Cycling in Parkinson's Disease

Inclusion Criteria: * Idiopathic Parkinson's Disease * Hoehn and Yahr Stages II - III. * Ages 30-80 years * Medical Clearance * Ability to understand and the willingness to sign a written informed consent. Exclusion Criteria: * MOCA: (Montreal Cognition Scale) : rating of less than 24, indicative of cognitive dysfunction * Changes in Parkinson's medications within the two weeks prior to starting the study * Anticipated change in Parkinson Disease medications during the course of the study * Uncontrolled orthostasis * Symptomatic coronary artery disease * Fracture of lower limb within 6 months prior to study onset or significant lower limb orthopedic diagnosis that would limit cycling * Other significant neurologic diagnoses including multiple sclerosis or vestibular disease * Acute illness * Physical therapy within the month prior to study entry * Subjects already participating in a forced exercise or high intensity exercise program * Any medical condition that the physician investigator determined would compromise safety.