Effect of a hydric intake on the rheological properties of blood after a submaximal exercise

Abstract

Ten trained male volunteers have performed a 90 minutes exercise on a Monark ergometer cycle, at 55 % of their maximal aerobic power, during two exercise sessions, one without drinking and the other with a hydric intake (8 ml of water per watt). A blood sample is withdrawn before and after the exercise. Rheological properties have been investigated using viscometry, aggregametry and filtrometry.

A significant increase in hematocrit and plasma protein concentration, as a consequence of hemoconcentration is only observed after the exercise without drinking. The increase in plasma viscosity is more marked after exercise without drinking. At a hematocrit of 45 %, blood viscosities at 1 s⁻¹ and 20 s⁻¹ are significantly increased after the exercise without drinking. After the exercise with drinking, blood viscosity at 20 s⁻¹ remains significantly higher. Blood thixotropy and viscoelasticity are not modified either by the exercise or the hydric intake. Aggregametric and viscometric parameters are significantly impaired after the exercise without drinking but not after the exercise with drinking. Thus, erythrocyte aggregation is only increased after the exercise without drinking in correlation with the increase in fibrinogen. The significant increase in both parameters, viscometric index of deformability (p < 0.005) and filtration viscosity (p < 0.02) after the exercise without drinking indicates a reduced cell deformability. After the exercise with drinking, only the viscometric index of deformability, correlated with the lactate concentration, is significantly higher (p < 0.05). It therefore seems that the hydric intake avoids some of the hemorheological perturbations linked to this type of exercise.