Inclusion Criteria:  Diagnosis of Parkinson's disease following the UK Brain Bank Diagnostic Criteria, Hoehn and Yahr stages II-III, 45-75 years old, Able to ride a stationary upright bicycle, Able to sign informed consent.  Exclusion Criteria:  Have a recent history of severe heart disease, severe lung disease, uncontrolled diabetes, traumatic brain injury or neurological disorder other than Parkinson Disease, Are unable to follow directions or sign a consent form, Do not have adequate vision or hearing ability to see or hear a television, Have unstable medical condition or musculoskeletal disorder such as severe arthritis, recent knee surgery, hip surgery, or any other condition that the investigators determine would impair the ability to ride the bicycle, Have any other medical condition that prevents bicycling, Have moderate depression (score of 9 or more on GDS screening tool).