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Blood viscosity after a 1-h submaximal exercise with and without drinking
H Vandewalle1, C Lacombe, J C Lelièvre
1Unité de Biorhéologie (C.N.R.S. UA 343), Université de Paris, France.
International Journal of Sports Medicine
|April 1, 1988
Summary
Drinking during endurance exercise partially attenuated blood viscosity increases by counteracting hemoconcentration. However, significant increases in hematocrit and plasma viscosity still occurred, suggesting capillary leakage also contributes to dehydration during intense exercise.
Area of Science:
- Exercise Physiology
- Sports Science
- Cardiovascular Health
Background:
- Endurance exercise increases blood viscosity due to hemoconcentration.
- Fluid intake during exercise may mitigate these hemoconcentration effects.
Purpose of the Study:
- To investigate if compensating for sweat loss by drinking attenuates exercise-induced increases in blood viscosity.
- To explore the role of hemoconcentration and potential capillary leakage in exercise-induced blood changes.
Main Methods:
- Ten healthy subjects completed two cycling exercise sessions at 85% maximal heart rate.
- Session 1: No fluid intake. Session 2: Fluid intake equal to weight loss from Session 1.
- Measurements included hematocrit, plasma viscosity, whole blood viscosity, and hemoconcentration.
Main Results:
- Both protocols significantly increased hematocrit and plasma viscosity.
- Whole blood viscosity increased significantly only in the no-drinking protocol.
- Drinking partially attenuated the increase in blood viscosity, but did not fully prevent it.
Conclusions:
- Fluid intake can partially offset exercise-induced hemoconcentration and blood viscosity changes.
- Capillary leakage, in addition to sweat loss, likely contributes to hemoconcentration during intense exercise.
- Further research is needed to fully understand the mechanisms behind exercise-induced hemoconcentration.