Evidence for Prothrombotic Effects of Exercise and Limited Protection by Aspirin

Abstract

Background—Exercise may activate platelets and leukocytes and promote thrombosis. The effects of aspirin treatment on the prothrombotic effects of exercise have not been established. Methods and Results—A total of 15 healthy men performed exhaustive exercise without and with 1 week of pretreatment with aspirin (500 mg/day). Before and immediately after exercise, platelet aggregability ex vivo was measured by filtragometry, and venous blood samples were obtained. Whole-blood flow cytometry was used to determine platelet and leukocyte activation and platelet-leukocyte aggregates. Exercise increased platelet P-selectin expression, CD11b expression in neutrophils and lymphocytes, and platelet and leukocyte responses to thrombin, ADP, platelet activating factor, and N-formyl-methionyl-leucyl-phenylalanine (fMLP) in vitro. Consistent with enhanced platelet and leukocyte activation, more circulating platelet-platelet and platelet-leukocyte aggregates were detected after exercise (P2, decreased P-selectin expression in single platelets at rest (PConclusions—Exercise induced platelet and leukocyte activation and platelet-leukocyte aggregation in vivo, and it increased platelet and leukocyte responsiveness to in vitro stimulation. Aspirin treatment attenuated certain signs of platelet activity in vivo at rest and fMLP-induced neutrophil activation in vitro, but it did not attenuate the prothrombotic effects of exercise.