 Video Movements of the subject will be recorded by means of a high-speed digital camera Basler. In order to facilitate video analysis, 7 reflective markers hemisphere with a 12 mm diameter will delimit body segments: 3 will be glued on one shoe, 3 will be fixed on the skin with the same method used for EMG electrodes at the level of the ankle, knee, hip of one limb and the last one will be fixed on the neck. 