F-Wave Latency

The F-wave is a long latency muscle action potential seen after supramaximal stimulation to a nerve. Although elicitable in a variety of muscles, it is best obtained in the small foot and hand muscles. It is generally accepted that the F-wave is elicited when the stimulus travels antidromically along the motor fibers and reaches the anterior horn cell at a critical time to depolarize it. The response is then fired down along the axon and causes a minimal contraction of the muscle.

Essentially, F-Wave latency is a measure of how long it takes for a signal to travel the full length of a nerve. This parameter is commonly measured during nerve conduction studies that are performed on CMTers.