This study is for people with Parkinson's disease (PD) who have a device called Deep Brain Stimulation (DBS) to help with their symptoms. Parkinson's disease is a condition that affects your movement and thinking. The study wants to see how two types of biking exercise, called forced exercise (FE) and voluntary exercise (VE), help people with PD. Forced exercise uses a motor to help you pedal faster, while voluntary exercise lets you pedal at your own pace.

Over 8 weeks, 36 participants will either do forced or voluntary cycling. The study will measure how well people move, think, and how their brain works. It will use EEG (a test that checks brain activity) and the DBS device to get information about the brain.

To be part of the study, you need to be able to walk for 5 minutes with or without help and be willing to pause your PD medication and DBS for testing. You cannot join if you have other brain diseases or certain health issues.

• Study lasts 8 weeks with exercises and a delayed start period.
• Participants must have a DBS device and be able to walk for 5 minutes.
• Medical clearance might be needed for some participants.