title: Effect of carbohydrate intake on half-marathon performance of well-trained runners.
abstract: Eighteen highly-trained runners ran two half marathons in mild environmental conditions, 3 wk apart, consuming either 426 +/- 227 mL of a flavored placebo drink (PLACEBO) or an equivalent volume of water (386 +/- 185 mL) and a commercial gel (GEL) supplying 1.1 +/- 0.2 g/kg body mass (BM) carbohydrate (CHO). Voluntary consumption of this fluid was associated with a mean BM change of approximately 2.4%. Runners performed better in their second race by 0.9% or 40 s (P = 0.03). Three runners complained of gastrointestinal discomfort in GEL trial, which produced a clear impairment of half-marathon performance by 2.4% or 105 s (P=0.03). The effect of GEL on performance was trivial: time was improvedby 0.3% or 14 s compared with PLACEBO (P = 0.52). Consuming the gel was associated with a 2.4% slower time through the 2 x 200 m feed zone; adding a trivial approximately 2 s to race time. Although benefits to half marathon performance were not detected, the theoretical improvement during 1-h exercise with CHO intake merits further investigation.
authors.affiliation: Dept of Sports Nutrition, Australian Institute of Sport, Belconnen, ACT, Australia.
authors.forename: Louise M
authors.initials: LM
authors.lastname: Burke
authors.forename: Clare
authors.initials: C
authors.lastname: Wood
authors.forename: David B
authors.initials: DB
authors.lastname: Pyne
authors.forename: D Richard
authors.initials: DR
authors.lastname: Telford
authors.forename: Philo U
authors.initials: PU
authors.lastname: Saunders
mesh_terms: D015746:Abdominal Pain / Q000453:epidemiology; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000009:adverse effects; D004326:Drinking; D005782:Gels; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology; D012420:Running / Q000502:physiology*; D013997:Time Factors
chemical_list: D004040:Dietary Carbohydrates; D005782:Gels