5. 20 healthy controls Objective: asses the muscular oxygenation modifications during a standardized effort and compare the variables between groups. Analyze the mitochondrial function and phenotype in the BMD group compared to healthy controls Outcome : Muscle Oxygenation by Near Infrared Spectroscopy parameters; oxygen consumption, Muscle Function Measure, Vignos and Brooke score, Borg scale, 6 minutes walk test, mitochondrial phenotype, mitochondrial oxygenation 3 visits : 1- inclusion 2- standardized effort protocol 3- for Becker dystrophy patients and voluntary controls, muscle biopsy of the Vastus Lateralis