title: Muscle glycogen utilisation during Rugby match play: Effects of pre-game carbohydrate.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Sixteen (mean±SD age; 18±1 years, body-mass; 88±12kg, height 180±8cm) professional players completed a RL match after 36-h consuming a non-isocaloric high carbohydrate (n=8; 6gkgday-1) or low carbohydrate (n=8; 3gkgday-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±81mmolkg-1d.w.) were unclear. High (243±43mmolkg-1d.w.) and low carbohydrate groups (298±130mmolkg-1d.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±0.39mmoll-1and 1.45±0.51mmoll-1, respectively), whereas differences between the 2 groups for glycerol were unclear (98.1±33.6mmoll-1and 123.1±39.6mmoll-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.
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: James C
authors.initials: JC
authors.lastname: Morehen
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, UK.
authors.forename: Julian
authors.initials: J
authors.lastname: Haigh
authors.affiliation: Widnes Vikings Rugby, UK.
authors.forename: Jon
authors.initials: J
authors.lastname: Clarke
authors.affiliation: Sport and Exercise Sciences, Glyndwr University, UK.
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Donovan
authors.affiliation: Department of Sport and Exercise Sciences, University of Chester, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: Twist
authors.affiliation: Department of Rheumatology, Aintree University Hospital, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Cotton
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: Department of Renal Medicine, Royal Liverpool Hospital, UK.
authors.forename: Asheesh
authors.initials: A
authors.lastname: Sharma
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: Don P M
authors.initials: DP
authors.lastname: Maclaren
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; D000070601:Diet, Carbohydrate Loading; D050528:Diet, Carbohydrate-Restricted; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004734:Energy Metabolism; D005538:Football / Q000502:physiology*; D040362:Geographic Information Systems; D006003:Glycogen / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D006003:Glycogen
keywords: Competition; GPS; Metabolism; Nutrition; Physiology; Team-sport