Extended Data Fig. 8: Volitional adaptations of walking during otherwise unchanged spatiotemporal EES.

a–c, Quantifications of experiments shown in Fig. 4a–c for each participant. a, Step height and TA EMG activity with and without EES during overground walking (P1, EES ON: n = 7 gait cycles; P2, EES ON: n = 16 gait cycles; P3, EES ON, n = 7 gait cycles). b, Step height and TA EMG activity during normal steps and when participants were requested to perform exaggerated step elevations during overground walking (P1, n = 15 normal gait cycles, n = 11 exaggerated gait cycles; P2, n = 31 normal gait cycles, n = 23 exaggerated gait cycles; P3, n = 14 normal gait cycles, n = 10 exaggerated gait cycles). c, Step height and TA EMG activity during the first and last 30 steps extracted from a sequence of 1 h of locomotion on a treadmill (n = 30 gait cycles for all conditions). ***P < 0.001; n.s., non-significant; Student’s t-test. d, EMG activity of representative leg muscles, vertical displacements of the foot and anteroposterior oscillations of the leg (virtual limb joining the hip to the foot) while P2 was walking continuously on the treadmill with spatiotemporal EES (open loop). The participant was asked to suppress the effects of EES and stand during one cycle of open-loop spatiotemporal EES sequence, highlighted in brown (SKIP), whereas he actively contributed to the production of movement the rest of the time. Plots report the quantification of step height and TA EMG activity during walking and when skipping steps for each participant (P1, n = 13 normal gait cycles, n = 1 skipped cycles; P2, n = 36 normal gait cycles, n = 3 skipped gait cycles; P3, n = 11 normal gait cycles, n = 2 skipped cycles). e, EMG activity of two representative muscles, vertical displacements of the foot and anteroposterior oscillations of the leg while P1 was walking on the treadmill and the speed of the belt increased progressively from 0.8 to 2 km h^–1. Plots show relationships between treadmill speed and mean stride length and TA EMG activity in all participants (P1: n = 9, 9, 9, 9, 10, 18, 15, 9, 9 gait cycles for increasing speeds; P2: n = 13, 10, 7, 8, 10, 9 gait cycles for increasing speeds; P3: n = 8, 8, 10, 9, 9, 8 gait cycles for increasing speeds; s.e.m. shown). The range of tested speeds was adapted to the walking ability of each participant.