Blood coagulation and fibrinolysis in healthy, untrained subjects: effects of different exercise intensities controlled by individual anaerobic threshold

The influence of different exercise intensities on haemostasis in healthy, untrained subjects has not been intensively studied. We investigated untrained subjects for alterations in coagulation and fibrinolysis induced by two exercise intensities, precisely controlled by individual anaerobic threshold (IAT). Twenty-five healthy, untrained non-smokers (age 25 ± 3 years; relative VO₂ peak 43.1 ± 5.2 ml/kg/min) underwent exercise tests at 80% (moderate) and 100% (strenuous) of IAT for 60 min. Blood samples were taken after 30 min rest and immediately after exercise. The present results reveal that an exercise intensity at 100% IAT induces a more pronounced coagulation activity than exercises at 80% IAT. 100% IAT led to a significant higher increase in FVIII (80% IAT 85 ± 33 to 114 ± 30% vs. 100% IAT 81 ± 20 to 132 ± 29%) and TAT (80% IAT 2.5 ± 1.4 to 2.9 ± 1.0 μg/l vs. 100% IAT 2.6 ± 1.0 to 5.4 ± 4.2 μg/l). Furthermore, both exercises affected fibrinolysis, but it was significantly higher at 100% IAT (tPA activity; 80% IAT 0.44 ± 0.17 to 4.65 ± 2.67 U/ml vs. 100% IAT 0.43 ± 0.19 to 6.47 ± 3.97 U/ml). The data show that fibrinolytic activity is significantly elevated already after moderate exercise (80% IAT). After strenuous exercise (100% IAT), coagulation is more sharply enhanced together with a higher increase of fibrinolysis in comparison with 80% IAT. However, haemostasis seems to be in balance after moderate as well as after strenuous exercise intensity in healthy, untrained participants. Based on these data, exercise-induced changes of both haemostatic systems should also be tested in patients with cardiovascular diseases in order to be in a position to give recommendations for endurance training modalities in rehabilitation training.