Fig 1.
Experimental setup and procedure for the step-aside movement.
Fig 2.
“Step-aside to the right” movement sequence was divided into two phases: The “left push” phase and the “right loading” phase.
According to the method by Yiou et al., each phase was further divided into three periods [20].
Fig 3.
Marking example of the start (M1) and end (M2) point for a single (a) “left push phase” and a single (b) “right loading phase”. Red circles indicate the moment for M1 and M2. CoPx: center of pressure mediolateral displacement; vGRF: vertical ground reaction force.
Fig 4.
The change in (a,b) bilateral vGRF, and (c,d) ipsilateral normalized EMG amplitudes and CoP displacement during the step-aside movement. Data on the plot represent the means from 15 subjects. SDs are not shown on EMG amplitudes for clarity purposes. Gray boxes on (c) indicate statistically significant different regions between EMG activations from SPM1d analysis. *: p < 0.05. Two vertical dotted lines divide each phase into three periods, respectively. APA: anticipatory postural adjustment.
Fig 5.
SPM results (Hotelling’s T2 test statistic trajectory) depicting the differences in muscle activities between the left push and the right loading phases.
The critical threshold (black dashed line) is 45.206. *: p < 0.001.
Fig 6.
Standardized regression coefficients (β) of EMG_Lt.PL, EMG_Lt.TA, and EMG_Lt.SOL with (a) foot CoPx displacement, (b) foot CoPy displacement, and (c) vGRF during the left push phase. The box height represents the mean value, and the circles represent individual data points. The Bayes factors (BF10) indicate the evidence level that the regression coefficients are different from zero. (d) R2 of the three dependent variables Red arrow with (*) shows the significantly different pair on ANOVA post-hoc comparison (p < 0.05 Tukey). Numbers in the box represent the mean values of the variable.
Fig 7.
Standardized regression coefficients (β) of EMG_Lt.PL, EMG_Lt.TA, and EMG_Lt.SOL with (a) foot CoPx displacement, (b) foot CoPy displacement, and (c) vGRF during the right loading phase. The box height represents the mean value, and the circles represent individual data points. The Bayes factors (BF10) indicate the evidence level that the regression coefficients are different from zero. (d) R2 of the three dependent variables Red arrow with (*) shows the significantly different pair on ANOVA post-hoc comparison (p < 0.05 Tukey). Numbers in the box represent the mean values of the variable.