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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.

Purpose: To determine the utility of a running 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 (SITr, n = 15) sprint interval training group. Measures of speed, power, change of direction (CoD) ability, prone Yo-Yo IR1 performance and heart rate recovery (HRR) were taken before and after the 2-week intervention as were sub-maximal responses to the prone Yo-Yo IR1. Internal, external and perceptual responses were collected during SITr/s/SITr, with wellbeing 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, HRR and sub-maximal responses to the prone Yo-Yo IR1 were observed after both interventions. Between-group analysis favoured the SITr/s intervention (trivial to moderate) for changes in 10 m sprint time, CMJ, change of direction and medicine ball throw as well as sub-maximal (280-440 m) high metabolic power, PlayerLoad™ and acceleratory distance during the prone Yo-Yo IR1. Overall changes in wellbeing or neuromuscular function were unclear. Conclusion: Two-weeks of SITr/s and SITr was effective for improving physical characteristics, HRR and sub-maximal responses to the prone Yo-Yo IR1, with no clear change in wellbeing and neuromuscular function. Between-group analysis favoured the SITr/s group, suggesting that the inclusion of sport-specific actions should be considered for in-season conditioning of rugby league players.

Purpose: To assess a standardised testing battery’s ability to differentiate anthropometric and 2 physical qualities between youth, academy and senior rugby league players, and determine the 3 discriminant validity of the battery. 4 Methods: A total of 729 rugby league players from multiple clubs within England categorised 5 as youth (n = 235), academy (n = 362) and senior (n = 132) players completed a standardised 6 testing battery that included the assessment of anthropometric and physical characteristics 7 during preseason. Data was analysed using magnitude-based inferences and discriminant 8 analysis. 9 Results: Academy players were most likely taller and heavier than youth players (effect size 10 (ES) = 0.64 to 1.21), with possibly to most likely superior CMJ, medicine ball throw and prone 11 Yo-Yo IR1 performance (ES = 0.23 to 1.00). Senior players were likely to most likely taller 12 and heavier (ES = 0.32 to 1.84), with possibly to most likely superior 10 and 20 m sprint times, 13 CMJ, CoD, medicine ball throw and prone Yo-Yo IR1 compared to youth and academy (ES = 14 -0.60 to 2.06). The magnitude of difference appeared to be influenced by playing position. For 15 the most part, the battery possessed discriminant validity with an accuracy of 72.2%. 16 Conclusion: The standardised testing battery differentiates anthropometric and physical 17 qualities of youth, academy and senior players as a group and, in most instances, within 18 positional groups. Furthermore, the battery is able to discriminate between playing standards 19 with good accuracy and might be included in future assessments and rugby league talent 20 identification.

Purpose: To investigate the factors affecting the anthropometric and physical characteristics of elite academy rugby league players. Methods: One hundred and ninety-seven elite academy rugby league players (age = 17.3 ± 1.0 years) from five 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 modelling. Results: Associations were observed between several anthropometric and physical characteristics. All physical characteristics improved during preseason and continued to improve until mid-season where thereafter 10 m sprint (η2 = 0.20 cf. 0.25), CMJ (η2 = 0.28 cf. 0.30) and prone Yo-Yo Intermittent Recovery Test (Yo-Yo IR) (η2 = 0.22 cf. 0.54) performance declined. Second (η2 = 0.17) and third (η2 = 0.16) years were heavier than first years, whilst third years had slower 10 m sprint times (η2 = 0.22). Large positional variability was observed for body mass, 20 m sprint time, medicine ball throw, countermovement jump, and prone Yo-Yo IR1. Compared to bottom-ranked teams, top demonstrated superior 20 m (η2 = -0.22) and prone Yo-Yo IR1 (η2 = 0.26) performance whilst middle-ranked teams reported higher CMJ height (η2 = 0.26) and prone Yo-Yo IR1 distance (η2 = 0.20), but slower 20 m sprint times (η2 = 0.20). Conclusion: These findings offer practitioners designing training programmes 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.

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 × 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.

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.