CU Anschutz will be one of 29 sites participating in a phase 3 multi-site clinical research trial. The Interdisciplinary Movement Science Lab, led by Cory Christiansen PT, PhD will be coordinating the study for the Denver site. This study is designed to establish the efficacy of progressive high-intensity, endurance treadmill exercise to slow progression of the signs of Parkinson’s disease (PD) in those who have not yet initiated medication for PD. If successful, this study will have a significant impact on the quality of life of people with PD and their caregivers since it will slow progression of the signs of PD. Establishing high-intensity endurance treadmill exercise as a means to slow the progression of the signs of the disease would mark a significant breakthrough in treating PD and would have significant public health impact.