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Influence of Game Design, Physical Demands, and Skill Involvement on the Subjective Task Load Associated With Various Small-Sided Games Among Elite Junior Rugby League Players

Nick Dobbin, Anthony Atherton, and Colin Hill

Purpose: To determine if small-sided games (SSGs) could be designed to target specific task loads using the National Aeronautics and Space Administration task load index as well as reporting the influence of the physical and technical demands. Methods: Using a within-session, repeated-measures design, 26 junior rugby league players completed 5 SSGs focused on physical, technical, temporal, cognitive, and frustration task loads. National Aeronautics and Space Administration task load index responses were evaluated after each game; the physical demands were recorded using microtechnology; and skill involvement recorded using video analysis. Results: In each SSG, the task load emphasized (eg, physical load/physical game) emerged with a higher score than the other loads and SSGs. The physical demands were lowest during the physical game (effect size = −3.11 to 3.50) and elicited greater defensive involvements (effect size = 0.12 to 3.19). The highest physical demands and attacking involvements were observed during the temporal game. Lower intensity activities were generally negatively associated with physical, performance, temporal, and total load (η 2 = −.07 to −.43) but positively associated with technical, effort, cognitive, and frustration (η 2 = .01 to .33). Distance covered in total and at higher speeds was positively associated with physical, effort, performance, total load (η 2 = .18 to .65), and negatively associated with technical, frustration, and cognitive load (η 2 = −.10 to −.36). Attacking and defensive involvements generally increased the respective task loads (η 2 = .03 to .41). Conclusion: Coaches and sport scientists can design SSGs specifically targeted at subjective task loads in a sport-specific manner and through manipulation of the physical and technical demands.

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Estimates of Energy Intake and Expenditure in Elite Female Touch Players During an International Tournament

Nicola Marsh, Nick Dobbin, Craig Twist, and Chris Curtis

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.

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Sex-Related Changes in Physical Performance, Well-Being, and Neuromuscular Function of Elite Touch Players During a 4-Day International Tournament

Nick Dobbin, Cari Thorpe, Jamie Highton, and Craig Twist

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 (η 2 = −.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.

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The Effects of In-Season, Low-Volume Sprint Interval Training With and Without Sport-Specific Actions on the Physical Characteristics of Elite Academy Rugby League Players

Nick Dobbin, Jamie Highton, Samantha L. Moss, and Craig Twist

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.

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Factors Affecting the Anthropometric and Physical Characteristics of Elite Academy Rugby League Players: A Multiclub Study

Nick Dobbin, Jamie Highton, Samantha Louise Moss, and Craig Twist

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 (η 2 = .20 cf .25), countermovement jump (CMJ) (η 2 = .28 cf .30), and prone Yo-Yo Intermittent Recovery (Yo-Yo IR) test (η 2 = .22 cf .54) performance declined. Second (η 2 = .17) and third (η 2 = .16) -year players were heavier than first-years, whereas third-years had slower 10-m sprint times (η 2 = .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 (η 2 = −.22) and prone Yo-Yo IR1 (η 2 = .26) performance, whereas middle-ranked teams reported higher CMJ height (η 2 = .26) and prone Yo-Yo IR1 distance (η 2 = .20) but slower 20-m sprint times (η 2 = .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.

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The Discriminant Validity of a Standardized Testing Battery and Its Ability to Differentiate Anthropometric and Physical Characteristics Between Youth, Academy, and Senior Professional Rugby League Players

Nick Dobbin, Jamie Highton, Samantha L. Moss, and Craig Twist

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.

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Criterion and Construct Validity of an Isometric Midthigh-Pull Dynamometer for Assessing Whole-Body Strength in Professional Rugby League Players

Nick Dobbin, Richard Hunwicks, Ben Jones, Kevin Till, Jamie Highton, and Craig Twist

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 R 2 = .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 R 2 (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.