Fig 1.
(a) A schematic of the experimental setup and definitions of the ankle angle θa, hip angle θh, and hip height hh. Sequence 1 consists of 8 perturbations of a large magnitude followed by one perturbation of a medium magnitude. Sequence 2 consists of 8 perturbations of a small magnitude followed by one perturbation of a medium magnitude. (b) Experimental data obtained from a representative participant for Trial 2 in Sequence 1: displacement of the force plate, hip and ankle angles, COP, and EMG signals from the left leg. The dashed line indicates the time at the onset of the perturbation. All data are aligned to the dashed line.
Fig 2.
Mean by sequence of the magnitudes of Excursion I and Excursion II of COP for Trials 1-9 (Error bars are ± 1 standard deviation of the mean).
The inlets display the definitions of COP Excursion I and Excursion II.
Fig 3.
Mean by sequence of CCIs within each period: Period 1 (± 50 ms from the onset of perturbations), Period 2 (between 50 ms and 150 ms from the onset of perturbations) and Period 3 (between 150 ms and 250 ms from the onset of perturbations) for Trials 1-9 (Error bars are ± 1 standard deviation of the mean).
Fig 4.
Mean by sequence of the ratios of the MAV (mean absolute value) of each trial to that of the first trial for Trials 1-9 (Error bars are ± 1 standard deviation of the mean).
Fig 5.
Mean by sequence of the magnitudes of Excursion I and Excursion II of (a) ankle angle, (b) hip angle and (c) COG for Trials 1-9 (Error bars are ± 1 standard deviation of the mean).
The inlets show the definitions of Excursion I and Excursion II.
Fig 6.
Means (bold) and ± 1 standard deviations (translucent) of COP traces for 1 second after the onset of each perturbation across Trial 8 and Trial 9.
Blue: Sequence 1, Red: Sequence 2.
Fig 7.
A comparison in the mean of CCI between Sequence 1 and Sequence 2 across Trials 8 and 9 for Period 3.
There is no significant main effect of trial (ANOVA, p >0.5), while a significant main effect of sequence is exhibited (ANOVA, p = 0.045). Error bars are ± 1 standard deviation of the mean. The asterisk indicates a significant main effect of sequence.
Fig 8.
Means (bold) and ± 1 standard deviations (translucent) of traces of ankle angle, hip angle and COG for 1 second after the onset of each perturbation across Trial 8 and Trial 9.
Blue: Sequence 1, Red: Sequence 2.