It is possible to record the action of skeletal muscle in the body using either strain gage sensors monitoring the displacements and forces produced by the muscle or biopotential electrodes sensing electrical activation. Direct force measurements require intimate contact between the muscle and strain gage.

For body surface recordings, this presents a problem. However, the electrical activity of skeletal muscles can be recorded by applying electrodes to the skin above the muscle in question. The pattern produced by the combined action potentials of many motor units is called an electromyogram. In this chapter we will restrict out discussion to biopotential surface recordings of this type