Research Question: Does an specific and pre-defined physical exercise prescribed by a specialist provide any benefit on haemophilic arthropathy, the quality of life or the physical condition of patients with haemophilia A and haemophilic arthropathy? Does adherence to physical exercise improve when monitoring patients with an accelerometer? Do compliant patients find higher benefit on haemophilic arthropathy, quality of life or the physical condition than non-compliant patients?

Primary Endpoint: Assess in patients with haemophilia A and haemophilic arthropathy if a prescribed and specific physical exercise monitored by an accelerometer is producing any change in the following domains: progress of haemophilic arthropathy; health-related quality of life; physical condition.

Secondary Endpoints: Evaluate the adherence to physical exercise in patients with haemophilia A and haemophilic arthropathy by means of accelerometry, and asses if compliant patients achieve higher improvement in these 3 domains than non-complaint patients.

Specific details of Treatment/Intervention:

Physical exercises that are part of the specific medical program prescribed for each patient. The exercise program for each patient will depend of the haemophilic arthropathy, the level of physical condition and the preferences of the patient.

Monitoring of physical activity will be made by means of accelerometers. Its use does not alter the daily activities and does not require any change of the patients' individual habits. The assessment of the patients' cardiovascular condition will be made using pulse monitors. Normal examinations in clinical practice will be revised as well as those specific to each patient reference health centre, muscle strength and joint use testing which will be validated with force measurement devices. Assess by means of an ultrasound system the baseline situation of the joints used for daily activities for injury control. Determine the likelihood of fracture and assess the bone quality by means of densitometry. Thermal cameras will allow to analyse the characteristics of Joint inflammation. It may be suitable for bleeding evolution control. Measurements given by densitometers will allows to determine the state of bones of the participants in the study (osteoporosis measurement). Number of bleeding events/hemarthrosis during the period of study. Determine the activity of hemarthros/synovitis using thermal images.

Inclusion Criteria:

• Male patients over 18
• Patients diagnosed with haemophilia A and under prophylaxis treatment with the same FVIII for 2 years prior to the inclusion in the study.
• Patients with haemophilic arthropathy in, at least, one of the four load-bearing joints (knees and ankles), according to clinical and/or radiographic criteria (at least 3 in the Gilbert scale and /or at least 3 in the Pettersson scale) and/or Chronic synovitis evidenced by ultrasound.
• Patients with signed informed consent.

Exclusion Criteria:

• Patients who have developed an inhibitor antibody (≥5 Bethesda units), at the moment of the inclusion in the study.
• Development of inhibitors
• Modification, during follow-up, of FVIII with which the patient started the study.
• The patient decides to withdraw voluntarily from the study.
• Major orthopaedic surgery

Adult patients with haemophilia A presenting joint disease (haemophilic arthropathy) and who are under prophylaxis treatment with FVIII