THE EFFECT OF DIFFERENT EXERCISE INTENSITIES ON THE FIBRINOLYTIC SYSTEM

The effects of moderate 30-min cycle ergometer exercise (aerobic metab olism) followed by short-term exercise at maximal capacity (anaerobic metabolism) on fibrinolytic activity were investigated in ten female a nd ten male healthy, untrained subjects. The following parameters of f ibrinolytic activity were measured initially (t0), at the end of the a erobic phase (t1), at the end of the anaerobic phase (t2) and after a 30-min recovery period (t3): tissue plasminogen activator (PA(t)) acti vity, PA(t) concentration, plasminogen activator inhibitor (PA(i)) act ivity, and D-Dimer concentration. Moderate long-term exercise caused a slight but significant increase in PA(t) concentration and PA(t) acti vity (t1; P < 0.01), whereas short-term exercise at maximal capacity ( t2) Produced a substantial elevation in both these parameters (P < 0.0 1). This would suggest that PA(t) was not inhibited totally by PA(i) w hich would itself seem to be consumed during exercise. In addition, a slight exercise intensity-dependent increase in D-Dimer concentration was measured - circumstancial evidence not only for elevated fibrinoly tic potential, but also for an actual increase in fibrin degradation ( t2: P < 0.01). After t3 both PA(t) activity and D-Dimer concentration were still slightly but significantly increased. The results obtained in the tests of fibrinolytic activity showed no significant difference between the men and the women. It would seem that the release of PA(t ) is more markedly stimulated by short-term intense physical exercise than by long-term moderate exercise and actually causes increased fibr in degradation.