Bioelectric characteristics of the electromechanical delay preceding concentric contraction.

Fifteen male subjects performed a series of unrestricted, unidirectional 45 degrees elbow extensions at three different initial muscle lengths and at four movement velocities. Online electromyography, accelerometry, and electrogoniometry were used in the data collection to investigate the relationship between the myoelectric activity during the electromechanical delay and various kinematic variables representing the concentric phase of the muscular contraction. Results indicate that the integral of the myoelectric signal during the electromechanical delay is a more reliable variable than the duration of the latency which was shown to be inconsistent in its ability to discriminate between manipulated conditions. It appears that the use of electromyographical quantification of the electromechanical delay can be useful in the derivation of preacceleration muscular force and perhaps provide an noninvasive technique to quantify the elastic characteristics of muscle and the contributions of the elastic response to movement.