Electrophysiological approaches to understanding brain-muscle interactions during gait: a systematic review

Objective: This study systematically reviews the role of the cortex in gait control by analyzing connectivity between electroencephalography (EEG) and electromyography (EMG) signals, i.e. neuromuscular connectivity (NMC) during walking. We aim to answer the following questions: (i) Is there significant NMC during gait in a healthy population? (ii) Is NMC modulated by gait task specifications (e.g. speed, surface, additional task demands)? (iii) Is NMC altered in the elderly or a population affected by a neuromuscular or neurologic disorder? Methods: Following PRISMA guidelines, a systematic search of seven scientific databases was conducted until September 2023. Results: Out of 1308 identified papers, 27 studies met the eligibility criteria. Despite large variability in methodology, significant NMC was detected in most of the studies. NMC was able to discriminate between a healthy population and a population affected by a neuromuscular or neurologic disorder. Tasks requiring higher sensorimotor control resulted in an elevated level of NMC. Conclusions: While NMC holds promise as a metric for advancing our comprehension of brain-muscle interactions during gait, aligning methodologies across studies is imperative. Significance: Analysis of NMC provides valuable insights for the understanding of neural control of movement, development of gait retraining programs and contributes to advancements in neurotechnology.