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Professional rugby league (RL) football is a contact sport involving repeated collisions and high-intensity efforts; both training and competition involve high energy expenditure. The present review summarizes and critiques the available literature relating the physiological demands of RL to nutritional requirements and considers potential ergogenic supplements that could improve players' physical capacity, health, and recovery during the preparatory and competition phases of a season. Although there may not be enough data to provide RL-specific recommendations, the available data suggest that players may require approximately 6-8 g·kg-1·day-1 carbohydrate, 1.6-2.6 g·kg-1·day-1 protein, and 0.7-2.2 g·kg-1·day-1 fat, provided that the latter also falls within 20-35% of total energy intake. Competition nutrition should maximize glycogen availability by consuming 1-4 g/kg carbohydrate (∼80-320 g) plus 0.25 g/kg (∼20-30 g) protein, 1-4 hr preexercise for 80-120 kg players. Carbohydrate intakes of approximately 80-180 g (1.0-1.5 g/kg) plus 20-67 g protein (0.25-0.55 g/kg) 0-2 hr postexercise will optimize glycogen resynthesis and muscle protein synthesis. Supplements that potentially improve performance, recovery, and adaptation include low to moderate dosages of caffeine (3-6 mg/kg) and ∼300 mg polyphenols consumed ∼1 hr preexercise, creatine monohydrate "loading" (0.3 g·kg-1·day-1) and/or maintenance (3-5 g/day), and beta-alanine (65-80 mg·kg-1·day-1). Future research should quantify energy expenditures in young, professional male RL players before constructing recommendations.

Purpose: To determine (1) how change-of-direction (COD) workloads influence PlayerLoad (PL) variables when controlling total distance covered and (2) relationships among collision workloads and PL variables during rugby league match play., Methods: Participants completed 3 protocols (crossover design) consisting of 10 repetitions of a 60-m effort in 15 s. The difference between protocols was the COD demands required to complete 1 repetition: no COD (straight line), 1° × 180° COD, or 3° × 180° COD. During rugby league matches, relationships among collision workloads, triaxial vector-magnitude PlayerLoad (PL VM ), anteroposterior + mediolateral PL (PL 2D ), and PL VM accumulated at locomotor velocities below 2 m·s -1 (ie, PL SLOW ) were examined using Pearson correlations (r) with coefficients of determination (R 2 )., Results: Comparing 3° × 180° COD to straight-line drills, PL VM ·min -1 (d = 1.50 ± 0.49, large, likelihood = 100%, almost certainly), PL 2D ·min -1 (d = 1.38 ± 0.53, large, likelihood = 100%, almost certainly), and PL SLOW ·min -1 (d = 1.69 ± 0.40, large, likelihood = 100%, almost certainly) were greater. Collisions per minute demonstrated a distinct (ie, R 2 < .50) relationship from PL VM ·min -1 (R 2 = .30, r = .55) and PL 2D ·min -1 (R 2 = .37, r = .61). Total distance per minute demonstrated a very large relationship with PL VM ·min -1 (R 2 = .62, r = .79) and PL 2D ·min -1 (R 2 = .57, r = .76)., Conclusions: PL variables demonstrate (1) large increases as COD demands intensify, (2) separate relationships from collision workloads, and (3) moderate to very large relationships with total distance during match play. PL variables should be used with caution to measure collision workloads in team sport.

Objectives: Collision frequency during rugby league matches is associated with team success, greater and longer lasting fatigue and increased injury risk. This study researched the sensitivity and specificity of microtechnology to count collision events during rugby league matches., Design: Diagnostic accuracy study., Methods: While wearing a microtechnology device (Catapult, S5), eight professional rugby league players were subjected to a total of 380 collision events during matches. Video footage of each match was synchronised with microtechnology data. The occurrence of each collision event was coded in comparison with whether that event was or was not detected by microtechnology., Results: Microtechnology detected 371 true-positive collision events (sensitivity=97.6±1.5%). When low-intensity (<1 PlayerLoad AU), short duration (<1s) events were excluded from the analysis, specificity was 91.7±2.5%, accuracy was 92.7±1.3%, positive likelihood ratio was 11.4×/÷1.4 and the typical error of estimate was 7.8%×/÷1.9 (d=0.29×/÷1.9, small). Microtechnology collisions were strongly and positively correlated with video coded collision events (r=0.96). The ability of microtechnology to detect collision events improved as the intensity and duration of the collision increased., Conclusions: Microtechnology can identify 97.6% of collision events during rugby league match-play. The typical error associated with measuring contact events can be reduced to 7.8%, with accuracy (92.7%) and specificity (91.7%) improving, when low-intensity (<1 PlayerLoad AU) and short duration (<1s) collision reports are excluded. This provides practitioners with a measurement of contact workload during professional rugby league matches., (Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Objectives: To investigate β-alanine supplementation use and level of knowledge amongst professional footballers., Design: Cross-sectional survey of Australian professional football players., Methods: Questionnaires assessing β-alanine supplementation behaviours, level of knowledge and sources of information were completed by professional rugby union (RU) (n=87), rugby league (RL) (n=180) and Australian Rules Football (ARF) (n=303) players., Results: Approximately 61% of athletes reported β-alanine use, however use by ARF football players (44%) was lower than that of RU (80%) and RL players (80%). The majority of respondents were not using β-alanine in accordance with recommendations. Only 35% of the participants were able to correctly identify the potential benefits of β-alanine supplementation. The main information sources that influenced players' decision to use β-alanine were strength and conditioning coach (71%) and dietitian (52%). Forty-eight per cent of athletes never read labels prior to supplementing and only 11% completed their own research on β-alanine. Compared to RL and ARF players, RU players had both a greater knowledge of β-alanine supplementation and better supplementation practices., Conclusions: Despite over half the surveyed professional footballers using β-alanine, the majority of athletes used β-alanine in a manner inconsistent with recommendations. A better understanding of the environment and culture within professional football codes is required before supplement use becomes consistent with evidence based supplement recommendations., (Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Purpose: To assess the impact of different repeated-high-intensity-effort (RHIE) bouts on player activity profiles, skill involvements, and neuromuscular fatigue during small-sided games., Participants: 22 semiprofessional rugby league players (age 24.0 ± 1.8 y, body mass 95.6 ± 7.4 kg)., Methods: During 4 testing sessions, they performed RHIE bouts that each differed in the combination of contact and running efforts, followed by a 5-min off-side small-sided game before performing a second bout of RHIE activity and another 5-min small-sided game. Global positioning system microtechnology and video recordings provided information on activity profiles and skill involvements. A countermovement jump and a plyometric push-up assessed changes in lower- and upper-body neuromuscular function after each session., Results: After running-dominant RHIE bouts, players maintained running intensities during both games. In the contact-dominant RHIE bouts, reductions in moderate-speed activity were observed from game 1 to game 2 (ES = -0.71 to -1.06). There was also moderately lower disposal efficiency across both games after contact-dominant RHIE activity compared with running-dominant activity (ES = 0.62-1.02). Greater reductions in lower-body fatigue occurred as RHIE bouts became more running dominant (ES = -0.01 to -1.36), whereas upper-body fatigue increased as RHIE bouts became more contact dominant (ES = -0.07 to -1.55)., Conclusions: Physical contact causes reductions in running intensity and the quality of skill involvements during game-based activities. In addition, the neuromuscular fatigue experienced by players is specific to the activities performed.

Purpose: To assess the influence of playing standard and physical fitness on pacing strategies during a junior team-sport tournament., Methods: A between-groups, repeated-measures design was used. Twenty-eight junior team-sport players (age 16.6 ± 0.5 y, body mass 79.9 ± 12.0 kg) from a high-standard and low-standard team participated in a junior rugby league tournament, competing in 5 games over 4 d (4 × 40-min and 1 × 50-min game). Players wore global positioning system (GPS) microtechnology during each game to provide information on match activity profiles. The Yo-Yo Intermittent Recovery Test (level 1) was used to assess physical fitness before the competition., Results: High-standard players had an initially higher pacing strategy than the low-standard players, covering greater distances at high (ES = 1.32) and moderate speed (ES = 1.41) in game 1 and moderate speed (ES = 1.55) in game 2. However, low-standard players increased their playing intensity across the competition (ES = 0.57-2.04). High-standard/high-fitness players maintained a similar playing intensity, whereas high-standard/low-fitness players reduced their playing intensities across the competition., Conclusions: Well-developed physical fitness allows for a higher-intensity pacing strategy that can be maintained throughout a tournament. High-standard/low-fitness players reduce playing intensity, most likely due to increased levels of fatigue as the competition progresses. Low-standard players adopt a pacing strategy that allows them to conserve energy to produce an "end spurt" in the latter games. Maximizing endurance fitness across an entire playing group will maximize playing intensity and minimize performance reductions during the latter stages of a tournament.

Purpose: To determine the influence the number of contact efforts during a single bout has on running intensity during game-based activities and assess relationships between physical qualities and distances covered in each game., Methods: Eighteen semiprofessional rugby league players (age 23.6 ± 2.8 y) competed in 3 off-side small-sided games (2 × 10-min halves) with a contact bout performed every 2 min. The rules of each game were identical except for the number of contact efforts performed in each bout. Players performed 1, 2, or 3 × 5-s wrestles in the single-, double-, and triple-contact game, respectively. The movement demands (including distance covered and intensity of exercise) in each game were monitored using global positioning system units. Bench-press and back-squat 1-repetition maximum and the 30-15 Intermittent Fitness Test (30-15IFT) assessed muscle strength and high-intensity-running ability, respectively., Results: There was little change in distance covered during the single-contact game (ES = -0.16 to -0.61), whereas there were larger reductions in the double- (ES = -0.52 to -0.81) and triple-contact (ES = -0.50 to -1.15) games. Significant relationships (P < .05) were observed between 30-15IFT and high-speed running during the single- (r = .72) and double- (r = .75), but not triple-contact (r = .20) game., Conclusions: There is little change in running intensity when only single contacts are performed each bout; however, when multiple contacts are performed, greater reductions in running intensity result. In addition, high-intensity-running ability is only associated with running performance when contact demands are low.

Objectives: This study examined the influence of physical qualities on markers of fatigue and muscle damage following rugby league match-play., Design: Between subjects design., Methods: Twenty-one male youth rugby league players (age 19.2 ± 0.7 years; height 180.7 ± 5.6 cm; body mass 89.9 ± 10.0 kg) participated in the study. Yo-Yo intermittent recovery test (level 1), 3 repetition maximum back squat and bench press were assessed prior to 2 competitive fixtures. Neuromuscular fatigue (countermovement jump [CMJ] and plyometric push-up [PP]), and blood creatine kinase (CK) were assessed before and after match-play. During match-play, movements were recorded using microtechnology. Players were divided into high- and low-groups based on physical qualities., Results: High Yo-Yo and squat performance resulted in greater loads during match-play (p<0.05). There were larger reductions in CMJ power in the low Yo-Yo group at both 24 (ES=-1.83), and 48 h post-match (ES=-1.33). Despite greater internal and external match loads, changes in CMJ power were similar between squat groups. There were larger increases in blood CK in the low Yo-Yo group at 24 (73% vs. 176%; ES=1.50) and 48 h post-match (28% vs. 80%; ES=1.22). Despite greater contact loads, the high squat group exhibited smaller changes in blood CK post-match (ES=0.25-0.39)., Conclusions: Post-match fatigue is lower in players with well-developed high-intensity running ability, and lower body strength, despite these players having greater internal and external match loads., (Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

The use of 3 or more efforts (running and contact), separated by short recovery periods, is widely used to define a "repeated high-intensity effort" (RHIE) bout in rugby league. It has been suggested that due to fatigue, players become less effective after RHIE bouts; however, there is little evidence to support this. This study determined whether physical performance is reduced after performing 1, 2, or 3 efforts with minimal recovery. Twelve semiprofessional rugby league players (age: 24.5 ± 2.9 years) competed in 3 "off-side" small-sided games (2 × 10-minute halves) with a contact bout performed every 2 minutes. The rules of each game were identical except for the number of contact efforts performed in each bout. Players performed 1, 2, or 3 × 5-second wrestling bouts in the single-, double- and triple-contact game, respectively. Movement demands of each game were monitored using global positioning system units. From the first to the second half, there were trivial reductions in relative distance during the single-contact game (ES = -0.13 ± 0.12), small reductions during the double-contact game (ES = -0.47 ± 0.24), and moderate reductions during the triple-contact game (ES = -0.74 ± 0.27). These data show that running intensity is progressively reduced as the number of contact efforts per bout is increased. Targeting defensive players and forcing them to perform 2 or more consecutive contact efforts is likely to lead to greater reductions in running intensity. Conditioning performing multiple contact efforts while maintaining running intensity should therefore be incorporated into training for contact team sports.

Purpose: Repeated sprinting incorporating tackles leads to greater reductions in sprint performance than repeated sprinting alone. However, the influence of physical contact on the running demands of game-based activities is unknown. The aim of this study was to determine whether the addition of physical contact altered pacing strategies during game-based activities., Methods: Twenty-three elite youth rugby league players were divided into 2 groups. Group 1 played the contact game on day 1 while group 2 played the noncontact game; 72 h later they played the alternate game. Each game consisted of offside touch on a 30 × 70-m field, played over two 8-min halves. Rules were identical between games except the contact game included a 10-s wrestle bout every 50 s. Microtechnology devices were used to analyze player movements., Results: There were greater average reductions during the contact game for distance (25%, 38 m/min, vs 10%, 20 m/min; effect size [ES] = 1.78 ± 1.02) and low-speed distance (21%, 24 m/min, vs 0%, 2 m/s; ES = 1.38 ± 1.02) compared with the noncontact game. There were similar reductions in high-speed running (41%, 18 m/min, vs 45%, 15 m/min; ES = 0.15 ± 0.95)., Conclusions: The addition of contact to game-based activities causes players to reduce low-speed activity in an attempt to maintain high-intensity activities. Despite this, players were unable to maintain high-speed running while performing contact efforts. Improving a player's ability to perform contact efforts while maintaining running performance should be a focus in rugby league training.

Objectives: Physical contact is frequent in rugby league competition and is thought to be a major contributor to the fatigue and creatine kinase (CK) response, although direct evidence is lacking. The aim of this study was to investigate the influence that physical contact had on the fatigue and CK response to small-sided games., Design: Cross-over, counter-balanced study., Methods: Twenty-three junior elite rugby league players were divided into two groups. Group one played a contact game on day 1 before playing a non-contact game 72 h later; group two played the games in reverse order. The rules were identical for each game, with the only difference being a 10s contact bout every 50s during the contact game. Upper and lower body neuromuscular fatigue and blood concentrations of CK were assessed immediately before, immediately after, and 12 and 24h after the games. During each game, players wore global positioning system units to provide information on movements., Results: CK increased after both games, peaking immediately following the non-contact game; CK was still rising 24h following the contact game. The difference between the two conditions was practically meaningful at this point (likelihood=likely, 82%; ES=0.86). There were moderate to large reductions in upper body power following the contact game (ES=-0.74 to -1.86), and no reductions following the non-contact game., Conclusions: This study indicates that large increases in blood CK and upper body fatigue result from physical contact. Training sessions involving physical contact should be performed well in advance of scheduled games., (Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Objectives: The aim of this study was to assess the physiological responses to an intensified rugby league competition and explore the relationships between fatigue and match performance., Design: Prospective cohort study., Methods: Fifteen junior rugby league players (n=8 forwards, 7 backs; mean±SE, age 16.6±0.2 years; body mass 81.6±3.0kg; and height 178.9±1.8cm) competed in five 40min games over 5 days (two games each on days 1 and 2, one game on day 4, and no games on days 3 and 5). Over the competition, players performed a countermovement jump to assess neuromuscular fatigue, provided a fingertip blood sample to measure blood creatine kinase, and completed a questionnaire to monitor perceived wellbeing; ratings of perceived effort were recorded following each game. Global positioning system and video analysis of each game were used to assess match performance., Results: Over the first 3 days, there were progressive and large increases in neuromuscular fatigue which peaked 12h after game 4 (forwards ES=4.45, p=0.014; backs ES=3.62, p=0.029), and muscle damage which peaked 1h post game 4 (forwards ES=4.45, p=0.004; backs ES=3.94 p=0.012), as well as reductions in perceived wellbeing. These measures gradually recovered over the final 2 days of the competition. Compared to the backs, the forwards experienced greater increases in creatine kinase following game 2 (ES=1.30) and game 4 (ES=1.24) and reductions in perceived wellbeing (ES=0.25-0.46). Match intensity, high-speed running, and repeated-high intensity effort bouts decreased in games 4 and 5 of the competition. Small to large associations were observed between the changes in fatigue, muscle damage and match performance, with significant correlations between creatine kinase and repeated high-intensity effort bout number (r=-0.70, p=0.031) and frequency (r=0.74, p=0.002) and low-speed activity (r=-0.56, p=0.029)., Conclusions: Fatigue and muscle damage accumulate over an intensified competition, which is likely to contribute to reductions in high-intensity activities and work rates during competition., (Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

The purpose of this study was to examine the reliability and sensitivity of 3 ecologically valid repeated high-intensity exercise (RHIE) tests for professional rugby league (RL) and rugby union (RU) players. A further purpose was to investigate the relationship between RHIE performance and measures of speed (20-m sprint) and high-intensity intermittent running ability (yo-yo intermittent recovery test). Thirty-six RU and RL players were separated into 3 equal groups based on playing position: backs, RL forwards and RU forwards. Test-retest reliability was assessed by comparing total sprint time over 9 sprints during 2 identical testing sessions. The intraclass correlation coefficients (ICCs) for total sprint time were moderate to high (0.82, 0.97, and 0.94) and coefficient of variation (CV) low (4.2, 1.4, and 0.6%) for the backs, RL forwards, and RU forwards tests, respectively. However, sprint performance decrement scores were poorer, with ICC and CV of 0.78, 0.86, and 0.88 and 49.5, 48.2, and 35.8% for the backs, RL forwards, and RU forwards, respectively. Total sprint times for the backs, RL forwards, and RU forwards decreased over the 3 tests by 0.54, 0.53, and 2.09 seconds, respectively. Changes in RHIE total sprint time were moderately related to changes in 20-m sprint times (T1 to T2, r = 0.63; T2 to T3, r = 0.69; and T1 to T3, r = 0.63; all p < 0.05) but not yo-yo intermittent recovery test performances. This study has shown that the designed RL and RU RHIE tests have moderate to high reliability and produce significant improvements over a training period when total sprint times are compared.

The purpose of this study was to investigate the effect of changes in field size on the physiological and skill demands of small-sided games in elite junior and senior rugby league players. Sixteen elite senior rugby league players ([mean ± SE] age, 23.6 ± 0.5 years) and 16 elite junior rugby league players ([mean ± SE] age, 17.3 ± 0.3 years) participated in this study. On day 1, 2 teams played an 8-minute small-sided game on a small field (10-m width × 40-m length), whereas the remaining 2 teams played the small-sided game on a larger sized field (40-m width × 70-m length). On day 2, the groups were crossed over. Movement was recorded by a global positioning system unit sampling at 5 Hz. Games were filmed to count the number of possessions and the number and quality of disposals. The games played on a larger field resulted in a greater (p < 0.05) total distance covered, and distances covered in moderate, high, and very-high velocity movement intensities. Senior players covered more distance at moderate, high, and very-high intensities, and less distance at low and very-low intensities during small-sided games than junior players. Although increasing field size had no significant influence (p > 0.05) over the duration of recovery periods for junior players, larger field size significantly reduced (p < 0.05) the amount of short-, moderate-, and long-duration recovery periods in senior players. No significant between-group differences (p > 0.05) were detected for games played on a small or large field for the number or quality of skill involvements. These results suggest that increases in field size serve to increase the physiological demands of small-sided games but have minimal influence over the volume or quality of skill executions in elite rugby league players.

Objectives: To investigate the physical demands of professional rugby league match-play using microtechnology, and to compare these demands with typical training activities used to prepare players for competition., Design: Prospective cohort study., Methods: Thirty elite rugby league players participated in this study. Seven hundred and eighty-six. training data sets and 104 data sets from National Rugby League matches were collected over one playing season. Movement was recorded using a commercially available microtechnology unit (minimaxX, Catapult Innovations), which provided information on speeds, distances, accelerations, physical collisions and repeated high-intensity efforts., Results: Mean distances covered during match-play by the hit-up forwards, wide-running forwards, adjustables, and outside backs were 3,569 m, 5,561 m, 6,411 m, and 6,819 m, respectively. Hit-up forwards and wide-running forwards were engaged in a greater number of moderate and heavy collisions than the adjustables and outside backs, and more repeated high-intensity effort bouts per minute of play (1 bout every 4.8-6.3 min). The physical demands of traditional conditioning, repeated high-intensity effort exercise, and skill training activities were all lower than the physical demands of competition., Conclusions: These results demonstrate that absolute distances covered during professional rugby league matches are greater for outside backs, while the collision and repeated high-intensity effort demands are higher for hit-up forwards and wide-running forwards. The specific physical demands of competitive play, especially those demands associated with collisions and repeated high-intensity efforts, were not well matched by those observed in traditional conditioning, repeated high-intensity effort exercise, and skills training activities. Further research is required to investigate whether modifications need to be made to these training activities to better prepare players for the demands of National Rugby League competition., (Copyright © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

In this study, we investigated the relationship between physiological, anthropometric, and skill qualities and playing performance in professional rugby league players. Fifty-eight high-performance rugby league players underwent measurements for anthropometry (height, body mass, sum of seven skinfolds), physiological (speed, change of direction speed, lower body muscular power, repeated-sprint ability, prolonged high-intensity intermittent running ability, and estimated maximal aerobic power), technical skill (tackling proficiency, draw and pass proficiency), and perceptual skill (reactive agility, pattern recall, pattern prediction) qualities. National Rugby League matches were coded for attacking (e.g. line breaks, try assists, etc.) and defensive (e.g. missed tackles, tackling efficiency, etc.) statistics commonly used to assess rugby league playing performance. The number of line break assists was significantly associated (P < 0.05) with greater playing experience (r = 0.36), dual-task draw and pass proficiency (r = 0.54), reactive agility (r = 0.29), and pattern recall (r = 0.32) and prediction (r = 0.28) ability, while faster speed over 40 m (r = -0.42) was associated (P < 0.05) with a higher number of tries scored. Greater age and playing experience, better lower body muscular power, and faster 10 m and 40 m speed were significantly associated (P < 0.05) with the number of tackle attempts (positive), tackles completed (positive), and proportion of missed tackles (negative). These findings demonstrate that well-developed physical and skill qualities are associated with effective playing performance in National Rugby League players.

This study investigated the relative importance of physiological, anthropometric, and skill qualities to team selection in professional rugby league. Eighty-six high performance rugby league players underwent measurements of anthropometric (height, body mass, sum of seven skinfolds), physiological (speed, change of direction speed, lower body muscular power, repeated-sprint ability, prolonged high-intensity intermittent running ability, and maximal aerobic power), technical skill (tackling proficiency, draw and pass proficiency), and perceptual skill (reactive agility, pattern recall, pattern prediction) qualities. A linear discriminant analysis was also conducted comparing those players successful in gaining selection into the professional National Rugby League team with those not selected to determine which, if any, of these qualities could predict selection. Players selected to play in the first National Rugby League game of the season were older, more experienced, leaner, had faster 10 m and 40 m sprint times, and superior vertical jump performances, maximal aerobic power, tackling proficiency and dual-task draw and pass ability than non-selected players. Skinfold thickness and dual-task draw and pass proficiency were the only variables that contributed significantly (P < 0.05) to the discriminant analysis of selected and non-selected players. These findings suggest that selected physiological, anthropometric, and skill qualities may influence team selection in professional rugby league.

Objective: To document the frequency of physical collisions and incidence of contact injury in professional rugby league match-play., Design: Prospective cohort study., Methods: Video recordings of 77 National Rugby League (NRL) matches were coded for the number and type of physical collisions in which players were involved. Each match was analysed and coded for defensive (i.e. tackles, missed tackles, and ineffective tackles) and attacking collisions (i.e. tackled in possession, broken tackles, offloads, support runs, and decoy runs). Injuries that occurred as a result of a physical collision were also recorded., Results: The total number of physical collisions performed per game was greatest in the wide running forwards (47 [95% CI, 42-52]), and was significantly greater (P<0.05) than the hit-up forwards (36 [95% CI, 32-40]), adjustables (29 [95% CI, 26-32]), and outside backs (24 [95% CI, 22-27]) positional groups. A total of 48 collision injuries were sustained, resulting in an overall injury incidence of 10.6 (95% CI, 7.6-13.6) per 10,000 collisions. Injuries resulting from attacking collisions were consistently higher than injuries sustained in defensive collisions. Wide running forwards had the lowest incidence of injury, and the adjustables and outside backs had the highest incidence of injury., Conclusions: These results highlight the physical demands associated with collisions and tackles in professional rugby league. Furthermore, the results of this study suggest that playing position and the type of collision sustained have a greater influence over contact injury risk in rugby league than the number of physical collisions performed., (Copyright © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Objectives: To investigate the relationship between training load and injury in professional rugby league players;, Design: Prospective cohort study;, Methods: Seventy-nine professional rugby league players (mean±SD age, 23.3±3.8 years) participated in this four-year study. A periodized field, strength, and power training program was implemented, with training loads progressively increased in the general preparatory phase of the season and reduced during the competitive phase of the season. Training loads and injuries were recorded for each training session., Results: Training load was significantly related (P<0.05) to overall injury (r=0.82), non-contact field injury (r=0.82), and contact field injury (r=0.80) rates. Significant relationships were also observed between the field training load and overall field injury (r=0.68), non-contact field injury (r=0.65), and contact field injury (r=0.63) rates. Strength and power training loads were significantly related to the incidence of strength and power injuries (r=0.63). There was no significant relationship between field training loads and the incidence of strength and power injuries. However, strength and power training loads were significantly (P<0.01) associated with the incidence of contact (r=0.75) and non-contact (r=0.82) field training injuries., Conclusions: These findings suggest that the harder rugby league players train, the more injuries they will sustain, and that high strength and power training loads may contribute indirectly to field injuries. Monitoring of training loads and careful scheduling of field and gymnasium sessions to avoid residual fatigue is warranted to minimize the effect of training-related injuries on professional rugby league players., (Copyright © 2010 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

This study investigated the tackling ability of high-performance rugby league players and determined the relationship between physiological and anthropometric qualities and tackling ability in these athletes. Twenty professional (National Rugby League) and 17 semiprofessional (Queensland Cup) rugby league players underwent a standardized 1-on-1 tackling drill in a 10-m grid. Video footage was taken from the rear, side, and front of the defending player. Tackling proficiency was assessed using standardized technical criteria. In addition, all players underwent measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), acceleration (10-m sprint), change of direction speed (505 test), and lower body muscular power (vertical jump). Professional players had significantly greater (p ≤ 0.05) tackling proficiency than semiprofessional players (87.5 ± 2.0 vs. 75.0 ± 2.3%). Professional players were significantly (p ≤ 0.05) older, more experienced, leaner, and had greater acceleration than semiprofessional players. The strongest individual correlates of tackling ability were age (r = 0.41, p ≤ 0.05), playing experience (r = 0.70, p ≤ 0.01), skinfold thickness (r = -0.59, p ≤ 0.01), acceleration (r = 0.41, p ≤ 0.05), and lower body muscular power (r = 0.38, p ≤ 0.05). When hierarchical multiple regression analysis was performed to determine which of the variables predicted tackling ability, playing experience and lower body muscular power were the only variables that contributed significantly (r2 = 0.60, p ≤ 0.01) to the predictive model. From a practical perspective, strength and conditioning coaches should emphasize the development of acceleration, lower body muscular power, and lean muscle mass to improve tackling ability in high-performance rugby league players.

This study investigated the tackling ability of junior elite and subelite rugby league players, and determined the relationship between selected physiological and anthropometric characteristics and tackling ability in these athletes. Twenty-eight junior elite (mean ± SD age, 16.0 ± 0.2 years) and 13 junior subelite (mean ± SD age, 15.9 ± 0.6 years) rugby league players underwent a standardized 1-on-1 tackling drill in a 10-m grid. Video footage was taken from the rear, side, and front of the defending player. Tackling proficiency was assessed using standardized technical criteria. In addition, all players underwent measurements of standard anthropometry (stature, body mass, and sum of 7 skinfolds), acceleration (10-m sprint), change of direction speed (505 test), and lower body muscular power (vertical jump). Junior elite players had significantly greater (p < 0.05) tackling proficiency than junior subelite players (65.7 ± 12.5 vs. 54.3 ± 16.8%). Junior elite players tended to be taller, heavier, leaner, and have greater acceleration, change of direction speed, and muscular power, than the junior subelite players. The strongest individual correlates of tackling ability were acceleration (r = 0.60, p < 0.001) and lower body muscular power (r = 0.38, p < 0.05). When multiple linear regression analysis was performed to determine which of the physiological and anthropometric characteristics predicted tackling ability, fast acceleration was the only variable that contributed significantly (r2 = 0.24, p < 0.01) to the predictive model. These findings demonstrate that fast acceleration, and to a lesser extent, lower body muscular power contribute to effective tackling ability in junior rugby league players. From a practical perspective, strength and conditioning coaches should emphasize the development of acceleration and lower body muscular power qualities to improve tackling ability in junior rugby league players.

This study investigated the physiological and skill demands of 'on-side' and 'off-side' games in elite rugby league players. Sixteen male rugby league players participated in 'on-side' and 'off-side' games. Both small-sided games were played in a 40- × 40-m playing area. The 'off-side' game permitted players to have 3 'plays' while in possession of the ball. Players were permitted to pass backward or forward (to an 'off-side' player). The 'on-side' game also permitted players to have 3 'plays' while in possession of the ball. However, players were only permitted to pass backward to players in an 'on-side' position. Heart rate and movement patterns (via global positioning system) were recorded continuously throughout both games. Data were collected on the distance covered, number of high-acceleration and velocity efforts, and recovery between efforts. Video footage was also taken to track the performance of the players. Post hoc inspection of the footage was undertaken to count the number of possessions and the number and quality of disposals. In comparison to 'on-side' games, 'off-side' games had a greater number of involvements ("touches"), passes, and effective passes. However, the cognitive demands of 'on-side' games were greater than 'off-side' games. 'Off-side' games resulted in a greater total distance covered, greater distance covered in mild and moderate accelerations, and greater distance covered in low, moderate, and high-velocity efforts. There were also a greater number of short duration recovery periods between efforts in 'off-side' games. The results of this study demonstrate that 'off-side' games provide greater physiological and skill demands than 'on-side' games. 'Off-side' games may provide a practical alternative to 'on-side' games for the development of skill and fitness in elite rugby league players.

Research into rugby league has found a significant, positive relationship between training load and injury rates. However, there has been limited research investigating this relationship in the preseason period, and the relationship between training load, and injury among professional rugby league players is yet to be examined. The primary aim of this study was to examine the relationships between training load, various psychological data, and the incidence of injury during preseason training at a professional rugby league club. Thirty-six male professional rugby league players undertook a 14-week training program. Each player's training time, intensity rating, and injury status were recorded after each training session. In addition, players rated their sleep, food, energy, mood, and stress on a scale of 1-10 (with 1 being extremely poor and 10 being excellent) biweekly. Over the entire preseason period, a total of 2,877.9 training hours were recorded for the players, with an overall incidence of injury of 6.9 per 1,000 training hours. Higher training loads during the first half of the preseason corresponded to a higher injury rate in comparison to the second half of the preseason. No significant relationship was found between the preseason weekly injury rate and the weekly load, nor was there a relationship between injury and psychological data. These findings suggest no relationship between training load, psychological data, and injury incidence during the preseason training period in professional rugby league players. However, results suggest that players may have an increased risk of injury during the early preseason period. The findings of this study may be particularly useful in professional rugby league teams to determine when a player is at increased risk of injury, using their training loads and psychological data.