Volitional modulation of beta-band EMG coherence through frequency-specific neurofeedback

Electromyography (EMG) feedback, which records and visually presents muscle activity, has been widely employed to enhance motor control and support rehabilitation. While its effectiveness has been demonstrated across various conditions, most EMG feedback protocols have focused on modulating activity in individual muscles, with limited emphasis on promoting coordinated neuromuscular control. This study investigated the feasibility of enhancing neuromuscular coordination through feedback training designed to increase beta band (15-35 Hz) intramuscular coherence. Twenty-two healthy participants were randomized into two groups: a Real group, receiving visual feedback based on beta-band coherence, and a Sham group, receiving feedback derived from pseudo-EMG signals (recorded EMG with randomized time-series noise). Both groups completed dorsiflexion exercises over five days. Linear mixed-effects modeling revealed a significant increase in beta-band coherence in the Real group compared to the Sham group, demonstrating the efficacy of feedback training in modulating neural synchronization. However, no significant improvements in motor performance were observed, and perceived controllability of coherence did not correlate with actual physiological changes. Mental fatigue remained similar between groups, suggesting low cognitive burden from the training. These findings underscore the potential of frequency-specific EMG coherence feedback as a novel neuromodulation approach, while highlighting the need for further refinement to achieve functional improvements and expand its clinical utility.