Time-lapse changes in EEG-EMG coherence during weak voluntary contraction of the tibialis anterior muscle

Abstract

In this study, we investigated the relationship between EEG-EMG coherence and time-lapse changes during weak voluntary contraction of the tibialis anterior (TA) muscle. Eleven healthy men (21–29 years old) participated in the study. The subject was directed to contract his TA muscle for one minute at 10%, 15%, or 30% of maximum voluntary contraction by flexing his right tarsus. Each contraction was randomly performed and repeated five times. The relationships between each contraction level and the epoch number (1 epoch = 12 seconds) were analyzed. Peak coherence values increased significantly over time (p < 0.05). Moreover, the peak coherence value of the beta band changed significantly with time (p < 0.05). For contraction at 30%, the peak coherence appeared in the gamma band on the first and third epochs, while it was seen in the beta band on the second, fourth, and fifth epochs. A decrease in mean power frequency was observed over time. We observed significant differences in the voluntary contraction level (p < 0.05) in each epoch (p < 0.01). The fact that muscle fatigue and the maintenance of muscle contraction leads to synchronization of motor units suggests the activation of afferent feedback.