Surface Electromyography (sEMG)

Surface electromyography, or sEMG, is a non-invasive method for recording electrical signals from skeletal muscles using electrodes on the skin. The signals arise from electrical activity in muscle-fiber membranes. With appropriate recording and analysis, they provide information about when a sampled muscle region is electrically excited and how that excitation changes during a task .¹

Electrical excitation precedes the processes that produce muscle force. Consequently, the size of an sEMG signal is not a direct measurement of force or strength. A larger signal also cannot, by itself, show that an exercise will produce greater muscle growth or greater strength gains .¹

Interpretation depends on how the measurement is made. Electrode position, tissue between muscle and skin, muscle length, movement speed, and signals from nearby muscles can affect the recording. Electrodes sample a region rather than necessarily representing the whole muscle. Comparisons are therefore most informative when recording conditions and the movement being tested are carefully controlled .¹