RehydrationChanges in plasma volume and blood viscosity during a 4-hour period sitting in a dry environment: The effects of prehydration
Doi T, Sakurai M, Hamada K, Matsumoto K, Yanagisawa K, Kikuchi N, Morimoto T,
Aviat Space Environ Med 2004; 75: 500-504
We examined our hypothesis that prehydration with an ion supply drink would be better than prehydration with water for maintaining the body fluid balance and preventing increased blood viscosity during a four-hour period spent sitting in a dry environment.
Twelve healthy male subjects were studied in three randomized cross-over intervention trials of prehydration using an ion supply drink, water, or a control condition with no prehydration. For each trial, subjects sat for four hours in an environment with an ambient temperature of 23.0-23.5℃ and a relative humidity of 18-36%. They consumed 6 mL/kg body weight of test beverage at the start of 4-hour period. The plasma volume and blood viscosity were measured every hour. The urine volume and body weight were recorded at two and four hours.
The retention of the consumed fluid was significantly higher for the ion supply drink group than for water during the first two hours. The plasma volume decreased and the blood viscosity increased when there was no prehydration. The plasma volume for the ion supply drink group was maintained at the baseline level in comparison to the water group at two hours. The increase in blood viscosity for the participants in the ion supply drink group was maintained at the baseline level which was significantly lower than the no prehydration group at 2-3 hours.
An ion supply drink may be useful for maintaining the body fluid balance and preventing an increase in blood viscosity during prolonged sitting in a dry environment.
Changes in plasma volume, blood viscosity
during 4 hours of sitting
Fluid retention during the first 2 hours of sitting
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