Evaluation of training effectiveness for improving maximal voluntary contraction without noticeable hypertrophy of muscles

The goal of this study was to approbate a strength training protocol designed to improve motor skills at the maximum voluntary contraction (MVC) without hypertrophy of muscles. The main difference between this protocol and classical strength training was that the number of movements during a training session was increased to improve the motor skill, and the rest periods between the training movements were increased in order to minimize the damage of muscle fibers, which is one of the factors inducing muscle hypertrophy. Eleven subjects trained knee extensors of the right leg four times a week during four weeks. The evaluation of strength and speed characteristics with simultaneous recording the EMG activity was performed in both trained and untrained legs immediately before, during, and several times after the whole training period. Before and after the four-week training period, the size and contractile properties of the trained and contralateral knee extensors were evaluated by MRI and twitch interpolation technique. The maximal strength gains were about 17% in both trained and untrained legs; they did not differ significantly from each other. Noticeable increases in the EMG activity during the training period were observed. These changes were not accompanied by any significant changes in the muscle size, which demonstrates the “neural” nature of the training effects.