title: Metabolic demands and replenishment of muscle glycogen after a rugby league match simulation protocol.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Fifteen (mean±SD: age 20.9±2.9 year, body-mass 87.3±14.1kg, height 177.4±6.0cm) rugby league (RL) players consumed a 6gkgday-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 AUmin-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±162mmolkg-1d.w.; ES±90%CI) after immediate re-feed, but changes were unclear (283±68 cf. 361±144mmolkg-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.
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Bradley
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Marcus P
authors.initials: MP
authors.lastname: Hannon
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Victoria
authors.initials: V
authors.lastname: Benford
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: James C
authors.initials: JC
authors.lastname: Morehen
authors.affiliation: Department of Sport and Exercise Sciences, University of Chester, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: Twist
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Sam
authors.initials: S
authors.lastname: Shepherd
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Cocks
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Impey
authors.affiliation: MRC Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing, University of Liverpool, UK.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Cooper
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: James P
authors.initials: JP
authors.lastname: Morton
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK. Electronic address: g.l.close@ljmu.ac.uk.
authors.forename: Graeme L
authors.initials: GL
authors.lastname: Close
mesh_terms: D000293:Adolescent; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology; D004040:Dietary Carbohydrates; D005080:Exercise Test; D005538:Football / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism*; D006339:Heart Rate; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D064133:Sports Nutritional Physiological Phenomena; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D006003:Glycogen
keywords: Carbohydrate; Contact; Metabolism; Nutrition; Physiology; Team-sport