Age and task-dependent modulations in EMG-EMG coherence during gait: a scoping review

Based on electromyography (EMG) recordings, EMG-EMG coherence provides a practical approach to investigate neural mechanisms involved in locomotion. Although some studies indicated the influence of age and walking conditions on EMG-EMG coherence, no clear consensus emerged from the existing literature. The aim of this scoping review was to map the literature on EMG-EMG coherence in healthy individuals across ages and walking tasks. Six databases (CINAHL, Cochrane Central, CDSR, MEDLINE, Embase, and Web of Science) were searched, resulting in 31 studies included (551 individuals). These studies analyzed EMG-EMG coherence of muscles involved during different locomotor tasks. The results revealed a consensus regarding the decrease in EMG-EMG coherence during walking with aging, particularly in the Beta and Gamma bands, which could be attributed to natural alterations in the corticospinal tract with age. Furthermore, Beta and Gamma EMG-EMG coherence showed an increased tendency during proprioceptive (perturbation-based tasks) and proactive (obstacle negotiation) locomotor tasks, which is interpreted as an enhancement of cortical involvement in gait control. This review also highlights the necessity for future research to examine EMG-EMG coherence in frequency bands such as Alpha using standardized signal processing techniques and frequency classifications, and to investigate coherence in children across various locomotor tasks.