Nonlinear analysis of electromyogram following neuromuscular electrical stimulation-assisted gait training in stroke survivors

Abstract

Neuromuscular Electrical Stimulation (NMES) electrically activates the muscles of the lower extremities to assist walking following paralysis, which can either be triggered by a heel-switch (switch-trigger), or by an electromyogram (EMG)-based gait event detector (EMG-trigger). These NMES command sources were presented to each group of six chronic (>6 months post-stroke) hemiplegic stroke survivors. During the baseline and post-intervention surface EMG assessments, total 10 seconds of surface EMG was recorded from bilateral medial gastrocnemius muscles while the subjects tried to stand steady on their toes. Recurrence quantification analysis (RQA) was used to analyze the surface EMG based on two RQA parameters – the percentage of recurrence (%Rec) and determinism (%Det). The experimental results showed that the rate of change in %Rec and %Det significantly increased from baseline for the paretic muscle after EMG-triggered NMES-assisted gait training.