electromyografia

Electromyography is the technique used to record the electrical activity produced by skeletal muscles. It provides information about muscle function and the integrity of the motor units and neuromuscular system. EMG is used in clinical diagnosis, research, and rehabilitation, as well as in ergonomics and sports science.

There are two main approaches. Surface electromyography (sEMG) uses non-invasive electrodes placed on the skin over a muscle to measure aggregated electrical activity. Intramuscular electromyography uses needle electrodes inserted into the muscle to record motor unit action potentials and single-fiber activity. Signals reflect the recruitment and firing of motor units and can be analyzed in time and frequency domains to assess muscle health and function.

Typical EMG procedures involve skin preparation and careful electrode placement. Needle EMG can be uncomfortable but is generally well tolerated; it provides detailed information about individual motor units. EMG is often performed together with nerve conduction studies to distinguish between nerve and muscle disease. Safety considerations include a small risk of discomfort, infection, or bleeding, and contraindications related to skin infection or bleeding disorders.

Applications span neuromuscular disorders such as amyotrophic lateral sclerosis, radiculopathies, polyneuropathies, and muscular dystrophies, as well as assessment of muscle strength, coordination, and fatigue. In research and clinical practice, EMG aids in understanding motor control, rehabilitation planning, prosthetics control, and ergonomic assessment. Limitations include operator dependency, signal cross-talk in surface recordings, and variability in electrode placement and skin impedance, all of which require standardized protocols and expert interpretation.