Hemostatic responses to maximal exercise in oral contraceptive users

OBJECTIVE: This study examined the effect of exercise on markers of fibrino lysis and coagulation in users and nonusers of oral contraceptives. STUDY DESIGN: Fourteen oral contraceptive users and 14 nonusers performed a maximal exercise test on a cycle ergometer. Blood samples were collected b efore and immediately after the completion of the test. A repeated-measures analysis of variance was used for statistical analysis with values conside red significant at P = .05. RESULTS: Acute maximal exercise resulted in significant increases in tissue plasminogen activator activity in both groups. There was a trend toward a smaller increase in tissue plasminogen activator activity in oral contracep tive users, but the difference between groups was not statistically signifi cant. Plasminogen activator inhibitor 1 activity was reduced with exercise in both groups but with a significantly greater decrease observed in the no nusers (P < .0001). Prothrombin fragment 1+2 was significantly higher (P < .0001) in the oral contraceptive group but did not change with exercise. Ep inephrine levels before and after exercise were similar between the 2 group s, but postexercise norepinephrine concentrations were significantly lower (P = .026) in the oral contraceptive users. CONCLUSION: These data suggest that oral contraceptive use blunts the fibri nolytic response to exercise. This, together with increased coagulation act ivation in oral contraceptive users, may alter the hemostatic balance durin g exercise.