Descending neural drive reorganization to agonist-antagonist muscles is important for patients with paretic ankle muscle weakness.

The motor modules during human walking are identified using non-negative matrix factorization (NNMF) from surface electromyography (EMG) signals. The extraction of motor modules in healthy participants is affected by the change in pre-processing of EMG signals, such as low-pass filters (LPFs); however, the effect of different pre-processing methods, such as the number of necessary gait cycles (GCs) in post-stroke patients with varying steps, remains unknown. We aimed to specify that the number of GCs influenced the motor modules extracted in the consideration of LPFs in post-stroke patients. In total, 10 chronic post-stroke patients walked at a self-selected speed on an overground walkway, while EMG signals were recorded from the eight muscles of paretic lower limb. To verify the number of GCs, five GC conditions were set, namely, 25 (reference condition), 20, 15, 10, and 5 gate cycles with three LPFs (4, 10, and 15 Hz). First, the number of modules, variability accounted for (VAF), and muscle weightings extracted by the NNMF algorithm were compared between the conditions. Next, a modified NNMF algorithm, in which the activation timing profiles among different GCs were unified, was performed to compare the muscle weightings more robustly between GCs. The number of motor modules was not significantly different, regardless of the GCs. The difference in VAF and muscle weightings in the different GCs decreased with the LPF of 4 Hz. Muscle weightings in 15 GCs or less were significantly different from those in 25 GCs using the modified NNMF. Therefore, we concluded that the variability extracted motor modules by different GCs was suppressed with lower LPFs; however, 20 GCs were needed for more representative extraction of motor modules during walking in post-stroke patients.

Aim To clarify the difference in the longitudinal effects of physical exercise on health‐related outcomes according to the baseline frailty status (frail or non‐frail) in community‐dwelling older adults. Methods Participants included 177 adults aged ≥65 years who carried out multicomponent physical exercises (strength, aerobic, gait and balance) for 40 min, one to three times per week, for 1 year at a day‐care center. Bodyweight, comfortable walking speed, 6‐min walking distance and Mini‐Mental State Examination were measured at baseline and every 3 months. For longitudinal trend, we analyzed the change in scores from baseline for each outcome using the linear mixed effects model. Fixed effects included “group” (frail or non‐frail), “time” (4 time points every 3 months, from 3 to 12 months) and “interaction between group and time.” Results The effect sizes from baseline showed almost all positive values for each outcome. The linear mixed effects model showed significant effects on “interaction between group and time” in changes in bodyweight (P = 0.033), “group” in changes in walking speed (P = 0.013) and “time” in changes in the Mini‐Mental State Examination (P < 0.001). Bodyweight showed a decreasing trend in the non‐frail group after 3 months, unlike in the frail group. For walking speed, moderate effect sizes (d = 0.67–0.74) were sustained over time in the frail group, as did lesser effect sizes (d = 0.26–0.40) in the non‐frail group. Conclusions Exercise‐based multicomponent interventions were effective for both groups. The longitudinal effects on walking speed and bodyweight were greater in the frail group. Geriatr Gerontol Int 2022; 22: 213–218.

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