Fig. 3

Experimental setup. a Position of the subject during exercise. A chair was adapted so that the elbow joint was flexed at an angle of 90°, and to secure the elbow so that the only possible movement of the arm was isometric elbow flexion. The load cell was attached to an adjustable cable, and placed next to the chair. b Placement of the 7-channel electrode array, on the ideal region of acquisition of the biceps brachii short head, after innervation zone identification