Inclusion Criteria:  untrained healthy (less than 2 hours of sport per week) free from muscular, bone or joint injuries free from neurologic disease  Exclusion Criteria:  taking neuroactive substances that can alter corticospinal excitability Heart or respiratory failure. Subjects who have taken corticosteroids within 3 months (inhalation, infiltration or history of corticosteroid therapy). Pregnant woman Subject under guardianship