• Development of anthropometric characteristics in professional Rugby League players: Is there too much emphasis on the pre-season period?

      Morehen, James; Clarke, Jon; Batsford, Jake; Highton, Jamie; Erskine, Robert; Morton, James; Close, Graeme
      Rugby League is a team sport requiring players to experience large impact collisions, thus requiring high amounts of muscle mass. Many players (academy and senior) strive to increase muscle mass during the pre-season, however, quantification of changes during this period have not been thoroughly investigated. We therefore assessed changes in body-composition using Dual X-Ray Absorptiometry (DXA) in eleven academy players over three successive pre-seasons and ninety-three senior players from four different European Super League clubs prior to, and at the end of, a pre-season training period. There was no meaningful change in lean mass of the academy players during any of the pre-season periods (year 1 = 72.3 ± 7.1–73.2 ± 7.2kg; ES 0.05, year 2 = 74.4 ± 6.9–75.5 ± 6.9kg; ES 0.07, year 3 = 75.9 ± 6.7–76.8 ± 6.6kg; ES 0.06) with small changes only occurring over the three-year study period (72.3–75.9kg; ES = 0.22). Senior players showed trivial changes in all characteristics during the pre-season period (total mass = 95.1–95.0kg; ES −0.01, lean mass = 74.6–75.1kg; ES 0.07, fat mass = 13.6–12.9kg; ES −0.17, body fat percentage = 14.8–14.1%; ES −0.19). These data suggest that academy players need time to develop towards profiles congruent with senior players. Moreover, once players reach senior level, body-composition changes are trivial during the pre-season and therefore teams may need to individualise training for players striving to gain muscle mass by reducing other training loads.
    • Influence of contextual factors, technical performance and movement demands on the subjective task load associated with professional rugby league match-play

      Mullen, Thomas; Twist, Craig; Daniels, Matthew; Dobbin, Nick; Highton, Jamie; University of Chester
      Purpose: The aim of the study was 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, culminating in 441 individual data points. Linear mixed-modelling was adopted to analyze the data for relationships and 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% CI; η2= 0.18 ±0.11), errors (η2= 0.15 ±0.08) decelerations (η2= 0.12 ±0.08), increased sprint distance (η2= 0.13 ±0.08), losing matches (η2= 0.36 ±0.08) and increased perception of effort (η2= 0.27 ±0.08) 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 the number of technical errors (η2= 0.10 ±0.08). 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 the prescription of recovery sessions and current training practices.
    • The influence of warm-up duration on simulated rugby league interchange match performance

      Williams, Robert; Gillham, Scott; Highton, Jamie; Twist, Craig; University of Chester (Taylor & Francis, 2020-09-10)
      Objective: The study was conducted to understand the effects of a short (10-minute) and a long (30-minute) duration warm-up on subsequent readiness to exercise and movement during simulated rugby league match play. Methods: Using a randomised cross-over design, 13 male rugby players (age: 23.6 ± 4.1 y) completed a 10- or 30-minute warm-up immediately before 2 x 23 min rugby league movement simulation protocol. Comparisons of the responses to the warm-up and during the simulation were made between each trial. Results: Total distance, high- and low speed running and tympanic temperature (ES = 0.56 to 20.8) were all higher in the 30 min warm-up, with differences in relative distance and heart rate unclear (ES = -0.36 to 0.06). Differences in participants’ readiness to exercise after the warm-ups were unclear (ES = 0.25). Differences between trials for movement characteristics (ES = -0.13 to -0.32), RPE (ES = -0.13 to 0.04) and B[La] after the simulation were mostly unclear, with only trivial changes in high-speed running (ES = 0.08) and a lower heart rate (ES = -0.26) between the two playing bouts after the 30 min warm-up trial. Conclusion: Practitioners can use warm-ups between 10 or 30 minutes for rugby league interchange players without any implications for subsequent match running performance.
    • The physiological and perceptual effects of stochastic simulated rugby league match play

      Mullen, Thomas; Twist, Craig; Highton, Jamie; University of Chester
      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 two trials (randomised and control) of a rugby league movement simulation protocol, separated by 7-10 days. The control trial (CON) 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, RPE and Stroop test performance were assessed throughout. MVC peak torque, voluntary activation (%) 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 RPE (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). MVC peak torque (CON = -48.4 ± 31.6 N∙m, STOCH = -39.6 ± 36.6 N∙m) and voluntary activation (CON = -8.3 ± 4.8%, 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.
    • Stochastic ordering of simulated rugby match activity produces reliable movements and associated measures of subjective task load, cognitive and neuromuscular function

      Mullen, Thomas; Twist, Craig; Highton, Jamie; University of Chester (Taylor and Francis, 2019-07-31)
      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.