 EMG EMG will be recorded with a MyoSystem 1400L using surface electrodes. The skin will be shaved if necessary and the electrodes will be attached with double sided tape and plaster. The electrodes will be placed at the level of the lateral gastrocnemius, medial gastrocnemius, tibialis anterior and peroneus longus, and on the thigh at the level of the vastus lateralis, vastus medialis and lateral hamstrings and medial hamstrings. There will be 2 electrodes per muscle fixed one against the other and one reference electrode placed at the level of the C7 vertebra. 