title: Effect of water ingestion on endurance capacity during prolonged running.
abstract: This study examined the influence of water ingestion on endurance capacity during submaximal treadmill running. Four men and four women with a mean (+/-S.E.) age of 21.4 +/- 0.7 years, height of 169 +/- 2 cm, body mass of 63.1 +/- 2.9 kg and VO2 max of 51.1 +/- 1.8 ml kg-1 min-1, performed two randomly assigned treadmill runs at 70% VO2 max to exhaustion. No fluid was ingested during one trial (NF-trial), whereas a single water bolus of 3.0 ml kg-1 body mass was ingested immediately pre-exercise and serial feedings of 2.0 ml kg-1 body mass were ingested every 15 min during exercise in a fluid replacement trial (FR-trial). Run time for the NF-trial was 77.7 +/- 7.7 min, compared to 103 +/- 12.4 min for the FR-trial (P < 0.01). Body mass (corrected for water ingestion) decreased by 2.0 +/- 0.2% in the NF-trial and 2.7 +/- 0.2% in the FR-trial (P < 0.01), while plasma volume decreased by 1.1 +/- 1.1% and 3.5 +/- 1.1% in the two trials respectively (N.S.). However, these apparent differences in circulatory volume were not associated with differences in rectal temperature. Respiratory exchange ratios indicated increased carbohydrate metabolism (73% vs 64% of total energy expenditure) and suppressed fat metabolism after 75 min of exercise in the NF-trial compared with the FR-trial (NF-trial, 0.90 +/- 0.01; FR-trial, 0.86 +/- 0.03; P < 0.01). Blood glucose concentrations were similar in both trials, while blood lactate concentrations were higher in the NF-trial at the end of exercise (4.83 +/- 0.34 vs 4.18 +/- 0.38 mM; P < 0.05). In summary, water ingestion during prolonged running improved endurance capacity.
authors.affiliation: School of Sports Studies, Faculty of Science, Chichester Institute of Higher Education, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Fallowfield
authors.forename: C
authors.initials: C
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Booth
authors.forename: B H
authors.initials: BH
authors.lastname: Choo
authors.forename: S
authors.initials: S
authors.lastname: Growns
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004326:Drinking; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid