Glucose polymer ingestion--effect on fluid balance and glycemic state during a 4-d march

The effect of glucose-polymer solution on physical performance has been extensively studied under controlled laboratory conditions. The present study was conducted to investigate the influence of such beverages on fluid balance and on glycemic state during a moderate, prolonged field exercise. Forty-eight endurance trained, male subjects participated in the study. The maneuver consisted of a 4-d march; 29, 39, 36, 30 km.d-1, at a speed of 5-6 km.h-1. The subjects covered a total distance of 134 km at an estimated exercise intensity of approximately 40% VO2max, under hot climate conditions (ambient temperature, 32-41 degrees C; relative humidity, 60-14%). Subjects were randomly assigned to one of two groups: glucose polymer-electrolyte beverage (GP; N = 24) and tap water (TW; N = 24). Each group was then divided into two subgroups consuming fluid ad libitum (TWa, GPa) or instructed to consume 900 ml.h-1 (TWb, GPb). The mean daily fluid consumption of all subgroups was similar (5252 +/- 229 and 4640 +/- 67 ml in TWa and TWb; 5257 +/- 317 and 5253 +/- 216 ml in GPa and GPb, respectively). Weight loss, reflecting the degree of dehydration, was 1.2 +/- 0.1% and 1.9 +/- 0.3% of initial body weight in TW and GP, respectively. On day 1, plasma volume changed by +0.4% and -1.8% in the TW and GP groups, respectively. On the days 2-4 changes in both groups were similar.(ABSTRACT TRUNCATED AT 250 WORDS)