• Deteriorations in physical qualities during a 10-week unsupervised off-season period in academy rugby union players

      Twist, Craig; Williams, Jack; Dobbin, Nick; University of Chester; Manchester Metropolitan University
      Purpose: To determine the changes in physical qualities of academy rugby union players over a 10-week unsupervised off-season period. Methods: Body mass, jump height, sprint performance, and intermittent running (30:15 IFT) of 64 academy rugby union players (age = 17.2 ± 0.4 y) were recorded before and after the off-season. Results: Changes in body mass (+1.4 ± 1.3 kg), countermovement jump (-2.2 ± 1.2 cm), squat jump (-1.5 ± 1.8 cm), 10 m sprint (+0.06 ± 0.05 s), 40 m sprint (+0.13 ± 0.11 s) and 30:15 IFT (-0.8 ± 0.8 kmh-1) were observed (P < 0.001, d = -1.77 to 0.47). Only changes in body mass were greater in forwards than backs (P = 0.036, d = 0.46). Players with higher end-of-season body mass, squat jump and 30:15 IFT had greater off-season changes (P = < 0.001 to 0.044; d = 0.63 to 0.94), whilst the pre-post difference in body mass influenced CMJ (P = 0.005, d = 0.75) and 10 m momentum change (P <0.001, d = 1.61). Conclusion: Understanding the individuality of the changes in physical qualities of academy rugby union players during the off-season is important to ensure players return safely to pre-season training loads.
    • 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.
    • Movement characteristics, physiological and perceptual responses of elite standard youth football players to different high intensity running drills

      Gibson, Neil; Henning, Greig; Twist, Craig; Heriot-Watt University; University of Chester (Taylor & Francis, 2018-04-06)
      Purpose: To examine responses to high intensity running drills in youth football players. Methods: Seventeen players completed the YoYo Intermittent Recovery test level one (YYIR1) and a 15 m maximal sprint to quantify target running speeds. Players performed three conditions on separate occasions comprising: 12 x 15 s high intensity runs at 100% of the final YYIRT1 speed, 12 x ~4 s repeated sprints with ~26 s recovery, and combination running using both modalities. Heart rate was monitored continuously with PlayerLoadTM and movement characteristics using microtechnology. Ratings of perceived exertion and blood lactate responses were measured 2 min after the final repetition. The ratio of Flight:contraction time was calculated from a countermovement jump before and at 2 min and 14 hours after each condition. Data analysis used magnitude based inferences and effect sizes statistics. Results: Peak speed (1.1%; ES 0.23 ± 0.44) and mean speed over the initial 4s (6.3%; ES 0.45 ± 0.46) were possibly faster during combination compared to high intensity running with unclear differences when compared to repeated sprinting. This was despite most likely (21.6%; ES 7.65 ± 1.02) differences in prescribed speeds between conditions. There were likely reductions in F:C at 14 hours ratio after high intensity (-5.6%; ES –0.44 ± 0.32) and combination running (-6.8%; ES -0.53 ± 0.47). Changes in the repeated sprinting condition were unclear. Conclusions: Actual movement characteristics of high intensity running drills may not reflect those used to prescribe them whilst reductions in F:C ratio are still evident 14 hours after their completion.
    • Playing exposure does not affect movement characteristics or physiological responses of elite youth footballers during an intensified period of competition.

      Gibson, Neil; McCunn, Robert; MacNay, Sophie; Mullen, Thomas; Twist, Craig; Heriot-Watt University; University of Chester (Taylor & Francis, 2018-05-08)
      This study investigated the effect of playing time on physiological and perceptual responses to six, 60 min matches played over five days. Thirty youth football players (age = 14.1 ± 0.4 years; body mass = 57.4 ± 12.9 kg; stature 169.3 ± 7.7 cm) were grouped into low (<250 min; LPG, n = 18) and high (≥250 min; HPG, n = 12) match exposure groups and monitored daily for lower body power and perceived wellness. GPS technology was used to assess match running demands in total distance (m•min-1), low (<13 km•h-1) and high (≥13 km•h-1) speed running categories. Hypothesis based testing and effect sizes (ES) were used to analyse data. The HPG performed moderately more total distance (103.7 ± 10.4 cf. 90.2 ± 19.7 m•min-1, P = 0.03; ES=0.74 ± 0.63) and high speed running (26.7 ± 6.6 cf. 20.3 ± 6.5 m•min-1, P = 0.01; ES=0.87 ± 0.6) than the LPG across all six matches. Differences of a small magnitude were observed between groups for lower body power (P = 0.08; ES =0.59 ± 0.8) and perceived wellness (P = 0.09; ES=0.42 ± 0.4) which were both higher in the HPG. Youth football players appear well equipped to deal with intensified period of competition, such as those experienced in tournaments, irrespective of match exposure.
    • Pre-season training responses and their associations with training load in elite rugby league players

      Daniels, Matthew; Highton, Jamie M.; Twist, Craig; St Helens RFC; University of Chester (Taylor and Francis, 2019-05-07)
      Strength, power and endurance characteristics and their association with training load during a 7-week preseason training phase was assessed in elite rugby league players. Twenty-two players (age 23.3 ± 4.4 years) performed bench throw, one repetition maximum (1RM) bench press, squat jumps, three repetition maximum (3RM) squats, prone pull ups and prone Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) before and after the 7-week preseason period. Training was classified into Gym, Field and Wrestle, with training load of each monitored using session rating of perceived exertion (sRPE) multiplied by training duration (sRPE-TL). There were most likely improvements in 3RM back squat, prone pull-ups and Yo-Yo IR1 and likely improvements in bench press, bench throw and squat jump after the 7-week training programme (ES = 0.3 to 1.2). Accumulated sRPE-TL for Gym, Field and Wrestle sessions was 9176 ± 1187, 10906 ± 2162, and 1072 ± 315 AU, respectively. Relationships between mean weekly sRPE-TL and changes in physical qualities was trivial to large (r = -0.67 to 0.34). This study suggests sRPE-TL is unsuitable to detect dose-response relationships between training load and the changes in physical qualities of elite rugby league players during the pre-season period.
    • To Infinity and Beyond: The Use of GPS Devices within the Football Codes

      Malone, James; Barrett, Stephen; Barnes, Chris; Twist, Craig; Drust, Barry; Liverpool Hope University; Hull City FC; CB Sports Performance; University of Chester; Liverpool John Moores University (Taylor and Francis, 2019-10-17)
      The quantification of external load through global positioning systems (GPS) is now commonplace across the different football codes. Despite this acceptance amongst sports science practitioners, confusion still remains around which are the most appropriate metrics to use when monitoring their athletes. In addition, the translation of the message between the data gathered and the athletes and coaches can often be lost. The aim of this commentary is to provide discussion and recommendations when using GPS for athlete monitoring.