Applications of twitch interpolation technique in assessment of muscle activation

The twitch interpolation refers to a technique that applies a brief electrical stimulation to a muscle or the nerve trunk that innervates the muscle during a maximal voluntary contraction, and uses the difference in the forces produced by the stimulation-evoked and the voluntary contractions to evaluate the capacity of the central nervous system in activating skeletal muscles. This technique has been frequently used to evaluate muscle activation, assess the effects of strength training programs, and determine the sites and mechanisms of fatigue during motor activities. The purpose of this review is to provide an overview of the principles, applications and commonly encountered problems in using this method.