Fatigue and Skeletal Muscle Impact in Severe Axial Spondyloarthritis

"The incremental effects tests will be performed in a service specialized in the exploration of the exercise (physiology or cardiology according to the centers) in a spacious and air-conditioned room, in the presence of a medical specialist. exercise and close to the resuscitation equipment.~Before the test, weight and height will be collected. Information on the conduct of the test will be given to the patient. A multi-derivation ECG recording will be detected throughout the duration of the test and followed by a physician experienced in the ECG effort.~O2 saturation by oximetry of hens will be recorded continuously. Blood pressure will be recorded at each level. The collection of expired gases in the face mask whose tightness will be verified to measure the fractions inspired and expired in O2 and CO2 (Sensor Medics Vmax229, Yorba Linda, CA, USA) and calculations VO2 max and VCO2.~Maximal power (W max) will be recorded. Patients will be encouraged during the test."