Recommended surface EMG electrode position for wrist extension and flexion

To obtain a high-quality surface electromyography (EMG) recording, the signal must be acquired as far as possible from the muscle innervation and tendon zone. This study presents a technique to indicate better electrode positions for surface EMG of the upper limb muscles during wrist extension and flexion. Ten volunteers participated in this research. Surface EMG signals were collected from flexor carpi radialis and extensor carpi radialis muscles. Three different electrode positions with 2 cm internal distance between the bipolar electrodes were investigated. The duration of muscle contraction was selected using the mean absolute value method for quantification, and the qualitative signal was observed through visual inspection. The power spectral density and signal-to-noise ratio were applied to compare and select the most feasible electrode position. The optimal signal from the flexor carpi radialis muscles was presented at 90%. The optimal position for the extensor carpi radialis muscles was shown at 90% of the electrode position over the forearm length. The presented method should be observed as an important step in every surface EMG application and research to ensure high quality of the signal.