Corticomuscular Coupling Analysis of Dynamic Balance During Eccentric and Concentric Muscle Contractions

Maintaining body balance, which involves both eccentric and concentric muscle contraction during body movement, is crucial in daily life. However, the neural mechanisms underlying eccentric and concentric muscle contractions in dynamic balance remain unclear. In this study, electroencephalography and electromyography signals were collected from 11 healthy males performing a heel-lifting task under various conditions. The wavelet packet transfer entropy was used to analyze the changes in corticomuscular connectivity during different levels of balance difficulty and muscle contractions. Electroencephalography-electromyography coupling values were higher in the gamma band than at other frequencies. In the alpha and beta bands, transfer entropy values were higher from the brain to the muscles, whereas in the gamma band, these values were higher in the opposite direction. During single-foot heel maneuvers, transfer entropy values were higher in the lowering task and greater during right-footed heel lowering than during left-footed heel lowering. Cortical-muscle connections were strengthened in the gamma band with increased balance difficulty. Additionally, eccentric muscle contractions demonstrated stronger cortical-muscle coupling than concentric contractions, with muscles exerting greater influence on the cortex. These findings enhance our comprehension of the neural mechanisms that underlying dynamic balance during muscle contractions.