The overall objective of this study is to determine the futility or non-futility of conducting a randomized controlled trial to determine the effects of exercise on the progression of PD symptoms. The primary aim is to determine whether individuals with de novo Parkinson's disease (naïve to drug treatment) can achieve the randomly assigned levels of mean exercise intensity (60-65% HRmax or 80-85% HRmax) and adhere to the exercise protocol.
Inclusion Criteria: - Clinical diagnosis of primary Parkinson's disease - In a Hoehn and Yahr stage less than stage III - Disease duration is less than 5 years - Not likely to require dopaminergic therapy within 6 months Exclusion Criteria: - Use of any PD medication within 60 days prior to the beginning the study, including levodopa, direct dopamine agonists, amantadine, Rasagiline (Azilect), Selegiline (Eldepryl), Artane (trihexyphenidyl). - Duration of previous use of medications for PD that exceeds 90 days - Expected to require dopaminergic therapy in the next 6 months - Poorly controlled or unstable cardiovascular disease - Uncontrolled hypertension - Hypo- or hyperthyroidism, abnormal liver function, abnormal renal function - Mild cognitive impairment (Montreal Cognitive Assessment score<26/30) - Depression that precludes ability to exercise (Beck depression score>13) - Disorders that interfere with ability to perform endurance exercises - Regular participation in vigorous endurance exercise - Evidence of serious arrhythmias or ischemic heart disease - Any clinically significant medical condition, psychiatric condition, drug or alcohol abuse, or laboratory abnormality that would, in the judgment of the investigators, interfere with the ability to participate in the study