Abstract:
The objective of the present study was to investigate the strength of the three heads of triceps brachii muscle during handgrip force exercise with full elbow extension through surface electromyography. The myoelectric signals were recorded from the lateral, long and medial heads of triceps brachii muscle of 11 healthy men during maximal isometric contractions for 10-s of concurrent handgrip force and elbow extension. The subjects were asked to perform their contraction task five times with 3-min interval between the two successive contractions. Among the three heads of triceps brachii muscle, the higher normalize root mean square amplitude were found at the first 5-s duration (FD) compare to the last 5-s duration (LD). The normalized root mean square amplitude changes were obtained between FD and LD in lateral head (7.995%), long heads (5.435%), and medial head (1.144%). The electromyographic activities between the period of FD and LD were not statistically significant within the head for lateral (p = 0.178), long (p = 0.491), and medial (p = 0.448). These findings supported that the triceps brachii muscle strength is decreased by the increasing of contraction duration of the muscle fiber, where the muscle strength of the medial head might be more stable and followed the long and lateral head.
