Abstract des Autors

Time to exhaustion at 87-91% of peak VO2 was measured in 5 untrained men (age: 31+/-8 years, body mass: 74.20+/-16.50 kg, body surface area: 1.90+/-0.24 m**2, peak VO2: 2.87+/-0.40 l/min, plasma volume: 3.21+/-0.88 l; means+/-SD) after consuming nothing (N) or two fluid formulations (10 ml/kg, 743+/-161 ml): Performance 1 (P1), a multi-ionic carbohydrate drink, containing 55 mEq/l Na+, 4.16 g/l citrate, 20.49 g/l glucose, and 365 mOsm/kg H2O, and AstroAde (AA), a sodium chloride-sodium citrate hyperhydration drink, containing 164 mEq/l Na+, 8.54 g/l citrate, <5 mg/l glucose, and 253 mOsm/kg H2O. Mean(+/-SE) endurance for N, P1 and AA was 24.68+/-1.50, 24.55+/-1.09, and 30.50+/-344 min, respectively. Percent changes in plasma volume (PV) from -105 min of rest to zero min before exercise were -1.5+/-3.2% (N), 0.2+/-2.2% (P1), and 4.8+/-3.0% (AA; P<0.05). The attenuated endurance for N and P1 could not be attributed to differences in exercise metabolism (VE, RE, VO2) from the carbohydrate or citrate, terminal heart rate, levels of perceived exertion, forehead or thigh skin blood flow velocity, changes or absolute termination levels of rectal temperature. Thus, the higher level of resting PV for AA just before exercise, as well as greater acid buffering and possibly increased energy substrate from citrate, may have contributed to the greater endurance. Verf.-Referat