The purpose of this study is to determine if the 9zest app for Parkinson's disease is feasible, safe, and efficacious when used independently by individuals with Parkinson's disease.

The investigators will evaluate the 9zest app using a non-randomized, single-group design wherein participants who have downloaded the 9zest app will be informed via a message in the app about the trial and invited to participate. If the participant answers yes to the invitation the participant will be consented through a questionnaire in the app. In the consent form for participation, prospective participants will learn the eligibility criteria. If the participant completes the informed consent process, the participant will then be required to answer specific inclusion and exclusion criteria questions to ensure qualification for the study. A phone number that goes directly to a member of the research team will be provided if the prospective participant has any questions during the informed consent process.

Outcome measurements. After completing the consent process and prior to participation in the 12-week trial, participants will answer several questions about specific symptoms to complete their registration and profile. The participant will then be asked to perform a couple of pretest outcome measures via the app. Participants will also be tested at the 4 week, 8 week, and 12 week marks.

Exercise intervention. The 12-week app guided exercise intervention is a personalized exercise regimen. Participants will use the smartphone/tablet app for the study period of 12 weeks. While the app has been developed to deliver physical therapy in a variety of movement disorders including multiple system atrophy, progressive supranuclear palsy, and dementia with Lewy bodies, users will choose the PD track for the purposes of the study, which is the population of interest. The participants will create a PD profile with a series of questions to assess the current level of functioning. A proprietary algorithm (9zest Smart™) developed by physical therapists and information technologists chooses the appropriate workout regimen for the person's level of function. The customized regimen is intended to be safe and effective for the participant. The 9zest App Family has over 1,000 original therapy videos in its library, which encompasses Physical Therapy, Fitness, Yoga, Meditation, and Speech Therapy. 9zest Smart™, the app's intelligent engine determines the right set and levels of exercises for a user based on the Smart Assessment responses. At preset intervals (generally after 2 weeks), the app will again assess the user's functional capacity and needs. Again, the 9zest Smart algorithm will adjust the type, duration, and intensity of the regimen to maximize performance. All of the exercises and dosing features are consistent with contemporary and evidence-based physical therapy practice. Additionally, the exercises have all been deemed to be safe by physical therapists for each particular level of function. The exercise program is imbedded in the app. A demonstration of the exercise is shown in audiovisual format and then the participant follows along with the exercise in real time.

Participants in the trial will be asked to participate in the 12-week exercise program with the goal of participating 3 times per week with each session lasting 60 minutes. After the trail is over, the investigators will sort and analyze the data based on compliance (eg, high engagers, moderate engagers, low engagers).

Inclusion Criteria:

• English speaking men and women between 40 and 75 years old
• Neurologist-diagnosed PD
• A caregiver who is willing to assist the participant
• Willingness to participate is a 12 week study
• Be able to stand unassisted for 10 minutes
• Stable on PD medication and deep brain stimulation for 3 months prior to trial

Exclusion Criteria:

• Failure on a cognition screen
• Co-morbidities that would preclude exercise participation or increase participant risk: severe osteoarthritis/pain, stroke, severe respiratory problems, traumatic brain injury, neuromuscular disease, atrial fibrillation, poorly controlled cardiovascular disease, limb amputation, osteoporosis)
• Vision or hearing impairment that would interfere with app use
• Fall that required physician evaluation (ED, urgent care, hospitalization) with the past year
• Use of an assistive device (or person) for walking, standing, balance.
• Currently use of a structured exercise regimen defined as participation in a regular exercise program consisting of more than 60 minutes per week in total