Comparison of Cardiorespiratory Fitness Among Regular Exercisers With and Without Parkinson Disease and Across Different Modes of Group Exercise

Inclusion Criteria: * All participants included in this study must be between the ages of 55 and 75 * Be able to ambulate independently without physical assistance, assistive device, or lower extremity orthosis * Be able to follow at least 3-step verbal commands * Participate in a community-based group exercise program * Be classified as regular exercisers by participating in 120 minutes per week for at least 3 months * And have a physician's consent to undergo a graded exercise test (GXT). * Furthermore, only participants that are identified as low or moderate risk for cardiovascular disease based on ACSM's risk stratification guidelines will be included in the study. * Participants for the two PD groups must have a diagnosis of idiopathic PD * Have a Hoehn-Yahr score of 1, 2, or 3 * And either participate regularly in boxing training at Rock Steady Boxing or participate in another community-based group exercise program on a regular basis, classified as 120 minutes per week for at least 3 months. Exclusion Criteria: * Participants may not be included in the study if they have had any surgery in the past 6 months * Current musculoskeletal or complications from other health issues that influence walking. * The participants without disability cannot be involved in the study if they have any preexisting neurological conditions. * Participants with PD cannot be involved in the study if they have preexisting neurological conditions other than idiopathic PD (e.g. no diagnosis of Parkinson Plus syndrome), past brain surgery or implantation of a deep brain stimulator.