Electromyography

Sensor technology: use active differential sensors of highquality technology. Ensure that there is no instrumentation or electrical connection introducing line interference in the recording.

EMG sensor: use sensors with small (1 cm or less), and possibly fixed, inter-electrode spacing. 

Reference electrode: ensure the reference elec-trode, if separate from the EMG sensor, is con-nected to the instrumentation and to the skin of the subject

Sampling rate: ensure that the surface EMG signal is sampled at least at 1000 Hz.

Amplifier gain: a gain of 1000 is usually appro-priate for surface EMG signals. Ensure that no clipping is present in the signal, i.e. that the signal amplitude does not exceed the maximum value allowed by the recording system (satura-tion). If this occurs, check that the EMG sensor and reference electrode are adequately attached and connected. If possible, reduce the gain or reposition the EMG sensor to reduce the signal level.

Skin preparation: remove excessive hair; clean the skin with alcohol to improve electrical contact with the sensor; if necessary peel off the dead skin (i.e. with a hypo-allergic adhesive tape).

Sensor placement: place the EMG sensor in the in the middle of the muscle belly, away from known innervation zones and tendon origins, with the electrodes aligned parallel to the muscles fibres. Position the sensor as far as possible from sources of physiological noise, ensuring that both electrodes are equidistant from the source in single differential sensors.