title: The influence of either no fluid or carbohydrate-electrolyte fluid ingestion and the environment (thermoneutral versus hot and humid) on running economy after prolonged, high-intensity exercise.
abstract: This study investigated the effects on running economy (RE) of ingesting either no fluid or an electrolyte solution with or without 6% carbohydrate (counterbalanced design) during 60-min running bouts at 80% maximal oxygen consumption (VO2max). Tests were undertaken in either a thermoneutral (22-23 degrees C; 56-62% relative humidity, RH) or a hot and humid natural environment (Singapore: 25-35 degrees C; 66-77% RH). The subjects were 15 young adult male Singaporeans [VO2max=55.5 (4.4 SD) ml kg(-1) min(-1)]. The RE was measured at 3 m s(-1) [65 (6)% VO2max] before (RE1) and after each prolonged run (RE2). Fluids were administered every 2 min, at an individual rate determined from prior tests, to maintain body mass (group mean=17.4 ml min(-1)). The VO2 during RE2 was higher (P < 0.05) than that during the RE1 test for all treatments, with no differences between treatments (ANOVA). The mean increase in VO2 from RE1 to RE2 ranged from 3.4 to 4.7 ml kg(-1) min(-1) across treatments. In conclusion, the deterioration in RE at 3 m s(-1) (65% VO2max) after 60 min of running at 80% VO2max appears to occur independently of whether fluid is ingested and regardless of whether the fluid contains carbohydrates or electrolytes, in both a thermoneutral and in a hot, humid environment.
authors.affiliation: Chichester Institute of Higher Education, West Sussex, UK.
authors.forename: J
authors.initials: J
authors.lastname: Sproule
mesh_terms: D000328:Adult; D001628:Beverages; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004326:Drinking; D004573:Electrolytes / Q000008:administration & dosage; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D006813:Humidity; D008297:Male; D010100:Oxygen / Q000502:physiology; D012119:Respiration; D012420:Running / Q000502:physiology*; D012964:Sodium / Q000097:blood; D013696:Temperature
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004573:Electrolytes; D012964:Sodium; D010100:Oxygen