title: Water versus carbohydrate-electrolyte fluid replacement during loaded marching under heat stress.
abstract: This study compared the effectiveness of carbohydrate-electrolyte (CHO-E) fluid replacement versus water (WAT) on hydration status, physiological and subjective responses, and exercise performance during a 3 x 60-minute loaded (14 kg) treadmill walk in 35 degrees C ambient temperature and 55% humidity. CHO-E did not affect urine loss, plasma volume change (WAT = -3.0 +/- 1.6% vs. CHO-E = -1.1 +/- 1.6%), dehydration (WAT = 0.4 +/- 0.3% vs. CHO-E = 0.4 +/- 0.3% of body mass), or core body temperature (Tc) and heart rate (HR) responses. Endurance time was greater but not significantly different with CHO-E (WAT = 134 +/- 9 vs. CHO-E = 146 +/- 9 minutes). CHO-E increased the frequency of task completion (WAT = 21% vs. CHO-E = 50%), elevated blood glucose, and reduced perceived exertion. CHO-E offers potential to enhance exercise capacity by elevating blood glucose and thereby preventing hypoglycemia, maintaining high rates of carbohydrate oxidation, and/or preventing central fatigue; but provided no additional benefits with regard to hydration status and physiological function during loaded walking under heat stress.
authors.affiliation: Centre for Human Performance, Defence Medical and Environmental Research Institute, DSO National Laboratories, Republic of Singapore.
authors.forename: Christopher
authors.initials: C
authors.lastname: Byrne
authors.forename: Chin Leong
authors.initials: CL
authors.lastname: Lim
authors.forename: Serena Ai Neo
authors.initials: SA
authors.lastname: Chew
authors.forename: Elaine Tan Yu
authors.initials: ET
authors.lastname: Ming
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D018592:Cross-Over Studies; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006801:Humans; D007552:Isotonic Solutions / Q000008:administration & dosage*; D008297:Male; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D012846:Singapore; D016896:Treatment Outcome; D016138:Walking / Q000502:physiology*; D014867:Water / Q000008:administration & dosage*; D014882:Water-Electrolyte Balance
chemical_list: D001786:Blood Glucose; D007552:Isotonic Solutions; C011259:gatorade; D014867:Water