PMC

A, as described in Methods, the three groups of control mice underwent (i) neither training nor walking, (ii) a 6 h period of walking but no prior training, or (iii) training but not the 6 h period of walking. The fourth group underwent both training and 6 h walking. The values shown for HDC activity were obtained from quadriceps femoris muscles removed immediately after the final period of walking. Each value represents the mean ±s.d. from 5 mice. *P < 0.01. B, as described in Methods, the 3 groups of control mice underwent (i) neither starvation nor walking, (ii) a 6 h period of walking but no prior starvation, or (iii) starvation but not the 6 h period of walking. The fourth group underwent both starvation and 6 h walking. The values shown for HDC activity were obtained from quadriceps femoris muscles removed immediately after the period of walking (or starvation if they were not to perform walking). Each value represents the mean ±s.d. from 5 mice. *P < 0.01.

Deep colors (black, blue, and red) and thin colors (grey, light blue, and pink) are normoxia and hypoxia, respectively. Solid and dotted bars are walking and running, respectively. WN, RN, WH, and RH mean walking at normoxia, running at normoxia, walking at hypoxia, and running at hypoxia, respectively. * walking > running within normoxia or hypoxia, § walking < running within normoxia or hypoxia, and † normoxia > hypoxia within walking or running, respectively. Data are mean ± S.D.

Relationships between anterior ground reaction force (AGRF) and walking speed (N=38). (A–D): Pre-training. (E–H): Post-training. “SS” denotes self-selected walking speed and “FS” denotes faster walking speed. “BW” denotes the bodyweight. “†” indicates p < 0.01. (A) Relationship between paretic propulsive force and self-selected walking speed at pre-training. (B) Relationship between non-paretic propulsive force and self-selected walking speed at pre-training. (C) Relationship between paretic propulsive force and faster walking speed at pre-training. (D) Relationship between non-paretic propulsive force and faster walking speed at pre-training. (E) Relationship between paretic propulsive force and self-selected walking speed at post-training. (F) Relationship between non-paretic propulsive force and self-selected walking speed at post-training. (G) Relationship between paretic propulsive force and faster walking speed at post-training. (H) Relationship between non-paretic propulsive force and faster walking speed at post-training.

Robustness of muscle synergies across unperturbed walking conditions. A, Muscle synergies extracted from different walking speeds were similar. Shown are example muscle synergies from one subject extracted from slow walking trials and self-selected speed walking trials combined, slow walking catch trials, and self-selected speed walking catch trials. Correlations between each muscle synergy vector and the corresponding muscle synergy from combined self-selected and slow walking data are shown. B, Muscle synergies extracted from unperturbed self-selected speed walking with and without anticipation have similar muscle synergy composition. Shown are muscle synergies extracted from walking catch trials (with anticipation) and walking control trials (no anticipation). Correlations between muscle synergy vectors are shown.