Physical activity is lower in patients with haemophilia than in their healthy peers. Nevertheless, exercize is recommended for those patients and supported by evidence. Until 2013, scientific and medical evidence to encourage physical activity for patients with haemophilia were listed to increase their locomotor function, their metabolic status, their fitness level and their well-being. In 2013, an original publication by Groen et al. suggested that physical activity could also interact with the specific and biological disturbance of the disease.

We propose to consider that regular endurance exercize prescription should be encouraged in patients with haemophilia not only for a healthier lifestyle but also because it could positively alter the specific biological blood disturbance seen in haemophilia. Nevertheless, before planning a well powered intervention trial we need to determine the acceptability of regular exercize and the expected value of factor Factor VIII, von Willebrand factor and von Willebrand propeptide after an endurance training program.

Inclusion Criteria:

• Mild (FVIII:1-5%) and moderate (FVIII:6-40%) haemophilia A patients,
• Living in the Midi-Pyrenees region,
• Between 18 and 45 years old,
• Exempt from any significant medical condition that could prevent them from being subjected to an endurance training program,
• Affiliated to a social security cover

Exclusion Criteria:

• Women
• Subjects declaring 2 or more spontaneous bleeding events and/or 4 or more induced bleeding events out of a traumatic circumstance 6 months prior to inclusion
• Absence of signed consent
• Patient protected by Justice