PROJECT SUMMARY/ABSTRACT Despite advances in pharmaceutical and surgical approaches to the treatment of Parkinson’s disease (PD), an effective disease modifying treatment remains elusive. A growing body of evidence supports the notion that high intensity aerobic exercise, when delivered in a highly supervised, well-controlled laboratory setting, improves PD symptomology. Despite community exercise being recommended by the American Physical Therapy Association, high intensity aerobic exercise performed in a community-setting is not supported by third party payors and therefore not delivered by physical therapists. The aim of this project is to address two fundamental gaps related to the widespread utilization of exercise to modify PD: 1) are community-based exercise programs effective in altering disease progression? and 2) what is the role of genetics in modulating the disease altering effects of high intensity aerobic exercise? Our underlying hypothesis is that high-intensity community-based exercise is effective in slowing disease progression in PD and those positive effects are more likely to occur in individuals with a lower genetic\biological burden. The proposed multi-site, Genetics and Aerobic Exercise to Slow (GEARS) PD trial will determine the interplay between genetics and exercise in altering PD progression. A total of 250 individuals with PD will be enrolled in Pedaling for Parkinson’s (PFP) programs across six locations in NE Ohio and Salt Lake City. The PFP exercise protocol is rooted in our established and effective laboratory-based exercise protocol for PD (e.g. exercise at 60-80% of heart rate reserve and strive to pedal at 75 RPMs). The PFP community group will exercise 3 times per week for 12 months. A novel and efficient aspect of the GEARS Trial is the leveraging of PD control data (n=125) from Dr. Alberts’ CYCLE-II RCT (2R01NS073717; enrollment completed March 2022). Identical clinical and biomechanical data characterizing motor and non-motor f