Using Cortico-Muscular and Cortico-Cardiac Coherence to Study the Role of the Brain in the Development of Muscular Fatigue

We propose a method to analyze cortico-muscular and cortico-cardiac coupling during a cycling exercise in order to study the development of muscular fatigue. Our analysis is based in finding statistically significant changes in the coherence between electromyography (EMG) and electrocardiography (ECG) when compared against electroencephalography (EEG) signals. The coherence is a measure of the degree of correlation of the spectral power in an specified bandwidth between two signals, then EMG-EEG and ECG-EEG coherences are here analyzed during the development of muscular fatigue. For that purpose, we propose an experimental protocol in which a personalized fatigue threshold is found for the volunteers, then different levels of physical exertion are considered. Our results showed significant changes in the maximum cortico-muscular coherence in the beta brain rhythm as the exercise progresses and fatigue develops, as well as changes in the maximum cortico-cardiac coherence, again in the beta band, from the beginning to the end of the exercise protocol. (C) 2018 Elsevier Ltd. All rights reserved.