Motivated by reported improvements in aerobic fitness and executive functions after a 6-month aerobic walking intervention in normal sedentary elderly, we conducted a Phase I/II study to investigate effects of aerobic exercise on motor function, cognition, and quality of life in mild-moderate patients with Parkinson's disease (PD). To identify the best method to deliver fitness training, we also aimed to compare safety, tolerability, and fitness benefits between different training methods (continuous/moderate intensity vs. interval/alternating between low and vigorous intensity) and exercise settings (individual vs. group). Interval training reportedly facilitates higher fitness gains than continuous training. Group training may promote success through social interaction, whereas individual training offers greater flexibility.