Determine the short-term and lasting effects of intensity-matched exercise programs on level 2-3 PD patients' clinical symptoms, postural control, and mobility.

Hypothesis

1. The inclusion of a Borg-scale/heart-rate matched active control group will allow us to test the idea that, in addition to a fitness element, the reflexive movements that chellenge PD patients' sensorimotor system will improve patients' clinical symptoms, posture, and mobility more than fitness training and that such lasting effects will be superior in the agility compared with the fitness-control group. This hypothesis emered from the idea that the favorable results in the currently under review paper may be in part due to a simple conditioning effect instead of a specific motor learning effect caused by the xbox training.
2. If feasible, i.e., if there is a lerge enough pool of patients to randomize, a balance training group will be also added to test the idea that the reflexive actions evoked by the agility program by xbox exergaming still produce superior adaptations vs. the balance group because xbox forces patients to rapidly and reflexively execute movements (respond to cues, prompts), while balance training allows patients to stop, go, stop, and go and disrupt the continous execution of linked movements. The disruptions of movement chains could arise from small losses of balance on the unstabel surfaces, need for patients to re-initiate every movement element of a sequence, planning each movement element. It is not clear yet how it woul be possible to match all three intervention groups on Borg/heart rate intensity.

Agility: Xbox based high intensity program, as detailed in the submitted manuscript. Borg scale after after each exercise block is recorded. Heart rate continuosly measured. These data are used to set intensity in the fitness group.

Fitness: A stationary bicycle ergometer program that includes visual stimulation in the form of watching nature programs and movies to account for visual stimulus in Agility group. Mean heart rate and Borg scale readings from Agility group will form the target intensity.

Control: No-exercise, measurment-only control group.

Inclusion Criteria:

• Parkinson's disease,
• Hoenh Yahr scale of 2-3,
• instability problem,

Exclusion Criteria:

• Severe heart problems, severe demeanor, alcoholism, drug problems,