The effect of exercise on blood fluidity: Use of the capillary model to assess the clogginess of blood.

Abstract

The goal was to evaluate the effects of exercise on the clogginess of blood as well as the effect of increased blood cell count and hematocrit levels after exercise. We also investigated the mechanisms underlying the clogginess of blood. The time required for blood to pass through microchannels was measured. We focused on assessing the consecutive passage times for serial 20 μL volumes. We used heparinized peripheral blood obtained from subjects after exercise conducted at three intensity levels. Blood samples were also adjusted to achieve specific hematocrit levels or supplemented by addition of adenosine diphosphate (ADP). The sequential blood passage times of consecutive 20 μL volumes increased with platelet aggregation and adhesion of white blood cells (WBC). We also observed an increase with blood cell counts and hematocrit levels. These changes occurred after high intensity exercise but not after low or medium intensity exercise. Furthermore, the sequential blood passage times of 20 μL volumes increased with platelet aggregation and adhesion of WBC at an ADP concentration at the threshold of aggregation but not at higher levels of hematocrit. These findings suggested that high intensity exercise might induce the clogginess of blood by enhanced platelet aggregation and adhesion of WBC.