title: Effects of carbohydrate-hydration strategies on glucose metabolism, sprint performance and hydration during a soccer match simulation in recreational players.
abstract: OBJECTIVE
  This study compared the effects of three carbohydrate-hydration strategies on blood glucose concentration, exercise performance and hydration status throughout simulated soccer match-play.
  
  
  METHODS
  A randomized, double-blind and cross-over study design was employed.
  
  
  METHODS
  After familiarization, 14 recreational soccer players completed the soccer match simulation on three separate occasions. Participants consumed equal volumes of 9.6% carbohydrate-caffeine-electrolyte (∼ 6 mg/kg BW caffeine) solution with carbohydrate-electrolyte gels (H-CHO), 5.6% carbohydrate-electrolyte solution with electrolyte gels (CHO) or electrolyte solution and electrolyte gels (PL). Blood samples were taken at rest, immediately before exercise and every 15 min during exercise (first half: 15, 30, 45 min; second half: 60, 75, 90 min).
  
  
  RESULTS
  Supplementation influenced blood glucose concentration (time × treatment interaction: p<0.001); however, none of the supplementation regimes were effective in preventing a drop in blood glucose at 60 min. Mean sprint speed was 3 ± 1% faster in H-CHO when compared with PL (treatment: p=0.047). Supplementation caused a 2.3 ± 0.5% increase in plasma osmolality in H-CHO (p<0.001) without change in CHO or PL. Similarly, mean sodium concentrations were 2.1 ± 0.4% higher in H-CHO when compared with PL (p=0.006).
  
  
  CONCLUSIONS
  Combining high carbohydrate availability with caffeine resulted in improved sprint performance and elevated blood glucose concentrations throughout the first half and at 90 min of exercise; however, this supplementation strategy negatively influenced hydration status when compared with 5.6% carbohydrate-electrolyte and electrolyte solutions.
authors.affiliation: Exercise Physiology, La Trobe Rural Health School, La Trobe University, Australia; Sport and Exercise Science, Engineering, Swansea University, UK. Electronic address: m.kingsley@latrobe.edu.au.
authors.forename: Michael
authors.initials: M
authors.lastname: Kingsley
authors.affiliation: Nutrition and Bromatology, Pharmacy, Universidad Complutense de Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Penas-Ruiz
authors.affiliation: Sport and Exercise Science, Engineering, Swansea University, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Terry
authors.affiliation: Sport and Exercise Sciences, Northumbria University, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Russell
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001628:Beverages; D001786:Blood Glucose / Q000378:metabolism*; D002110:Caffeine / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000097:blood; D019587:Dietary Supplements; D004311:Double-Blind Method; D004573:Electrolytes / Q000008:administration & dosage* / Q000097:blood; D006801:Humans; D009994:Osmolar Concentration; D005082:Physical Exertion / Q000502:physiology; D012420:Running / Q000502:physiology; D012916:Soccer / Q000502:physiology*; D012964:Sodium / Q000097:blood; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004573:Electrolytes; D002110:Caffeine; D012964:Sodium
keywords: Football; Rebound hypoglycemia; Shooting; Supplementation