Comparison of the effect of muscle fatigue resulting from submaximal and maximal muscle contractions on changes in muscle synergy and height control: According to impulse interpolation technique

The aim of this study was to compare the effects of maximal and submaximal fatiguing contractions on voluntary postural stability and muscle synergies.

Following isometric maximum voluntary contraction (IMVC) tests, 12 volunteers randomly performed submaximal and maximal fatiguing contractions of the plantar flexors. Before and after the fatiguing protocols, the central fatigue, peripheral fatigue, the centre of pressure and activities of 12 muscles was recorded. Repeated measure ANOVA dependent T was used for data analysis.

Rest twitch size was smaller after maximal than submaximal fatiguing contractions. Voluntary activation and IMVC decreased significantly more after submaximal than maximal fatiguing contractions. M wave was not changed significantly after two protocols of fatiguing contractions. Furthermore, in comparison with the maximal fatiguing contractions, the submaximal fatiguing contractions lead significant decrease in variance of muscles activity and muscle synergies. The ellipse of COP area also increases significantly after submaximal than maximal fatiguing contractions (p < 0.05).

The outcome of this study suggests that training programs for patients with balance and muscle synergies issues should be based on training with submaximal rather than maximal load.