Exercise Capacity of Patients with Dermatomyosis

Inclusion Criteria:

• Woman or man> 18 years,

• Signature of informed consent,

• Muscle biopsy for suspicion of recent inflammatory myopathy (<6 months) or forexclusion of neuromuscular pathology.

Prospectively, following the results of the muscle biopsy, the subjects will divided into three groups meeting the following criteria:

• "DM" group: DM according to the ENMC criteria;

• "other inflammatory myopathy" group: polymyositis, autoimmune necrotizing myopathy,non-specific myositis or inclusion myositis according to the ENMC criteria;

• Group "no neuromuscular pathology": i) myalgia and / or intolerance to exercise andii) normal neuromuscular examination, iii) no increase in blood creatine kinaselevel, iv) absence of electromyographic abnormality, v) histological Muscle mass.

Exclusion Criteria:

• Taking an immunomodulatory treatment within 6 months before inclusion,

• Paraneoplastic form of the disease,

• Presence of associated interstitial pneumonitis,

• Neuromuscular pathology different from inflammatory myopathy,

• Unbalanced cardiovascular disease,

• Impossibility of giving the subject informed information (subject in an emergencysituation, difficulty in understanding the subject, ...),

• Subject under safeguard of justice,

• Subject under tutelage or under curators,

• Pregnancy (positive pregnancy test)

• Breastfeeding.