Surface EMG Recording of Forearm Muscles

Surface EMG were recorded using six pairs of electrodes (Ambu® Neuroline 720 01-K/12, Ambu A/S, Denmark) mounted on the dominant forearm. The electrode pairs were equally spaced around the forearm, one third distal from the elbow joint, similar to previous studies [11 (link),12 (link)]. An example of the placement of the electrodes are shown in Figure 3a and b. The signals were recorded in monopolar derivation, with the reference electrode on the olecranon, amplified with a gain of 2000, filtered between 10 and 900 Hz, and sampled at 2048 Hz (EMG-USB2, OT Bioelettronica, Italy). All experiments were performed with the arm in neutral position (at the side of the body) and with the elbow close to full extension. The data were processed in real time, and online feedback was provided to the subject. The data processing period was 100 ms.