Fig. 3

a Normalized activation coefficient curves of the four extracted kinematic synergies, and their (b) FWHM and CoA values for the four groups. Each thick solid line denotes the median of activation coefficient curves corresponding to the kinematic synergy in each group. Vertical dotted lines separate the swing and stance phases during a crawling cycle. For FWHM, black *LU-dominant synergy > RU-dominant synergy > LL-dominant synergy > RL-dominant synergy; otherwise, red *(paired t test or Wilcoxon signed-rank test). The meanings of black/red *for CoA are opposite to those for FWHM. Black #TD > ARDD > AHRDD > CDD; otherwise, red # [Kruskal–Wallis test (Tukey post hoc)]. */#p < 0.05, **/##p < 0.01, ***/###p < 0.001