The study, “Effect of moderate intensity exercise on haemostatic capacity in adults with haemophilia A and B: pilot study,” found that moderate intensity exercise induces changes promoting blood clot formation both in men with hemophilia A (HA) and hemophilia B (HB), but that these changes are sustained one hour following exercise only in men with HB.
“This raises the possibility of a difference in the hemostatic response to exercise in adult men with HA compared to HB,” wrote Dr. Michelle Sholzberg and co-authors of the study at the University of Toronto.
The researchers speculate that such a difference could be responsible for the milder phenotype seen in HB, since these patients may derive more hemostatic benefit from exercise than those with HA.
For the study, the team recruited 22 men ages 19-65 with hemophilia, 13 of which had HA and nine who had HB. They asked the men to complete an exercise protocol on a stationary cycle. They took blood from the participants before the start of the exercise as well as five minutes and one hour after exercise.
Researchers performed a complete blood count and looked at the concentration of blood clotting factors including factor VIII (FVIII) and the Von Willebrand factor (VWF).
The results showed that platelet count, FVIII, VWF, and the ratio of red blood cells over the total volume of blood significantly increased five minutes following exercise in all participants. The absolute increase in FVIII was 3% in men with hemophilia A and 66% in men with hemophilia B, representing a more clinically meaningful increase.
All factors decreased again one hour after exercise in all participants, indicating that the exercise-induced changes are reversible. However, in men with HB, even though levels of FVIII and VWF significantly decreased one hour after exercise, unlike in men with HA, they remained significantly higher compared to before the start of the exercise.
The results obtained from men with HA were in line with previous studies. However, this is the first time researchers have shown that the increase in two blood clotting factors, FVIII and VWF, induced by exercise was sustained in men with hemophilia B in contrast to men with hemophilia A.
The authors suggest that this sustained increase may be protective in HB patients and conclude that people with hemophilia B may benefit from 15 minutes of moderate intensity exercise before engaging in potentially injury-provoking sports such as soccer and basketball to raise their FVIII and VWF levels and their platelet count to minimize the risk of bleeding.