PROLONGED PHYSICAL CONDITIONING AND BLOOD-PLATELET RELEASE MARKERS - A LONGITUDINAL-STUDY

To study the long-term non-acute effect of endurance physical exercise on blood platelet activation, 20 sedentary males and 14 sedentary fem ales were trained 3 to 4 times a week for 9 months. After 24 weeks all subjects ran a 15-km race; and after 36 weeks a half-marathon (21 km) race. Blood samples were drawn before the training programme and 5 da ys after both races. Median (interquartile range) platelet factor 4 an d beta-thromboglobulin pretraining values for the total group were 9 ( 5-35) and 69 (40-495) IU/ml, respectively. During the course of the tr aining programme, plasma platelet factor 4 concentrations rose steadil y and significantly in both the male and female group (p < 0.05), toge ther with a non-significant rise in plasma beta-thromboglobulin. At th e end of the training procedure, 5 days after the half-marathon run, m edian (interquartile range) plasma factor 4 and beta-thromboglobulin c oncentrations for the total group were 150 (62-198) and 156 (84-288) I U/ml, respectively. No difference existed in median platelet factor 4 and beta-thromboglobulin concentrations of the male and female populat ion before or during the training programme. In summary, the results o f this study demonstrate that prolonged physical conditioning of incre asing intensity is mainly associated with an elevation of the platelet protein platelet factor 4.