Association of gait recovery with intramuscular coherence of the Vastus medialis muscle during assisted gait in subacute stroke.

Objectives: We aimed to investigate the effect of descending neural drive during assisted gait training on gait recovery in non-ambulatory stroke patients and the effect of 1-month gait training on the descending neural drive.

Methods: Twenty stroke patients unable to walk independently were included in this longitudinal study. Intermuscular coherence analysis (beta band; 15-30 Hz) was performed on electromyography signals recorded from the proximal and distal segments of the vastus medialis (VM) and lateral hamstring (LH) on the paretic side (i.e., VM-VM, VM-LH, and LH-LH coherence) during assisted gait used knee-ankle foot orthosis. Lower limb flexion and extension angles and step count during training were also assessed. Gait recovery was assessed by the number of days required to achieve functional ambulation category (FAC) 3 (supervised gait) since stroke onset. The participants were then classified into the FAC 3-achieved and FAC 3-not achieved groups.

Results: Days to achieve FAC 3 was significantly associated with VM-VM coherence in the beta band (ρ = -0.648, p = 0.003). VM-VM coherence in the beta band during assisted gait significantly increased in the FAC 3-achieved group than in the FAC 3-not achieved group. In contrast, VM-LH and LH-LH coherence were not significantly associated with the days to achieve FAC3 and were not significantly increased by training.

Conclusion: Stroke survivors who were unable to walk independently but had reacquired supervised gait exhibited high VM-VM coherence, which increased with gait training. This finding indicates the presence of residual descending neural drive related to weight acceptance.