Some observations on the release of extrinsic and intrinsic plasminogen activators during exercise in man.

Exercise was found to cause the release of 'extrinsic' plasminogen activators into the bloodstream. The 'intrinsic' plasma plasminogen activators were not significantly altered although factor VIII clotting activity and, to a lesser extent, its related antigen were both raised. A small amount of systemic fibrin(-ogen)olysis was indicated by the generation of fragment X and a slight reduction in the amount of intact A alpha-fibrinogen chain present. Plasminogen and antiplasmins were not significantly affected by exercise. We conclude that exercise-induced fibrinolysis is brought about solely by the release of plasminogen activators(s) from the vessel wall but that this enhanced level of fibrinolysis is insufficient to produce a marked degree of systemic fibrin(ogen) breakdown.