Platelet activation through triathlon competition in ultra-endurance trained athletes: Impact of thrombin and plasmin generation and catecholamine release

The aims of this study were to evaluate whether platelets are activated dur ing strenuous exercise in healthy athletes. Also, to determine the impact o f plasmin and thrombin activity and catecholamine release. Previous studies have shown activation of the hemostatic system after competitive exercise, but platelet activation was thought to be absent in trained athletes. The impact of thrombin and other potent platelet activators is still a matter f or debate. We examined 30 healthy triathletes during a triathlon competitio n. Flow cytometric detection of CD62p (P-selectin) was used to measure in v ivo activation of platelets. Platelet-leukocyte aggregates were also determ ined. Thrombin concentration was assessed by the thrombin-antithrombin III complex (TAT) and the fibrinolytic state was characterised by the plasmin-a lpha (2)-antiplasmin complex (PAP). Catecholamines were measured by means o f high-pressure liquid chromatography. CD62p rose from baseline (2.3 %) to 3.4 % and was still elevated after 2 hours (3.1 %, p = 0.0133). Platelet-le ukocyte aggregates were elevated 30 min after exercise (4.3 % vs 3.6 %) and decreased significantly after 60 min (2.9 %, p = 0.008). TAT increased fro m 3.9 mug/l to 8.3 mug/l after competition and to 5.4 mug/l 2 hours later ( p < 0.001). PAP increased 10-fold from 350 <mu>g/l to 3267 mug/l after the triathlon and was still elevated after 2 hours (1074 mug/l, p < 0.001). No linear correlation was found between the hemostatic markers, catecholamines and platelet activation. Platelets, coagulation and fibrinolysis are activ ated by competitive exercise in athletes, whereby fibrinolytic changes are pronounced. Mechanisms of platelet activation during exercise include pheno mena other than plasmatic hemostatic factors and catecholamines.