• The assessment of total energy expenditure during a 14-day ‘in-season’ period of professional rugby league players using the Doubly Labelled Water method

      Morehen, James C.; Bradley, Warren J.; Clarke, Jon; Twist, Craig; Hambly, Catherine; Speakman, John R.; Morton, James P.; Close, Graeme L.; Liverpool John Moores University; Widnes Vikings Rugby League; University of Chester; University of Aberdeen (Human Kinetics, 2016-10-31)
      Rugby League is a high-intensity collision sport competed over 80-minutes. Training loads are monitored to maximise recovery and assist in the design of nutritional strategies although no data are available on the Total Energy Expenditure (TEE) of players. We therefore assessed Resting Metabolic Rate (RMR) and TEE in six Super-League players over two consecutive weeks in-season including one-game per week. Fasted RMR was assessed followed by a baseline urine sample before oral administration of a bolus dose of hydrogen (deuterium 2H) and oxygen (18O) stable isotopes in the form of water (2H218O). Every 24 hours thereafter, players provided urine for analysis of TEE via DLW method. Individual training-load was quantified using session rating of perceived exertion (sRPE) and data were analysed using magnitude-based inferences. There were unclear differences in RMR between forwards and backs (7.7 ± 0.5 cf. 8.0 ± 0.3 MJ, respectively). Indirect calorimetry produced RMR values most likely lower than predictive equations (7.9 ± 0.4 cf. 9.2 ± 0.4 MJ, respectively). A most likely increase in TEE from week-1 to -2 was observed (17.9 ± 2.1 cf. 24.2 ± 3.4 MJ) explained by a most likely increase in weekly sRPE (432 ± 19 cf. 555 ± 22 AU), respectively. The difference in TEE between forwards and backs was unclear (21.6 ± 4.2 cf. 20.5 ± 4.9 MJ, respectively). We report greater TEE than previously reported in rugby that could be explained by the ability of DLW to account for all match and training-related activities that contributes to TEE.
    • Carbohydrate and caffeine improves high intensity running of elite rugby league interchange players during simulated match play

      Clarke, Jon; Highton, Jamie M.; Close, Graeme L.; Twist, Craig; University of Chester; Warrington Wolves RLFC; Liverpool John Moores University (Lippincott, Williams & Wilkins, 2016-11-19)
      Carbohydrate and caffeine improves high intensity running of elite rugby league interchange players during simulated match play
    • Energy intake and expenditure assessed ‘in-season’ in an elite European rugby union squad.

      Bradley, Warren J.; Cavanagh, Bryce; Douglas, William; Donovan, Timothy F.; Twist, Craig; Morton, James P.; Close, Graeme L. (2015-06-09)
      Rugby union (RU) is a complex high-intensity intermittent collision sport with emphasis placed on players possessing high lean body mass and low body fat. After an 8 to 12-week pre-season focused on physiological adaptations, emphasis shifts towards competitive performance. However, there are no objective data on the physiological demands or energy intake (EI) and energy expenditure (EE) for elite players during this period. Accordingly, in-season training load using global positioning system and session rating of perceived exertion (sRPE), alongside six-day assessments of EE and EI were measured in 44 elite RU players. Mean weekly distance covered was 7827 ± 954 m and 9572 ± 1233 m with a total mean weekly sRPE of 1776 ± 355 and 1523 ± 434 AU for forwards and backs, respectively. Mean weekly EI was 16.6 ± 1.5 and 14.2 ± 1.2 megajoules (MJ) and EE was 15.9 ± 0.5 and 14 ± 0.5 MJ. Mean carbohydrate (CHO) intake was 3.5 ± 0.8 and 3.4 ± 0.7 g.kg-1 body mass, protein intake was 2.7 ± 0.3 and 2.7 ± 0.5 g.kg-1 body mass, and fat intake was 1.4 ± 0.2 and 1.4 ± 0.3 g.kg-1 body mass. All players who completed the food diary self-selected a 'low' CHO 'high' protein diet during the early part of the week, with CHO intake increasing in the days leading up to a match, resulting in the mean EI matching EE. Based on EE and training load data, the EI and composition seems appropriate, although further research is required to evaluate if this diet is optimal for match day performance.
    • Exercise-induced muscle damage: what is it, what causes it and what are the nutritional solutions?

      Owens, Daniel J.; Twist, Craig; Cobley, James; Howatson, Glyn; Close, Graeme L.; Liverpool John Moores University; University of Chester; Northumbria University (Taylor & Francis, 2018-08-15)
      Exercise-induced muscle damage (EIMD) is characterised by symptoms that present both immediately and for up to 14 days after the initial exercise bout. The main consequence of EIMD for the athlete is the loss of skeletal muscle function and soreness. As such, numerous nutrients and functional foods have been examined for their potential to ameliorate the effects of EIMD and accelerate recovery, which is the purpose of many nutritional strategies for the athlete. However, the trade-off between recovery and adaptation is rarely considered. For example, many nutritional interventions described in this review target oxidative stress and inflammation, both thought to contribute to EIMD but are also crucial for the recovery and adaptation process. This calls into question whether long term administration of supplements and functional foods used to target EIMD is indeed best practice. This rapidly growing area of sports nutrition will benefit from careful consideration of the potential hormetic effect of long term use of nutritional aids that ameliorate muscle damage. This review provides a concise overview of what EIMD is, its causes and consequences and critically evaluates potential nutritional strategies to ameliorate EIMD. We present a pragmatic practical summary that can be adopted by practitioners and direct future research, with the purpose of pushing the field to better consider the fine balance between recovery and adaptation and the potential that nutritional interventions have in modulating this balance.
    • Metabolic demands and replenishment of muscle glycogen after a rugby league match simulation protocol.

      Bradley, Warren J.; Hannon, Marcus P.; Benford, Victoria; Morehen, James C.; Twist, Craig; Shepherd, Sam; Cocks, Matthew; Impey, Samuel G.; Cooper, Robert G.; Morton, James P.; et al. (2017-02-22)
      Objectives: The metabolic requirements of a rugby league match simulation protocol and the timing of carbohydrate provision on glycogen re-synthesis in damaged muscle were examined. Design: Fifteen (mean ± SD: age 20.9 ± 2.9 y, body-mass 87.3 ± 14.1 kg, height 177.4 ± 6.0 cm) rugby league (RL) players consumed a 6 g•kg•day-1 CHO diet for 7-days, completed a time to exhaustion test (TTE) and a glycogen depletion protocol on day-3, a RL simulated-match protocol (RLMSP) on day-5 and a TTE on day-7. Players were prescribed an immediate or delayed (2-h-post) re-feed post-simulation. Methods: Muscle biopsies and blood samples were obtained post-depletion, before and after simulated match-play, and 48-h after match-play with PlayerLoad and heart-rate collected throughout the simulation. Data were analysed using effects sizes ± 90% CI and magnitude-based inferences. Results: PlayerLoad (8.0 ± 0.7 AU•min-1) and %HRpeak (83 ± 4.9%) during the simulation were similar to values reported for RL match-play. Muscle glycogen very likely increased from immediately after to 48-h post-simulation (272 ± 97 cf. 416 ± 162 mmol•kg-1d.w.; ES ± 90%CI) after immediate re-feed, but changes were unclear (283 ± 68 cf. 361 ± 144 mmol•kg-1d.w.; ES ± 90%CI) after delayed re-feed. CK almost certainly increased by 77.9 ± 25.4% (0.75 ± 0.19) post-simulation for all players. Conclusions: The RLMSP presents a replication of the internal loads associated with professional RL match-play, although difficulties in replicating the collision reduced the metabolic demands and glycogen utilisation. Further, it is possible to replete muscle glycogen in damaged muscle employing an immediate re-feed strategy.
    • Muscle glycogen utilisation during Rugby match play: Effects of pre-game carbohydrate

      Bradley, Warren J.; Morehen, James C.; Haigh, Julian; Clarke, Jon; Donovan, Timothy F.; Twist, Craig; Cotton, Caroline; Shepherd, Sam; Cocks, Matthew; Sharma, Asheesh; et al. (Elsevier, 2016-04-22)
      Objectives: Although the physical demands of Rugby League (RL) match-play are well-known, the fuel sources supporting energy-production are poorly understood. We therefore assessed muscle glycogen utilisation and plasma metabolite responses to RL match-play after a relatively high (HCHO) or relatively low CHO (LCHO) diet. Design: Sixteen (mean ± SD age; 18 ± 1 years, body-mass; 88 ± 12 kg, height 180 ± 8 cm) professional players completed a RL match after 36-h consuming a non-isocaloric high carbohydrate (n = 8; 6 g kg day−1) or low carbohydrate (n = 8; 3 g kg day−1) diet. Methods: Muscle biopsies and blood samples were obtained pre- and post-match, alongside external and internal loads quantified using Global Positioning System technology and heart rate, respectively. Data were analysed using effects sizes ±90% CI and magnitude-based inferences. Results: Differences in pre-match muscle glycogen between high and low carbohydrate conditions (449 ± 51 and 444 ± 81 mmol kg−1 d.w.) were unclear. High (243 ± 43 mmol kg−1 d.w.) and low carbohydrate groups (298 ± 130 mmol kg−1 d.w.) were most and very likely reduced post-match, respectively. For both groups, differences in pre-match NEFA and glycerol were unclear, with a most likely increase in NEFA and glycerol post-match. NEFA was likely lower in the high compared with low carbohydrate group post-match (0.95 ± 0.39 mmol l−1 and 1.45 ± 0.51 mmol l−1, respectively), whereas differences between the 2 groups for glycerol were unclear (98.1 ± 33.6 mmol l−1 and 123.1 ± 39.6 mmol l−1) in the high and low carbohydrate groups, respectively. Conclusions: Professional RL players can utilise ∼40% of their muscle glycogen during a competitive match regardless of their carbohydrate consumption in the preceding 36-h.
    • Player responses to match and training demands during an intensified fixture schedule in professional rugby league: A case study.

      Twist, Craig; Highton, Jamie M.; Daniels, Matthew; Mill, Nathan; Close, Graeme L.; University of Chester; St Helens RFC; Liverpool John Moores (Human Kinetics, 2017-09-30)
      Player loads and fatigue responses are reported in 15 professional rugby league players (24.3 ± 3.8 y) during a period of intensified fixtures. Repeated measures of internal and external loads, perceived well-being, and jump flight time were recorded across 22 d, comprising 9 training sessions and matches on days 5, 12, 15, and 21 (player exposure: 3.6 ± 0.6 matches). Mean training loads (session rating of perceived exertion × duration) between matches were 1177, 1083, 103, and 650 AU. Relative distance in match 1 (82 m/min) and match 4 (79 m/min) was very likely lower in match 2 (76 m/min) and likely higher in match 3 (86 m/min). High-intensity running (≥5.5 m/s) was likely to very likely lower than match 1 (5 m/min) in matches 2–4 (2, 4, and 3 m/min, respectively). Low-intensity activity was likely to very likely lower than match 1 (78 m/min) in match 2 (74 m/min) and match 4 (73 m/min) but likely higher in match 3 (81 m/min). Accumulated accelerometer loads for matches 1–4 were 384, 473, 373, and 391 AU, respectively. Perceived well-being returned to baseline values (~21 AU) before all matches but was very likely to most likely lower the day after each match (~17 AU). Prematch jump flight times were likely to most likely lower across the period, with mean values of 0.66, 0.65, 0.62, and 0.64 s before matches 1–4, respectively. Across a 22-d cycle with fixture congestion, professional rugby league players experience cumulative neuromuscular fatigue and impaired match running performance.
    • Position specific differences in the anthropometric characteristics of elite European Super League rugby players

      Morehen, James C.; Routledge, Harry E.; Twist, Craig; Morton, James P.; Close, Graeme L.; Liverpool John Moores University; University of Chester (Routledge, 2015-01-05)
    • Season-long increases in perceived muscle soreness in professional rugby league players: role of player position, match characteristics and playing surface

      Fletcher, Ben D.; Twist, Craig; Haigh, Julian; Brewer, Clive; Morton, James P.; Close, Graeme L.; Liverpool John Moores University; University of Chester (Taylor and Francis, 2015-09-14)
      Rugby League (RL) is a high-impact collision sport characterised by repeated sprints and numerous high-speed impacts and consequently players often report immediate and prolonged muscle soreness in the days after a match. We examined muscle soreness after matches during a full season to understand the extent to which match characteristics influence soreness. Thirty-one elite Super League players provided daily measures of muscle soreness after each of the 26 competitive fixtures of the 2012 season. Playing position, phase of the season, playing surface and match characteristics were recorded from each match. Muscle soreness peaked at day 1 and was still apparent at day 4 post-game with no attenuation in the magnitude of muscle soreness over the course of the season. Neither playing position, phase of season or playing surface had any effects on the extent of muscle soreness. Playing time and total number of collisions were significantly correlated with higher ratings of muscle soreness, especially in the forwards. These data indicate the absence of a repeated bout effect or ‘contact adaptations’ in elite rugby players with soreness present throughout the entire season. Strategies must now be implemented to deal with the physical and psychological consequences of prolonged feeling of pain