BACKGROUND: In a previous smaller study, we found evidence of a diminished global coagulation capacity after maximal exercise in patients with severe haemophilia A (HA).

AIM: To validate these results, we repeated the study in a larger cohort. We also examined if the exercise-induced increased levels of von Willebrand factor (VWF) might prolong the effect of factor concentrate administered just before exercise.

METHODS: We studied individual and global coagulation parameters after maximal physical exercise in 10 persons with severe HA and 10 healthy matched control subjects. Blood samples were taken before, 10 minutes, 60 minutes and 4 hours after exercise.

RESULTS: Rotational thromboelastometry (ROTEM) and thrombin generation assay-calibrated automated thrombogram (TGA-CAT) showed significantly increased coagulation capacity after maximal exercise in healthy controls but not in patients with severe HA. VWF antigen and activity levels increased significantly in both groups, whereas FVIII:C only showed a significant increase in the control group. No statistically significant differences were seen between FVIII pharmacokinetic results obtained with and without exercise.

CONCLUSION: Our findings do not support the presence of a FVIII-independent mechanism that increases global coagulation, but rather underscores the importance of FVIII in mediating the increased coagulation capacity seen after exercise. Our results could not support the hypothesis that exercise-induced increased levels of VWF for patients with severe HA lead to a prolonged effect of factor concentrate administered just before exercise.