Movement protocols, and EMG recordings during static and dynamic contractions of middle deltoid. Static contractions. The positioning of the arm was done through abductions movements in the scapular plane. This plane is 30° of coronal plane. The structure for reference of movements allows the correct global positioning (posture) among experimental subjects. A custom made angular positioning device was attached to the frame of reference. The movable part of angular positioning device is displaced by the arm of subject. The fixed part has a gradual scale with the positions of 0° to 90° in step of 10°. The recording electrodes are placed in the middle deltoid (bipolar configuration). The reference electrode is placed in the forearm of the subject. Dynamic contractions. Dynamic contractions were evoked by abduction and adduction movements in the scapular plane. A custom made angular displacement sensor was attached to each experimental subject for monitoring of arm position.