FROM AUTHOR]

Purpose: To assess the reliability and external validity of a rugby league movement-simulation protocol for interchange players (RLMSP-i) that was adapted to include physical contact between participants. Methods: A total of 18 rugby players performed 2 trials of a modified RLMSP-i, 7 d apart. The simulation was conducted outdoors on artificial turf with movement speeds controlled using an audio signal. Microtechnology was used to measure locomotive and accelerometer (ie, PlayerLoad™) metrics for both bouts (∼23 min each) alongside heart rate (HR) and rating of perceived exertion (RPE). Results: Reported for each bout, total distance (102 [3] m·min−1 and 101 [3] m·min−1), low-speed distance (77 [3] m·min−1 and 79 [4] m·min−1), high-speed distance (25 [3] m·min−1 and 22 [4] m·min−1), PlayerLoad (10 [1] AU·min−1 and 10 [1] AU·min−1), PlayerLoad slow (3.2 [0.6] AU·min−1 and 3.2 [0.6] AU·min−1), 2-dimensional PlayerLoad (6.0 [0.9] AU·min−1 and 5.7 [0.8] AU·min−1), and HR (86 [5]%HRmax and 84 [6]%HRmax) were similar to match play. The coefficient of variation (CV%) for locomotive metrics ranged from 1.3% to 14.4%, accelerometer CV% 4.4% to 10.0%, and internal load 4.8% to 13.7%. All variables presented a CV% less than the calculated moderate change during 1 or both bouts of the simulation except high-speed distance, percentage of the participant's peak HR, and RPE. Conclusion: The modified RLMSP-i offers a reliable simulation to investigate influences of training and nutrition interventions on the movement and collision activities of rugby league interchange players. [ABSTRACT FROM AUTHOR]

Purpose: To examine the criterion and construct validity of an isometric midthigh-pull dynamometer to assess whole-body strength in professional rugby league players. Methods: Fifty-six male rugby league players (33 senior and 23 youth players) performed 4 isometric midthigh-pull efforts (ie, 2 on the dynamometer and 2 on the force platform) in a randomized and counterbalanced order. Results: Isometric peak force was underestimated (P < .05) using the dynamometer compared with the force platform (95% LoA: -213.5 ± 342.6 N). Linear regression showed that peak force derived from the dynamometer explained 85% (adjusted R² = .85, SEE = 173 N) of the variance in the dependent variable, with the following prediction equation derived: predicted peak force = [1.046 x dynamometer peak force] + 117.594. Cross-validation revealed a nonsignificant bias (P > .05) between the predicted and peak force from the force platform and an adjusted R² (79.6%) that represented shrinkage of 0.4% relative to the cross-validation model (80%). Peak force was greater for the senior than the youth professionals using the dynamometer (2261.2 ± 222 cf 1725.1 ± 298.0 N, respectively; P < .05). Conclusion: The isometric midthigh pull assessed using a dynamometer underestimates criterion peak force but is capable of distinguishing muscle-function characteristics between professional rugby league players of different standards. [ABSTRACT FROM AUTHOR]

This study assessed energy intake and expenditure of international female touch players during an international tournament. Energy intake (food diary) and expenditure (accelerometer, global positioning system) were recorded for 16 female touch players during a four-day tournament, competing in 8.0 ± 1.0 matches; two on Days 1, 2, and 4, and three on Day 3. Total daily energy expenditure (43.6 ± 3.1 Kcal⋅kg-1 body mass (BM)) was not different (p > .05) from energy intake (39.9 ± 9.4 Kcal⋅kg-1 BM). Carbohydrate intakes were below current recommendations (6-10 g⋅kg-1 BM) on Days 1 (4.4 ± 0.6 g⋅kg-1 BM) and 3 (4.7 ± 1.0 g⋅kg-1 BM) and significantly below (p < .05) on Day 2 (4.1 ± 1.0 g⋅kg-1 BM). Protein and fat intakes were consistent with recommendations (protein, 1.2-2.0 g⋅kg-1 BM: fat, 20-35% total Kcal) across Days 1-3 (protein, 1.9 ± 0.8, 2.2 ± 0.8, and 2.0 ± 0.7 g⋅kg-1 BM; fat, 35.6 ± 6.8, 38.5 ± 6.4, and 35.9 ± 5.4% total Kcal). Saturated fat intakes were greater (p < .05) than recommendations (10% total Kcal) on Days 1-3 (12.4 ± 2.9, 14.2 ± 5.1, and 12.7 ± 3.5% total Kcal). On average, female touch players maintained energy balance. Carbohydrate intakes appeared insufficient and might have contributed to the reduction (p < .05) in high-intensity running on Day 3. Further research might investigate the applicability of current nutrition recommendations and the role of carbohydrate in multimatch, multiday tournaments. [ABSTRACT FROM AUTHOR]

Purpose: To examine the influence of knowledge of exercise duration on pacing and performance during simulated rugby league match play. Methods: Thirteen male university rugby players completed 3 simulated rugby league matches (RLMSP-i) on separate days in a random order. In a control trial, participants were informed that they would be performing 2 x 23-min bouts (separated by 20 min) of the RLMSP-i (CON). In a second trial, participants were informed that they would be performing 1 x 23-min bout of the protocol but were then asked to perform another 23-min bout (DEC). In a third trial, participants were not informed of the exercise duration and performed 2 x 23-min bouts (UN). Results: Distance covered and high-intensity running were higher in CON (4813 ± 167 m, 26 ± 4.1 m/min) than DEC (4764 ± 112 m, 25.2 ± 2.8 m/min) and UN (4744 ± 131 m, 24.4 m/min). Compared with CON, high-intensity running and peak speed were typically higher for DEC in bout 1 and lower in bout 2 of the RLMSP-i, while UN was generally lower throughout. Similarly, DEC resulted in an increased heart rate, blood lactate, and rating of perceived exertion than CON in bout 1, whereas these variables were lower throughout the protocol in UN. Conclusions: Pacing and performance during simulated rugby league match play depend on an accurate understanding of the exercise endpoint. Applied practitioners should consider informing players of their likely exercise duration to maximize running. [ABSTRACT FROM AUTHOR]

Player loads and fatigue responses are reported in 15 professional rugby league players (24.3 ± 3.8 y) during a period of intensified fixtures. Repeated measures of internal and external loads, perceived well-being, and jump flight time were recorded across 22 d, comprising 9 training sessions and matches on days 5, 12, 15, and 21 (player exposure: 3.6 ± 0.6 matches). Mean training loads (session rating of perceived exertion x duration) between matches were 1177, 1083, 103, and 650 AU. Relative distance in match 1 (82 m/min) and match 4 (79 m/min) was very likely lower in match 2 (76 m/min) and likely higher in match 3 (86 m/min). High-intensity running (≥5.5 m/s) was likely to very likely lower than match 1 (5 m/min) in matches 2-4 (2, 4, and 3 m/min, respectively). Low-intensity activity was likely to very likely lower than match 1 (78 m/min) in match 2 (74 m/min) and match 4 (73 m/min) but likely higher in match 3 (81 m/min). Accumulated accelerometer loads for matches 1-4 were 384, 473, 373, and 391 AU, respectively. Perceived well-being returned to baseline values (~21 AU) before all matches but was very likely to most likely lower the day after each match (~17 AU). Prematch jump flight times were likely to most likely lower across the period, with mean values of 0.66, 0.65, 0.62, and 0.64 s before matches 1-4, respectively. Across a 22-d cycle with fixture congestion, professional rugby league players experience cumulative neuromuscular fatigue and impaired match running performance. [ABSTRACT FROM AUTHOR]

This aim of this study was to examine the validity of energy expenditure derived from microtechnology when measured during a repeated-effort rugby protocol. Sixteen male rugby players completed a repeated-effort protocol comprising 3 sets of 6 collisions during which movement activity and energy expenditure (EEGPS) were measured using microtechnology. In addition, energy expenditure was estimated from open-circuit spirometry (EEVO2). While related (r = .63, 90%CI .08-.89), there was a systematic underestimation of energy expenditure during the protocol (-5.94 ± 0.67 kcal/min) for EEGPS (7.2 ± 1.0 kcal/min) compared with EEVO2 (13.2 ± 2.3 kcal/min). High-speed-running distance (r = .50, 95%CI -.66 to .84) was related to EEVO2, while PlayerLoad was not (r = .37, 95%CI -.81 to .68). While metabolic power might provide a different measure of external load than other typically used microtechnology metrics (eg, high-speed running, PlayerLoad), it underestimates energy expenditure during intermittent team sports that involve collisions. [ABSTRACT FROM AUTHOR]

Rugby League is a high-intensity collision sport competed over 80 min. Training loads are monitored to maximize recovery and assist in the design of nutritional strategies although no data are available on the total energy expenditure (TEE) of players. We therefore assessed resting metabolic rate (RMR) and TEE in six Super League players over 2 consecutive weeks in-season including one game per week. Fasted RMR was assessed followed by a baseline urine sample before oral administration of a bolus dose of hydrogen (deuterium ²H) and oxygen (18O) stable isotopes in the form of water (²H218O). Every 24 hr thereafter, players provided urine for analysis of TEE via DLW method. Individual training load was quantified using session rating of perceived exertion (sRPE) and data were analyzed using magnitude-based inferences. There were unclear differences in RMR between forwards and backs (7.7 ± 0.5 cf. 8.0 ± 0.3 MJ, respectively). Indirect calorimetry produced RMR values most likely lower than predictive equations (7.9 ± 0.4 cf. 9.2 ± 0.4 MJ, respectively). A most likely increase in TEE from Week 1 to 2 was observed ( 17.9 ± 2.1 cf. 24.2 ± 3.4 MJ) explained by a most likely increase in weekly sRPE (432 ± 19 cf. 555 ± 22 AU), respectively. The difference in TEE between forward and backs was unclear (21.6 ± 4.2 cf. 20.5 ± 4.9 MJ, respectively). We report greater TEE than previously reported in rugby that could be explained by the ability of DLW to account for all match and training-related activities that contributes to TEE. [ABSTRACT FROM AUTHOR]

Purpose: While exercise-induced muscle damage (EIMD) after rugby league match play has been well documented, the specific match actions that contribute to EIMD are unclear. Accordingly, the purpose of this study was to investigate the positional demands of elite rugby league matches and examine their relationship with subsequent EIMD. Methods: Twenty-eight performances (from 17 participants) were captured using 10-Hz global positioning systems over 4 competitive matches. Upper- and lower-body neuromuscular fatigue, creatine kinase (CK), and perceived muscle soreness were assessed 24 h before and at 12, 36, and 60 h after matches. Results: High-intensity running was moderately higher in backs (6.6 ± 2.6 m/min) than in forwards (5.1 ±1.6 m/min), whereas total collisions were moderately lower (31.1 ± 13.1 vs 54.1 ± 37.0). Duration (r = .90, CI: .77-.96) and total (r = .86, CI: .70-.95) and high-intensity distance covered (r = .76, CI: .51-.91) were associated (P < .05) with increased CK concentration postmatch. Total collisions and repeated high-intensity efforts were associated (P < .05) with large decrements in upper-body neuromuscular performance (r = -.48, CI: -.74 to .02; r = -.49, CI: -.77 to .05, respectively), muscle soreness (r = -.68, CI: -.87 to -.10, r = -.66, CI: -.89 to .21, respectively), and CK concentration (r = .67, CI: .42-.85; r = .73, CI: .51-.87, respectively). All EIMD markers returned to baseline within 60 h. Conclusion: Match duration, high-intensity running, and collisions were associated with variations in EIMD markers, suggesting that recovery is dependent on individual match demands. [ABSTRACT FROM AUTHOR]

It is important to understand the extent to which physical contact changes the internal and external load during rugby simulations that aim to replicate the demands of match play. Accordingly, this study examined the role of physical contact on the physiological and perceptual demands during and immediately after a simulated rugby league match. Nineteen male rugby players completed a contact (CON) and a noncontact (NCON) version of the rugby league match-simulation protocol in a randomized crossover design with 1 wk between trials. Relative distance covered (ES = 1.27; ±0.29), low-intensity activity (ES = 1.13; ±0.31), high-intensity running (ES = 0.49; ±0.34), heart rate (ES = 0.52; ±0.35), blood lactate concentration (ES = 0.78; ±0.34), rating of perceived exertion (RPE) (ES = 0.72; ±0.38), and session RPE (ES = 1.45; ±0.51) were all higher in the CON than in the NCON trial. However, peak speeds were lower in the CON trial (ES = -0.99; ±0.40) despite unclear reductions in knee-extensor (ES = 0.19; ±0.40) and -flexor (ES = 0.07; ±0.43) torque. Muscle soreness was also greater after CON than in the NCON trial (ES = 0.97; ±0.55). The addition of physical contact to the movement demands of a simulated rugby league match increases many of the external and internal demands but also results in players' slowing their peak running speed during sprints. These findings highlight the importance of including contacts in simulation protocols and training practices designed to replicate the demands of real match play. [ABSTRACT FROM AUTHOR]

This study examined using passive heat maintenance (PHM) to maintain core temperature after a warm-up and its effect on simulated first half running performance in rugby players. Thirteen male rugby players completed this randomized crossover study. Tympanic temperature was taken before a warm-up and then after a further 15 minutes of passive recovery either with (PHM) or without (CON) a PHM garment. Subjects then completed 23 minutes of the rugby league movement simulation protocol (RLMSP-i). Differences in tympanic temperature were unclear between CON and PHM before (35.7 ± 1.3 cf. 36.0 ± 1.18 C; effect size [ES] = 0.20) and during exercise (34.5 ± 0.1 cf. 35.2 ± 0.18 C; ES = 0.26–0.35). High-intensity running (ES = 0.27) and peak sprint speed were higher (ES = 0.46–0.56) during the PHM compared with the CON trial. Time spent above 20 W·kg-1 also increased in the first quartile of the PHM compared with the CON trial (ES = 0.18). All other between trial comparisons of performance were unclear. HRmean (ES = 0.38) was higher in PHM compared with CON, while differences in RPEmean (ES = 20.19) were unclear. There are small to large increases in high-intensity activity performed during a playing bout when rugby players wear a PHM garment after a warmup. Rugby players should consider PHM during extended periods between a warm-up and starting a match. [ABSTRACT FROM AUTHOR]

This study compared the movement demands of players competing in matches from the elite Australian and European rugby league competitions. Methods: Global positioning system devices were used to measure 192 performances of forwards, adjustables, and outside backs during National Rugby League (NRL; n = 88) and European Super League (SL; n = 104) matches. Total and relative distances covered overall and at low (0-3.5 m/s), moderate (3.6-5 m/s), and high (>5 m/s) speeds were measured alongside changes in movement variables across the early, middle, and late phases of the season. Results: The relative distance covered in SL matches (95.8 ± 18.6 m/min) was significantly greater (P < .05) than in NRL matches (90.2 ± 8.3 m/min). Relative low-speed activity (70.3 ± 4.9 m/min vs 75.5 ± 18.9 m/min) and moderate-speed running (12.5 ± 3.3 m m/min vs 14.2 ± 3.8 m/min) were highest (P < .05) in the SL matches, and relative high-speed distance was greater (P < .05) during NRL matches (7.8 ± 2.1 m/min vs 6.1 ± 1.7 m/min). Conclusions: NRL players have better maintenance of high-speed running between the first and second halves of matches and perform less low- and moderate-speed activity, indicating that the NRL provides a higher standard of rugby league competition than the SL. [ABSTRACT FROM AUTHOR]

This study investigated the concurrent validity of a rugby-specific high-intensity intermittent running test against the internal, external, and perceptual responses to simulated match play. Thirty-six rugby league players (age 18.5 ± 1.8 years; stature 181.4 ± 7.6 cm; body mass 83.5 ± 9.8 kg) completed the prone Yo-Yo Intermittent Recovery Test (Yo-Yo IR1), of which 16 also completed the Yo-Yo IR1, and 2 x ~20 minute bouts of a simulated match play (rugby league match simulation protocol for interchange players [RLMSP-i]). Most likely reductions in relative total, low-speed and high-speed distance, mean speed, and time above 20 W⋅kg-1 (high metabolic power [HMP]) were observed between bouts of the RLMSP-i. Likewise, rating of perceived exertion (RPE) and percentage of peak heart rate (%HRpeak) were very likely and likely higher during the second bout. Pearson's correlations revealed a large relationship for the change in relative distance (r = 0.57--0.61) between bouts with both Yo-Yo IR1 tests. The prone Yo-Yo IR1 was more strongly related to the RLMSP-i for change in repeated sprint speed (r = 0.78 cf. 0.56), mean speed (r = 0.64 cf. 0.36), HMP (r = 0.48 cf. 0.25), fatigue index (r = 0.71 cf. 0.63), %HRpeak (r = -0.56 cf. -0.35), RPEbout1 (r = -0.44 cf. -0.14), and RPEbout2 (r = -0.68 cf. -0.41) than the Yo-Yo IR1, but not for blood lactate concentration (r = -0.20 to -0.28 cf. -0.35 to -0.49). The relationships between prone Yo-Yo IR1 distance and measures of load during the RLMSP-i suggest that it possesses concurrent validity and is more strongly associated with measures of training or match load than the Yo-Yo IR1 using rugby league players. [ABSTRACT FROM AUTHOR]

Purpose: This study assessed the reliability of a rugby league movement-simulation protocol, relative to interchanged players (RLMSP-i). Methods: Fifteen male participants completed 2 trials of the RLMSP-i, separated by 1 wk. The RLMSP-i comprised low- to moderate-intensity running, interspersed by high-intensity sprinting and tackling activity, based on global positioning system (GPS) data recorded during Super League performances. Results: The lowest coefficient of variation (CV ± 95% CI) was observed for total m/min during both interchange bout 1 (1.1% ± 0.2%) and bout 2 (1.0% ± 0.2%). The percentage of heart rate peak and ratings of perceived exertion demonstrated CVs of 1.2-2.0% and 2.9-3.5%, respectively. The poorest agreement between trials was found for blood lactate concentration (16.2% ± 2.8%). In no case was the CV smaller than the smallest worthwhile change, yet in every case the moderate changes were larger than the CV. Conclusions: The RLMSP-i's reliability is sufficient to enable the detection of moderate changes in various performance and physiological measurements that accurately simulate some, but not all, aspects of rugby league matches. [ABSTRACT FROM AUTHOR]

Rugby league is a contact team sport performed at an average intensity similar to that of other team sports (~70-80% VO2max), made up of unsystematic movements of varying type, duration, and frequency. The high number of collisions, repeated eccentric muscle contractions associated with accelerating and decelerating, and prolonged aerobic nature of rugby league matches result in the development of fatigue in the days after exercise. Monitoring the presence and magnitude of this fatigue to maximize performance and training adaptation is an important consideration for applied sports scientists. Several methods have been proposed to measure the magnitude of fatigue in athletes. Perceptual measures (eg, questionnaires) are easy to employ and are sensitive to changes in performance. However, the subjective nature of such measures should be considered. Blood biochemical markers of fatigue may provide a more objective measure of homeostatic disturbances associated with fatigue; however, the cost, level of expertise required, and high degree of variability of many of these measures often preclude them from being used in the applied setting. Accordingly, simple measure of muscle function (eg, jump height) and simulated performance offer the most practical and appropriate method of determining the extent of fatigue experienced by rugby league players. A meaningful change in each measure of fatigue for the monitoring of players can be easily determined, provided that the reliability of the measure is known. Multiplying the coefficient of variation by 0.3, 0.9, and 1.6 can be used to determine a small, moderate, and large change, respectively. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to quantify changes in heart rate (HR) and movement speeds in interchanged and whole-match players during 35 elite rugby league performances. Methods: Performances were separated into whole match, interchange bout 1, and interchange bout 2 and further subdivided into match quartiles. Mean percentages of peak HR (%HRpeak) and total and high-intensity running (> 14 km/h) meters per minute (m/ min) were recorded. Results: For whole-match players, a decline in high-intensity m/min and %HRpeakwas observed between successive quartiles (P < .05). High-intensity m/min during interchange 1 also progressively declined, although initial m/min was higher than whole match (24.2 ± 7.9 m/min vs 18.3 ± 4.7 m/min, P = .018), and %HRpe3k did not change over match quartiles (P > .05). During interchange 2, there was a decline in high-intensity m/min from quartile 1 toquartile3 (18 ±4.1 vs 13.4 ±5 m/min, P= .048) before increasing in quartile 4. Quartiles 1 and 2 also showed an increase in %HRpeak (85.2 ± 6.5 vs 87.3 ± 4.2%, P = .022). Conclusions: Replacement players adopted a high initial intensity in their first match quartile before a severe decline thereafter. However, in a second bout, lower exercise intensity at the outset enabled a higher physiological exertion for later periods. These findings inform interchange strategy and conditioning for coaches while also providing preliminary evidence of pacing in team sport. [ABSTRACT FROM AUTHOR]

The study assesses the test–retest reliability of movement and physiological measures during a simulated rugby match that employed activities performed in a stochastic order. Twenty male rugby players (21.4 ± 2.1 y) completed two trials of a 2 × 23 min rugby movement simulation protocol during which the order of events was performed in a stochastic order, with 7–10 days between trials. Movement characteristics, heart rate (HR), RPE, maximum voluntary contraction (MVC), voluntary activation (VA%) of the quadriceps, Stroop test and subjective task load rating (NASA-TLX) were measured. The most reliable measures of external load was relative distance (typical error [TE] and CV% = 1.5–1.6 m min−1 and 1.4–1.5%, respectively), with all other movement characteristics possessing a CV% <5%. The most reliable measure of internal load, neuromuscular function and perceptual measures were for %HRmax (TE and CV% = 1.4–1.7% and 1.4–2.1%, respectively), MVC before (TE and CV% = 10.8–14.8 N·m and 3.8–4.6%, respectively), and average RPE (TE and CV% = 0.5–0.8 AU and 3.6–5.5%, respectively). The Stroop test, NASA-TLX and blood lactate produced the least reliable measures (CV% >5%). Future studies can confidently examine changes in several perceptual, neuromuscular, physiological and movement measures related to rugby activity using stochastic movements. [ABSTRACT FROM AUTHOR]

Carbohydrate and caffeine improves high-intensity running of elite rugby league interchange players during simulated match play. J Strength Cond Res 33(5): 1320-1327, 2019-The study examined the effects of carbohydrate and caffeine ingestion on simulated rugby league interchange performance. Eight male elite rugby league forwards completed 2 trials of a rugby league simulation protocol for interchange players 7 days apart in a randomized crossover design, ingesting either carbohydrate (CHO; 40 g -h -1 ) or carbohydrate and caffeine (CHO-C) (40 g -h -1 + 3 mg-kg-1 ) drink. Movement characteristics, heart rate, ratings of perceived exertion (RPE), and countermovement jump (CMJ) height were measured during the protocol. CHO-C resulted in likely to very likely higher mean running speeds (effect size [ES] 0.43-0.75), distance in highintensity running (ES 0.41-0.64), and mean sprint speeds (ES 0.39-1.04) compared with CHO. Heart rate was possibly to very likely higher (ES 0.32-0.74), and RPE was likely to very likely lower (ES -0 .5 3 to 0.86) with CHO-C. There was a likely trivial to possibly higher CMJ in CHO-C compared with CHO (ES 0.07-0.25). The coingestion of carbohydrate with caffeine has an ergogenic effect to reduce the sense of effort and increase high-intensity running capability that might be used to enhance interchange running performance in elite rugby league players. [ABSTRACT FROM AUTHOR]

The capacity to sustain high-speed running is important for rugby league players. Transient fatigue, described as a reduction in high-speed running in the 5 minutes after a peak 5-minute period, is a phenomenon observed during rugby league matches. This concept has recently been questioned based on the proposed confounding influence of ball-in-play time during these periods. Therefore, this study examined the changes in high-speed running (>14 km⋅h-1) of elite rugby league players, and ball-in-play time, during the peak, subsequent, and mean 5-minute periods of 5 competitive matches using 5-Hz Global Positioning System devices. The suitability of ball-in-play time as a covariate was also evaluated. The high-speed running and ball-in-play time was different between peak (26.7 ± 5.5 m⋅min-1 and 177 ± 37 seconds) and subsequent (12.1 ± 6.2 m⋅min-1 and 147 ± 37 seconds) 5-minute periods (p ≤ 0.05; most likely ↓). However, there was no relationship (r = 0.01 to -0.13; p > 0.05) between ball-in-play time and high-speed running, and ball-in-play time was not independent of the match period. This study has reaffirmed the presence of transient fatigue during elite rugby league matches but questioned the influence of ball-in-play time as a confounding factor. These observations have implications for the design of appropriate training practices and informing tactical strategies used by coaches. Most importantly, any practitioner wishing to measure transient fatigue could follow a similar statistical approach taken herein and based on the current findings would not need to account for ball-in-play time as a confounding variable. [ABSTRACT FROM AUTHOR]

This study investigated changes in body composition in relation to training load determined using RPE and duration (sRPE), and its relationship with physical qualities over a preseason period. Sixteen professional academy players (age = 17.2 ± 0.7 years; stature = 179.9 ± 4.9 cm; body mass = 88.5 ± 10.1 kg) participated in the study. Body composition was assessed before and after each training phase and physical qualities assessed at the start and end of preseason. Across the whole preseason period, skinfold thickness, body fat percentage and fat mass were most likely lower (ES = −0.73 to −1.00), and fat free mass and lean mass were likely to most likely higher (ES = 0.31 to 0.40). Results indicated that the magnitude of change appeared phase-dependent (ES = −0.05 to −0.85) and demonstrated large individual variability. Changes in physical qualities ranged from unclear to most likely (ES = −0.50 to 0.64). Small to moderate correlations were observed between changes in body composition, and TL with changes in physical qualities. This study suggests training phase and TL can influence a player’s body composition; that large inter-participant variability exists; and that body composition and TL are related to the change in physical qualities. [ABSTRACT FROM AUTHOR]

This study examined how starting each shuttle in the prone position altered the internal, external and perceptual responses to the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1). Using a randomized crossover design, 17 male rugby players completed the Yo-Yo IR1 and prone Yo-Yo IR1 on two separate occasions. External loads (via microtechnology), , heart rate (HR) and rating of perceived exertion (RPE) were measured at 160, 280 and 440 m (sub-maximal) and when the test was terminated (peak). The pre-to-post change in blood lactate concentration (Δ[La]b) was determined for both tests. All data were analysed using effect sizes (ES) and magnitude-based inferences. Between-trial differences (ES ± 90% CL) indicated that total distance was most likely lower (−1.87 ± 0.19), whereas other measures of peak external load were likely to very likely higher during the prone Yo-Yo IR1 (0.62-1.80). Sub-maximal RPE was likely to most likely higher (0.40-0.96) and peak RPE very likely higher (0.63 ± 0.41) in the prone Yo-Yo IR1. The change in [La]b was likely higher after the prone Yo-Yo IR1. Mean HR was possibly lower at 440 m (−0.25 ± 0.29) as was peak HR (−0.26 ± 0.25) in the prone Yo-Yo IR1. , and were likely to very likely higher at 280 and 440 m (ES = 0.36-1.22), while peak values were possibly to likely higher (ES = 0.23-0.37) in the prone Yo-Yo IR1. Adopting a prone position during the Yo-Yo IR1 increases the internal, external and perceptual responses, placing greater emphasis on metabolically demanding actions typical of rugby.  [ABSTRACT FROM AUTHOR]

This study sought to determine the effects of variable resistance using chain resistance on bench throw performance. Eight male rugby union players (19.4 ± 2.3 y, 88.8 ± 6.0 kg, 1RM 105.6 ± 17.0 kg) were recruited from a national league team. In a randomised cross-over design participant's performed three bench throws at 45% one repetition maximum (1RM) at a constant load (No Chains) or a variable load (30% 1RM constant load, 15% 1RM variable load; Chains) with seven days between conditions. For each repetition the peak and mean velocity, peak power, peak acceleration and time to peak velocity were recorded. Differences in peak and mean power were very likely trivial and unclear between the Chains and No Chains conditions, respectively. Possibly greater peak and likely greater mean bar velocity were accompanied by likely to most likely greater bar velocity between 50-400 ms from initiation of bench press in the Chains compared to the No Chains condition. Accordingly, bar acceleration was very likely greater in the Chains compared to the No Chains condition. In conclusion, these results show that the inclusion of chain resistance can acutely enhance several variables in the bench press throw and gives support to this type of training. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the validity of an isometric midthigh pull dynamometer against a criterion measure (i.e., 1,000-Hz force platform) for assessing muscle strength in male youth athletes. Twenty- two male adolescent (age 15.3 ± 0.5 years) rugby league players performed 4 isometric midthigh pull efforts (i.e., 2 on the dynamometer and 2 on the force platform) separated by 5-minute rest in a randomized and counterbalanced order. Mean bias, typical error of estimate (TEE), and Pearson correlation coefficient for peak force (PF) and peak force minus body weight (PFBW) from the force platform were validated against peak force from the dynamometer (DynoPF). When compared with PF and PFBW, mean bias (with 90% confidence limits) for DynoPF was very large (-32.4 [-34.2 to -30.6] %) and moderate (-10.0 [-12.8 to -7.2] %), respectively. The TEE was moderate for both PF (8.1 [6.3-11.2] %) and PFBW (8.9 [7.0-12.4]). Correlations between DynoPF and PF (r 0.90 [0.79-0.95]) and PFBW (r 0.90 [0.80-0.95]) were nearly perfect. The isometric midthigh pull assessed using a dynamometer underestimated PF and PFBW obtained using a criterion force platform. However, strong correlations between the dynamometer and force platform suggest that a dynamometer provides an appropriate alternative to assess isometric midthigh pull strength when a force platform is not available. Therefore, practitioners can use an isometric midthigh pull dynamometer to assess strength in the field with youth athletes but should be aware that it underestimates peak force. [ABSTRACT FROM AUTHOR]

This study determined the validity of the Just Jump System® (JJS) for measuring flight time, jump height and peak power output (PPO) in elite rugby league players. 37 elite rugby league players performed 6 countermovement jumps (CMJ; 3 with and 3 without arms) on a jump mat and force platform. A sub-sample (n = 28) was used to cross-validate the equations for flight time, jump height and PPO. The JJS systematically overestimated flight time and jump height compared to the force platform (P < 0.05), but demonstrated strong associations for flight time (with R² = 0.938; without R² = 0.972) and jump height (with R² = 0.945; without R² = 0.987). Our equations revealed no systematic difference between corrected and force platform scores and an improved the agreement for flight time (Ratio limits of agreement: with 1.00 vs. 1.36; without 1.00 vs. 1.16) and jump height (with 1.01 vs. 1.34; without 1.01 vs. 1.15), meaning that our equations can be used to correct JJS scores for elite rugby players. While our equation improved the estimation of PPO (with 1.02; without 1.01) compared to existing equations (Harman: 1.20; Sayers: 1.04), this only accounted for 64 and 69 % of PPO. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate how the type of contact influences physiological, perceptual and locomotive load during a simulated rugby league match. Eleven male university rugby league players performed two trials of the rugby league movement simulation protocol for interchange forwards with a traditional soft tackle bag and a weighted tackle sled to replicate contact demands. The interchange forward-specific simulation was chosen given the contact frequency is higher for this group of players compared to whole match players. Locomotive rate, sprint speed, tackle intensity, heart rate (HR) and rating of perceived exertion were analysed during the first and second bouts that replicated two ~23 min on-field passages. Countermovement jump (CMJ) was measured before and immediately after each trial. More time was spent in heart rate zone between 91 and 100% HRpeakduring the first (effect size ± 90% confidence interval: 0.44 ± 0.49) and second bouts (0.44 ± 0.43), and larger (0.6 ± 0.69) decrements in CMJ performance were observed during the sled trial (5.9,s = 4.9%) compared to the bag trial (2.6,s = 5.4%). Changing the type of contact during the match simulation subtly altered both the internal and external loads on participants. Using a standard tackle bag results in faster sprint speed to contact, but lower overall high-intensity running. Conversely, a heavier tackle object increases the internal load and results in greater lower limb neuromuscular fatigue as reflected by the decrease in CMJ performance. [ABSTRACT FROM PUBLISHER]

Rugby League (RL) is a high-impact collision sport characterised by repeated sprints and numerous high-speed impacts and consequently players often report immediate and prolonged muscle soreness in the days after a match. We examined muscle soreness after matches during a full season to understand the extent to which match characteristics influence soreness. Thirty-one elite Super League players provided daily measures of muscle soreness after each of the 26 competitive fixtures of the 2012 season. Playing position, phase of the season, playing surface and match characteristics were recorded from each match. Muscle soreness peaked at day 1 and was still apparent at day 4 post-game with no attenuation in the magnitude of muscle soreness over the course of the season. Neither playing position, phase of season or playing surface had any effects on the extent of muscle soreness. Playing time and total number of collisions were significantly correlated with higher ratings of muscle soreness, especially in the forwards. These data indicate the absence “contact adaptations” in elite rugby players with soreness present throughout the entire season. Strategies must now be implemented to deal with the physical and psychological consequences of prolonged feeling of pain. [ABSTRACT FROM AUTHOR]

Rugby union (RU) is a complex high-intensity intermittent collision sport with emphasis placed on players possessing high lean body mass and low body fat. After an 8 to 12-week pre-season focused on physiological adaptations, emphasis shifts towards competitive performance. However, there are no objective data on the physiological demands or energy intake (EI) and energy expenditure (EE) for elite players during this period. Accordingly, in-season training load using global positioning system and session rating of perceived exertion (sRPE), alongside six-day assessments of EE and EI were measured in 44 elite RU players. Mean weekly distance covered was 7827 ± 954 m and 9572 ± 1233 m with a total mean weekly sRPE of 1776 ± 355 and 1523 ± 434 AU for forwards and backs, respectively. Mean weekly EI was 16.6 ± 1.5 and 14.2 ± 1.2 megajoules (MJ) and EE was 15.9 ± 0.5 and 14 ± 0.5 MJ. Mean carbohydrate (CHO) intake was 3.5 ± 0.8 and 3.4 ± 0.7 g.kg−1 body mass, protein intake was 2.7 ± 0.3 and 2.7 ± 0.5 g.kg−1 body mass, and fat intake was 1.4 ± 0.2 and 1.4 ± 0.3 g.kg−1 body mass. All players who completed the food diary self-selected a 'low' CHO 'high' protein diet during the early part of the week, with CHO intake increasing in the days leading up to a match, resulting in the mean EI matching EE. Based on EE and training load data, the EI and composition seems appropriate, although further research is required to evaluate if this diet is optimal for match day performance [ABSTRACT FROM AUTHOR]

Rugby league is a collision sport which traditionally adopts a large emphasis on lean muscle mass. Currently there is limited research on the anthropometry of European Super League players. The aim of this study was to assess body composition using Dual Energy X-ray Absorptiometry (DXA) scans to identify the typical profile of elite rugby league players. One hundred and twelve players from five different clubs competing in the European Super League were recruited for the study. DXA scans were performed and the total mass, lean mass, fat mass and percentage body fat were reported for each positional group. For the Fullback and Wingers, Centres, Half Backs, Hookers, Props and Back Row Forwards the mean (SD) body fat percentage was 13 (2.1), 13 (2.4), 12 (3.4), 15 (3.9), 16 (4.3) and 15 (2.1)%, respectively, and total mass was 86 (8.2), 91 (6.6), 81 (8), 84 (9.5) 102 (8.5) and 93 (5.5) kg, respectively. Despite small to very large inter positional differences in all anthropometric variables (effect sizes = −0.08 to 2.56), particularly between the Prop and the other playing positions, there was large intra-position variation in body fat, lean mass and total mass making a standardised position specific profile difficult to establish. When used with other key performance indicators, these data provide the first multi-team anthropometric profile of elite Super League players that can be used to guide individualised training and nutrition practices for current and aspiring athletes. [ABSTRACT FROM PUBLISHER]

The article presents research on the impact of heavy eccentric loading on a conditioning activity as well as its effect on post-activation potentiation (PAP) of rugby football players in Australia. Results of the study indicate the capability of supra-maximal eccentric loading movement to induce PAP effect in the upper body, the inclusion of the training programme of an athlete, and the increase in muscular power output.

The article discusses research which was conducted to compare the internal and external match demands imposed on international and regional standard male touch rugby players. Researchers evaluated 12 international players and 9 regional players. They found that performance in men’s touch rugby is characterized by more relative high-speed running and better repeated sprint capacities in higher standard players.

The article reports on research which was conducted to evaluate changes in anthropometry and performance and their interrelationship during three seasons of play in elite youth rugby league players. Researchers evaluated 13 players. They found that over the course of three seasons there were increases in lean body mass in the players which helped them generate horizontal speed and vertical power.

This study compared technical actions, movements, heart rates and perceptual responses of selected and unselected youth rugby league players during matches (under-15 to under-17 age groups). The players’ movements and heart rates were assessed using 5 Hz Global Positioning Systems (GPSs), while their technical actions were analysed using video analysis. The maturity of each player was predicted before each season for statistical control. There were no differences (P > 0.05) between selected and unselected players in the under-15 or the under-17 age group for any variables. However, in the under-16 age group, the selected players (57.1 ± 11.9 min) played for longer than the unselected players (44.1 ± 12.3 min;P = 0.017; ES = 1.08 ± CI = 0.87), and covered more distance (5181.0 ± 1063.5 mcf. 3942.6 ± 1108.6 m, respectively;P = 0.012; ES = 1.14 ± CI = 0.88) and high-intensity distance (1808.8 ± 369.3 mcf.1380.5 ± 367.7 m, respectively;P = 0.011; ES = 1.16 ± CI = 0.88). Although successful carries per minute was higher in the selected under-15 age group, there were no other differences (P > 0.05) in match performance relative to playing minutes between groups. Controlling for maturity, the less mature, unselected players from the under-16 age group performed more high-intensity running (P < 0.05). Our findings question the use of match-related measurements in differentiating between selected and unselected players, showing that later maturing players were unselected, even when performing greater high-intensity running during matches. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between the physical abilities of adolescent rugby league players and tackling and ball-carrying skills performed during matches, across three seasons (under-15 to under-17). The players were measured each season for acceleration (10–30 m), peak and mean speed (10–30 m), sprinting force (10–30 m), aerobic power, counter-movement jump (CMJ) height and jumping power. The matches were filmed and analysed for ball-carrying and tackling frequency per minute (successful and unsuccessful outcomes). There were strong relationships between successful carries∙min–1and 10 m force in the under-15 (R= 0.61,P< 0.001), under-16 (R= 0.69,P< 0.001) and under-17 groups (R= 0.64,P< 0.001). There were also strong and moderate relationships between predicted vertical power and successful carries∙min–1in the under-15 (R= 0.63,P= 0.011) and under-17 group (R= 0.40,P= 0.030), respectively. There were no relationships between carries or tackles and any other performance indicators. These findings suggest that acceleration, in accordance with gains in body mass, support ball-carrying but not tackling performance. Performance measurements, such as CMJ or aerobic power, do not support ball-carrying ability among youth rugby league players. [ABSTRACT FROM PUBLISHER]

The article discusses a study of various physiological and performance indicators in rugby league players during an intense 5-day tournament competition with short recovery times between matches. The subjects were evaluated for peak power and force of plyometric press-up and countermovement jump, blood creatine kinase levels, and subjective well-being on each day of the tournament. The results confirm the development of fatigue and its effects on speed, acceleration, and tackling ability.

The aim of this study was to assess the external validity and reliability of a novel rugby league match simulation protocol. With ethical approval, 16 males (age 22.4 ± 7.1 years, estimated52.1 ± 4.5 ml · kg−1 · min−1) performed the rugby league match simulation protocol on two occasions 10 to 14 days apart. During the rugby league match simulation protocol participants covered a total distance of 8,444 ± 212 m, at an overall locomotive rate of 97.3 ± 2.5 m · min−1. In addition, changes in very high (−22.4%), high (−8.6%) and low intensity (1.6%) running locomotive rates from the first to the fourth quarter were observed. The magnitude of these movement characteristics did not differ significantly (P > 0.05) between repeated trials, with coefficients of variation of 1.1, 4.2 and 10.6%, and 95% limits of agreement of −0.4 ± 4.0, −0.3 ± 3.6, and −0.2 ± 4.4 m · min−1for overall, high and very high intensity running locomotive rates, respectively. On this evidence, the rugby league match simulation protocol replicates the movement demands observed during elite rugby league matches. Furthermore, the protocol can be performed reliably amongst non-elite sports players and thereby has the potential to be used as a tool for monitoring the effectiveness of various interventions on physical match performance. [ABSTRACT FROM PUBLISHER]

In this study, we investigated changes in creatine kinase, perceptual and neuromuscular fatigue of professional rugby league players after match-play. Twenty-three male rugby league players (10 backs, 13 forwards) had their creatine kinase, perceptual ratings of fatigue, attitude to training, muscle soreness, and flight time in a countermovement jump measured before and 1 and 2 days after (day 1 and day 2 respectively) league matches. Total playing time, offensive and defensive contacts were also recorded for each player. Creatine kinase was higher both 1 and 2 days after than before matches (P < 0.05) in forwards and backs. Similarly, perceived fatigue and muscle soreness were higher than pre-match on both days 1 and 2 (P < 0.05), but did not differ between groups (P > 0.05). Jump performance was lower on day 1 but not day 2 for both groups (P < 0.05). While total playing time was longer in backs (P < 0.05), relative frequencies for all contacts were greater in forwards (P < 0.05). Contacts for forwards were correlated with all markers of fatigue (P < 0.05), but only flight time was correlated with offensive contacts in backs (P < 0.05). Despite the mechanisms of fatigue being different between forwards and backs, our results highlight the multidimensional nature of fatigue after a rugby league match and that these markers do not differ between positions. [ABSTRACT FROM PUBLISHER]

There has been no previous investigation of the concurrent validity and reliability of the current 5 Hz global positioning system (GPS) to assess sprinting speed or the reliability of integrated GPS–accelerometer technology. In the present study, we wished to determine: (1) the concurrent validity and reliability of a GPS and timing gates to measure sprinting speed or distance, and (2) the reliability of proper accelerations recorded via GPS–accelerometer integration. Nineteen elite youth rugby league players performed two over-ground sprints and were simultaneously assessed using GPS and timing gates. The GPS measurements systematically underestimated both distance and timing gate speed. The GPS measurements were reliable for all variables of distance and speed (coefficient of variation [CV] = 1.62% to 2.3%), particularly peak speed (95% limits of agreement [LOA] = 0.00 ± 0.8 km · h−1; CV = 0.78%). Timing gates were more reliable (CV = 1% to 1.54%) than equivalent GPS measurements. Accelerometer measurements were least reliable (CV = 4.69% to 5.16%), particularly for the frequency of proper accelerations (95% LOA = 1.00 ± 5.43; CV = 14.12%). Timing gates and GPS were found to reliably assess speed and distance, although the validity of the GPS remains questionable. The error found in accelerometer measurements indicates the limits of this device for detecting changes in performance. [ABSTRACT FROM PUBLISHER]

This study investigated symptoms of exercise-induced muscle damage following a simulated rugby league game. Ten male participants were assessed before, immediately after (0 h), and 24 and 48 h after the simulated game. Perceived muscle soreness was higher at all time points (P=0.001) and creatine kinase values were increased at 24 h following the simulated game (P=0.001). Peak knee extensor torque at 60 deg · s−1 was reduced up to 48 h (P =0.04) but was unchanged at 240 deg · s−1. Similarly, peak knee flexor torque at 60 deg · s−1 was lower than baseline up to 24 h, while at 240 deg · s−1 it was reduced at 24 h only (P=0.045). Correlations between changes in strength loss of the knee extensors and fat mass to fat-free mass ratio reveleaved no significant relationship between variables (P >0.05). In addition, countermovement jump performance was reduced at 0 and 24 h following the simulated game (P=0.008). Our results suggest that symptoms of exercise-induced muscle damage occur up to 48 h following a simulated rugby league match. Coaches should be cognisant of the large increases in muscle soreness and reductions in slow velocity force generation, and should adapt training accordingly in the 48 h period following a game. [ABSTRACT FROM AUTHOR]

The aim of this study was to quantify the changes in locomotive rates across the duration of senior elite rugby league matches. A semi-automated image recognition system (ProZone 3, ProZone®, Leeds, England) was used to track the movements of 59 players from six teams during three competitive matches. The players were classified into one of four positional groups: props (n = 9), back row (n = 9), pivots (n = 14) or outside backs (n = 27). Players' movements were classified as low, high or very high intensity running and reported as locomotive rates (distance covered per minute played) for successive quarters of each match. Analysis of variance revealed that only the outside backs showed a significantly lower overall locomotive rate during the final quarter compared to the first (P < 0.05). However, locomotive rates for high and very high intensity running during the final quarter were significantly lower (P < 0.05) than the first quarter among outside backs, pivots and props despite no change in the rate of involvements in contact. On the basis of these findings, it is suggested that high and very high intensity running locomotive rates may be more affective methods of detecting fatigue during competitive matches than overall locomotive rate. [ABSTRACT FROM AUTHOR]

Twelve elite players from an English Super League club consented to participate in the present study using portable global positioning system (GPS) devices to assess position-specific demands. Distances covered at low-intensity running, moderate-intensity running, high-intensity running, very high-intensity running, and total distance were significantly (P < 0.05) lower in forwards compared with outside backs and adjustables. Metres per minute was higher in adjustables and forwards, owing to higher values for relative distance in medium-intensity running and a rise in high-intensity running from previous absolute values. Sprint distance, sprint frequency, and peak speed were higher in outside backs than both adjustables and forwards. A moderate, significant correlation (r = 0.62, P = 0.001) was apparent between session ratings of perceived exertion and summated heart rate. Results support the requirement for position-specific conditioning and provide preliminary evidence for the use of session ratings of perceived exertion as a measure of match load. [ABSTRACT FROM AUTHOR]

In rugby league, tests of sport-specific skill often involve subjective assessments of performance by observers of varying qualification. However, the reliability of such subjective assessments has yet to be investigated via appropriate statistical techniques. Therefore, the aims of the current study were to investigate: (1) the intra-observer reliability of a non-qualified observer (‘novice’) and (2) the inter-observer reliability of the three observers (two qualified ‘experts’ and one novice observer) in the assessment of catching, passing and tackling (stages 1 and 2) ability in elite adolescent rugby league players (age: 14.7±0.5 years). Players performed each skill element within a simulated practice drill and were assessed in ‘real time’ by the observers according to pre-defined criteria. An overall bias (P<0.05) was revealed between the observers in stage 1 of catching and stage 1 of passing, the differences being higher for the novice compared to both expert coaches for each stage of catching and the first stage of passing, and between expert 2 and the novice for stage 2 of tackling. No comparisons met the pre-determined analytical goal of ‘perfect agreement’, for any of the skill components. Comparisons between the expert observers did not reach perfect agreement, with the lowest values occurring for both tackling skill stages (60–65%). None of the tests employed were sufficiently reliable to potentially discern between players of differing ability, which may mean up to 56% of players' skill being misinterpreted. The credibility of such assessments should be questioned and alternative tests considered. [ABSTRACT FROM AUTHOR]