We identified the cardiovascular stress encountered by superimposing dehydration on hyperthermia during exercise in the heat and the mechanisms contributing to the dehydration-mediated stroke volume (SV) reduction. Fifteen endurance-trained cyclists [maximal O2 consumption (VO2max) = 4.5 l/min] exercised in the heat for 100-120 min and either became dehydrated by 4% body weight or remained euhydrated [...]

No abstract available.

This study determined the effects of fluid and carbohydrate ingestion on performance, core temperature, and cardiovascular responses during intense exercise lasting 1 h. On four occasions, eight men cycled at 80 +/- 1% (+/- SEM) of VO2max for 50 min followed by a performance test. During exercise, they consumed either a large volume (1330 +/- [...]

To determine the effect an acute plasma volume expansion has on body temperature responses and exercise performance in the heat, seven unacclimatized male volunteers attempted to complete two 90-min walks (45% of VO2 max) in a hot/dry (45 degrees C/20% rh) environment. The experimental walk was preceded by an infusion of human albumin (50 g [...]

Total body water (TBW) and water turnover rates (WTR) of six competitive male cyclists (CG) and six age-matched sedentary men (SG) were determined using deuterium oxide dilution and elimination. During the 7 day study, individuals in the CG cycled daily outside on average 50 (range 12-146) km at an average speed of 29 km.h(-1), while [...]

No abstract available.

Hypohydration reduces exercise performance and thermoregulatory capacity in the heat. Hyperhydration prior to exercise may decrease, delay, or eliminate the detrimental effects of hypohydration. The rapid clearance of excess fluid makes hyperhydration of subjects with common beverages difficult. Glycerol, a natural metabolite which is rapidly absorbed, has osmotic action, and is evenly distributed within the [...]

The present study was prompted by the controversy about the effect of heat-induced dehydration on human performance, and the popular Indian belief that it is not advisable to take water immediately after prolonged exertion in the sun. The points investigated were: (i) the effect of dehydration on some aspects of physical and mental performance, and [...]

The effect of hydration status on performance has not been adequately emphasized or examined in swimmers. Theoretically, moderate overhydration might reduce the proportionate fluid loss from the circulation during exercise of this nature. To explore this issue, 11 (5 women, 6 men) collegiate swimmers swam 2 183-m (200-yd) time trials (3 days apart) in alternate, [...]

No abstract available.