Rudroff, T., Bojsen-Moller, J., Poston, B., & Enoka, R. M. (2006). Transient recruitment of motor units is altered in weightlifters during sustained submaximal contractions. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 2406.

This study attempted to identify those factors that could explain the time to failure for a submaximal isometric contraction performed by weightlifters. Males (N = 5) maintained a constant elbow-joint angle with a contraction sustained at 20% maximum voluntary contraction force for as long as possible. The elbow was flexed to 1.57 rad with the forearm vertical and supinated. Bursts of activity in the EMG signal were used as an index of the transient recruitment of motor units. Performance characteristics were compared to those of non-trained individuals.

Ss who exhibited a greater frequency of transient recruitment of motor units in the short and long heads of the biceps brachii were able to maintain the arm position while supporting the inertial load for a longer time.

Implication. The ability to withstand fatigue is dependent upon the trained state of the action in question. Without specific training, an action is no more than an untrained activity. It would not be likely to exhibit exceptional performances. The degree of specific training will govern the quality and duration of an exercise performance.

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