Turnover of fibrinogen, plasminogen, and prothrombin during exercise in man.

The turnover of biologically intact high-purity 125I- and 131I-labeled fibrinogen, plasminogen, and/or prothrombin was studied in 16 untrained healthy subjects before and during strenuous physical exercise on a bicycle ergometer (repeated 4 times/day for 2 days). The exertion resulted in the well-known changes in the coagulation and fibrinolytic tests but did not induce changes in the concentration of fibrinogen, plasminogen, or prothrombin in the plasma. A significantly increased catabolism of fibrinogen and plasminogen but not of prothrombin was observed. The extent of Aalpha-chain degradation of fibrinogen in the plasma was quantitated before and 2 h after exercise, and a significant increase in degraded Aalpha chains was found in the postexercise samples. Immunochemical estimation of plasmin-antiplasmin complex in four subjects revealed a small increase after exercise in three of them. All these data support the concept that plasminogen activation and plasmin-induced fibrinogen degradation occur to some extent in man following strenuous physical exercise.