Relationships between von Willebrand factor and hemorheology in sportsmen

It is well established that exercise performance in athletes is related to improved blood fluidity. However, training effects on functional state of endothelium and relations of endothelial cell functions with hemorheology are poorly known. Circulating levels of von Willebrand factor may serve as a good marker of endothelial cell functions, its activation, and damage. Relationships between von Willebrand factor antigen (vWf) and blood rheology in 30 endurance sportsmen were investigated. Athletes were divided according to vWf into tertile groups. Compared to 16 controls, all subgroups of sportsmen had a lower erythrocyte rigidity index Tk (p<0.05-0.01), explained by lower values of mean corpuscular hemoglobin concentration (MCHC) (p<0.05-0.01), and a higher W170. The lower tertile group (<0.35 U/ml) had a lower blood viscosity (p<0.05), explained by a lower Tk, and a lower erythrocyte aggregability index (microscopy of diluted blood samples) (p<0.05). The upper tertile group of athletes demonstrated higher levels of plasma viscosity, explained by higher total globulins (p<0.01), and higher vWf levels (p<0.01) than controls, and a lower W170 compared to athletes from the lower tertile subgroup. In the entire group of athletes, log (vWf) was positively correlated to plasma viscosity (r=0.478, p=0.007), total serum globulins (r=0.430, p=0.018), erythrocyte aggregability index (r=0.427, p=0.019), and negatively to log (W170) (r=-0.449, p=0.013). Multiple stepwise regression analysis revealed that plasma viscosity was the primary correlate of vWf. These data shown that the higher von Willebrand level reflecting strong activation of endothelial cells in a part of athletes was closely correlated with increased plasma viscosity levels. We suggest that these hemorheological and endothelial disturbances in these athletes might be a result of exercise overloads.