Water versus carbohydrate-electrolyte fluid replacement during loaded marching under heat stress.
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.
Byrne
Christopher
C
Centre for Human Performance, Defence Medical and Environmental Research Institute, DSO National Laboratories, Republic of Singapore.
Lim
Chin Leong
CL
Chew
Serena Ai Neo
SA
Ming
Elaine Tan Yu
ET
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
D001786:Blood Glucose; D007552:Isotonic Solutions; C011259:gatorade; D014867:Water