The goal of this clinical trial is to learn whether training with blood flow restriction (BFR), combined with aerobic exercise (performing stepping on a Nu-Step exercise machine), can help improve mobility and other outcomes in people with progressed Parkinson's disease. The investigators hypothesize that training with BFR and aerobic exercise will produce enhanced outcomes related to mobility and quality of life.

BFR uses inflatable cuffs placed on participants' upper legs to gently reduce blood flow to the legs while exercising. This has been shown in studies in older adults and Parkinson's disease to improve strength while training with lighter loads, which may be helpful for people with Parkinson's.

Participants will be asked to complete 2 weekly training sessions (approximately 30 minutes each) for 8 weeks consisting of supervised aerobic stepping exercise on a Nu-step machine with BFR application during timed intervals. In addition to the training sessions, participants will be asked to periodically perform confidential surveys and tests related to function and disease symptoms, and wear a provided smartwatch (which can be kept upon successful completion of the study). All sessions involve individual monitoring and medical supervision by licensed physical therapists as well as access to all necessary equipment.

This study's primary objective is to determine the exploratory safety of the combined recumbent stepping + BFR intervention for this population. Secondary aims are to evaluate the exploratory efficacy on the intervention for Parkinson's symptoms including functional mobility, autonomic function, daily step counts, cognition, and quality of life, as well as obtain feasibility and acceptability of the intervention from participants.

This is a pilot clinical trial (pre-post) which will investigate the safety, feasibility, and exploratory effectiveness of a novel, 8-week clinical trial with BFR + low-intensity recumbent stepping for advanced PD in 4 participants. Data will be collected at three time-points: baseline, after the 8-week intervention, and at 4-weeks post-intervention cessation to assess for continued longitudinal intervention effects and short-term durability. Findings will guide optimization, scalability, and future clinical implementation via larger randomized controlled trials and protocol refinement as appropriate.

Screening, consent, and baseline assessments will be conducted individually with the PI; all participants will continue their prescribed Parkinson's medications during the study. Participants will be given a fitness tracker watch and training as needed, then complete the 8-week intervention with continuous monitoring by one of the investigators using heart rate, SpO2, rate of perceived exertion (RPE), and blood pressure (BP) taken before and/or during and after the intervention.

BFR Intervention Details: Participants will perform recumbent stepping (legs only) using a Nu-Step machine as detailed above, with Fit Cuffs®' BFR straps wrapped around their bilateral proximal thighs at 40% arterial occlusion pressure (remaining consistent throughout the protocol). The arterial occlusion pressure at rest (rAOP) will be assessed using a FitCuffs® pressure system and pulse oximeter. The cuffs will be inflated until the distal pulse (measured at the toe) is no longer detectable. The corresponding pressure will be recorded as the rAOP and used to calculate the BFR training pressure at 40% rAOP. In the case of issue using the device, a doppler ultrasound will be used at the dorsalis pedis artery to check for occlusion and associated pressure.

Weekly surveys will be emailed to participants for input of their daily (averaged) step counts during that week, falls, heart rate variability, and feedback regarding the intervention, with participant follow-up performed by the investigators as appropriate.

Inclusion Criteria:

1. Age 18+
2. People with advanced Parkinson's disease. "Advanced PD" will include signs of progressed disease including orthostatic hypotension and/or motor issues reflective of postural instability and/or mild-moderate bilateral symptoms (confirmed visually in clinic or home by a medical provider such as an MD/PT and/or documented in the medical record.
3. Ability of individual or legal guardian/representative to understand a written informed consent document, and the willingness to sign it.
4. Diagnosis of idiopathic Parkinson's disease (self-reported okay, documented preferred)
5. Independent ambulation (≥10m with or without an assistive device)
6. Commitment to participate in the exercise intervention as outlined
7. Score of ≥21 on the Montreal Cognitive Assessment (MoCA)

Exclusion Criteria:

1. History of cardiovascular disease, uncontrolled hypertension (blood pressure

   ≥140/90 mmHg), deep-vein thrombosis, varicose veins, or rhabdomyolysis which a patient's primary physician determines would preclude them from safe study participation.

2. Ankle branchial index ≤ 0.9 or > 1.3

3. History of or comorbid conditions spanning cardiovascular, neurological, or orthopedic injuries which may prevent for the safe administration of the intervention (a healthcare provider's clearance or guidance will be obtained in these situations to ensure appropriateness), including current medications.

4. History of uncontrolled diabetes, BMI > 40, or severe cognitive impairment (as measured by MoCA <21)

5. Atypical PD diagnoses or ON PD-medication worsening of motor symptoms

6. Absolute contraindications to exercise as per the American College of Sports Medicine (uncontrolled arrhythmias, third-degree heart block, recent electrocardiogram (EKG) changes, unstable angina, acute myocardial infarction, or acute congestive heart failure)

Aggregated participant data which has been de-identified; likely provided through descriptive statistics and aggregated results only, due to the relatively small sample size to prevent potential identification.

Within 6 months following study completion.

Researchers and other interested parties will be asked to contact the PI via email. Data will only be shared as detailed above (aggregated, de-identified data) in alignment with UCSF IRB protocol.