Fibrinolytic response to exercise in women using third-generation oral contraceptives

The use of oral contraceptives (OC) is associated with an increased risk of thrombosis, suggesting OC exert procoagulant and/or antifibrinolytic effects. Given that physical exercise physiologically leads to an activation of blood coagulation and fibrinolysis, this study tested the hypothesis that OC might compromise the fibrinolytic response to exercise. Fibrinolytic variables were measured in 10 women (24 2 years) using OC (a formulation containing 30 mu g ethinylestradiol and 150 jig desogestrel) and in 11 women without OC (mean +/- SD, 27 +/- 3 years) before, during and after a 1-h run on a treadmill at a velocity corresponding to an oxygen demand of 75-80% of maximum (anaerobic threshold). Exercise testing gave rise to considerable increases of tissue-type plasminogen activator antigen by seven-fold to eight-fold in women taking and not taking OC alike. In the presence of unchanged plasma levels of plasminogen activator inhibitor-1, exercise-induced release of tissue-type plasminogen activator led to enhanced plasmin formation with respect to plasmin-antiplasmin complexes, rising by (mean standard error) 701 +/- 77 ng/ml (P < 0.001) in women using OC and by 695 +/- 117 ng/ml (P < 0.001 versus baseline; NS versus OC users) in controls. The fibrinolytic response to intensive physical exercise is preserved in women using OC and is similar to women not using OC.