title: Pre-exercise hyperhydration-induced bodyweight gain does not alter prolonged treadmill running time-trial performance in warm ambient conditions.
abstract: This study compared the effect of pre-exercise hyperhydration (PEH) and pre-exercise euhydration (PEE) upon treadmill running time-trial (TT) performance in the heat. Six highly trained runners or triathletes underwent two 18 km TT runs (~28 °C, 25%-30% RH) on a motorized treadmill, in a randomized, crossover fashion, while being euhydrated or after hyperhydration with 26 mL/kg bodyweight (BW) of a 130 mmol/L sodium solution. Subjects then ran four successive 4.5 km blocks alternating between 2.5 km at 1% and 2 km at 6% gradient, while drinking a total of 7 mL/kg BW of a 6% sports drink solution (Gatorade, USA). PEH increased BW by 1.00 ± 0.34 kg (P < 0.01) and, compared with PEE, reduced BW loss from 3.1% ± 0.3% (EUH) to 1.4% ± 0.4% (HYP) (P < 0.01) during exercise. Running TT time did not differ between groups (PEH: 85.6 ± 11.6 min; PEE: 85.3 ± 9.6 min, P = 0.82). Heart rate (5 ± 1 beats/min) and rectal (0.3 ± 0.1 °C) and body (0.2 ± 0.1 °C) temperatures of PEE were higher than those of PEH (P < 0.05). There was no significant difference in abdominal discomfort and perceived exertion or heat stress between groups. Our results suggest that pre-exercise sodium-induced hyperhydration of a magnitude of 1 L does not alter 80-90 min running TT performance under warm conditions in highly-trained runners drinking ~500 mL sports drink during exercise.
authors.affiliation: Research Centre on Aging, University of Sherbrooke, Sherbrooke, Canada. Pierre-Yves.Gigou@usherbrooke.ca
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Gigou
authors.forename: Tommy
authors.initials: T
authors.lastname: Dion
authors.forename: Audrey
authors.initials: A
authors.lastname: Asselin
authors.forename: Felix
authors.initials: F
authors.lastname: Berrigan
authors.forename: Eric D B
authors.initials: ED
authors.lastname: Goulet
mesh_terms: D000328:Adult; D001831:Body Temperature; D018592:Cross-Over Studies; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D007552:Isotonic Solutions / Q000008:administration & dosage*; D008297:Male; D012420:Running / Q000502:physiology*; D055815:Young Adult
chemical_list: D007552:Isotonic Solutions; C011259:gatorade