Parkinson’s disease (PD) is a progressive neurodegenerative disease with diverse motor and non- motor symptoms. Although the primary neuropathology and symptoms of PD have been well established, the physiological mechanisms behind specific kinematic abnormalities are not well understood. Many such abnormalities (e.g., gait disturbances) can significantly impact a person’s quality of life. One way that PD may affect movement is through its connection with the motor cortex. In a series of experimental studies, I have examined whether the communication between the cortex and active muscles (corticomuscular communication) is affected by PD during anti-phasic cyclical ankle movements. To quantify such communication, coherence was calculated between cortical and muscle activities (corticomuscular coherence). The results from these studies suggest that i) the midline cortical areas are functionally involved in the cyclical ankle movements, ii) the corticomuscular communication may be affected by compensation against aging-related neuromuscular changes, and iii) the performance of the cyclical ankle movements is impaired by PD although the kinematic abnormalities were not accompanied by changes in the corticomuscular communication. To better understand how aging and PD affect the corticomuscular communication, future studies should examine the relevant neural correlates of movement in a more comprehensive manner (i.e., including subcortical structures). To my knowledge, these studies are the first to demonstrate that simple cyclical ankle movements are accompanied by dynamic changes in corticomuscular coherence and to examine how such coherence is affected by aging and PD.