Endurance training modifies exercise-induced activation of blood coagulation: RCT.

Randomized controlled trials (RCTs) on the topic of physical training and blood coagulation are rare and the effects are unclear. The aim of this study was to investigate whether endurance training adjusts blood coagulation and fibrinolysis at rest and after exercise. The study included 50 healthy untrained non-smokers randomized into training (TR 49 ± 6 years) or control group (CO 48 ± 6 years). Each subject performed an exercise test adjusted at 80 % individual anaerobic threshold (IAT) for 60 min before and after 12 weeks (80 % IAT: before TR 123 ± 20, CO 125 ± 26 W; after TR 148 ± 23 W, CO 127 ± 25 W; mean ± SD). Blood was taken at rest and after exercise to determine coagulation (e.g., aPTT, thrombin potential, TAT, F1+2, several coagulation factors) and fibrinolytic (e.g., tPA, PAI) parameters. The training intervention induced an elevation of physical capacity in TR by 17 % (rel. VO2max) that led to a statistical relevant prolongation of aPTT at rest. Although absolute power output during the second exercise test was 20 % higher in TR, we detected an attenuated exercise-induced decrease of aPTT and attenuated increase of F1+2 after training. Resting levels of tPA- and PAI-Ag decreased slightly but not significantly after training. Exercise-induced changes were comparable after training in spite of higher power output in TR. Although the effects are small in healthy men, training modifies exercise-induced blood coagulation positively. The fact that exercise-induced changes in blood coagulation and fibrinolysis are rather attenuated or unchanged in the training group, in spite of a 20 % higher absolute power output during exercise, substantiates the adjusting effect of endurance training and the importance of physical fitness in primary prevention.