Electromyographic

Electromyography (EMG) is the study of the electrical activity produced by skeletal muscles. The term electromyographic describes methods that record, analyze, or interpret such activity. EMG is used to assess the health of muscles and the nerve cells that control them (motor neurons). It complements nerve conduction studies in evaluating neuromuscular function.

Two main approaches are employed: intramuscular (needle) EMG and surface electromyography (sEMG). Needle EMG uses fine electrodes inserted into a specific muscle to record the electrical potentials of individual motor units. Surface EMG uses skin-mounted electrodes to measure the summed electrical activity of a muscle, with lower invasiveness but greater susceptibility to cross-talk and skin impedance.

EMG data are recorded with amplifiers and filters and interpreted through features such as motor unit action potentials, firing rates, and recruitment patterns. Clinically, EMG helps diagnose neuropathies, radiculopathies, myopathies, and motor neuron diseases, and it can guide treatment decisions or rehabilitation planning. It is commonly performed together with nerve conduction studies.

Limitations include discomfort with needle techniques, potential risk of infection, and non-specific findings that require expert interpretation. Surface EMG is prone to cross-talk from adjacent muscles and may be affected by skin conditions and adipose tissue. EMG data also support research in biomechanics, ergonomics, sports science, and the study of motor control.