This study consists of two home-based exercise programs: a stationary exercise bicycle intervention (Arm A), and a walking intervention (Arm B). The study will enroll 24 patients who are starting ADT (Androgen Deprivation Therapy)/ARSI (Androgen-Receptor Signaling Inhibitors) therapy for newly diagnosed metastatic castrate-sensitive prostate cancer (mCSPC). All participants will be asked to complete 1-2 training sessions at UVA prior to starting the exercise. All participants will be asked to complete aerobic and strength testing before and after the exercise program. Participants will be asked to answer questionnaires throughout the program. The at-home exercise will last for 12 weeks.

The purpose of this study is to find out how many patients who are being treated for mCSPC complete one of two home-based exercise programs. The researchers want to find out how much exercise participants complete and how satisfied they are with the program. Another purpose of this study is to learn if doing the exercise changes fitness levels and/or muscle strength, and what relationship those changes might have on feeling tired during cancer treatment.

Participants will be randomly assigned (like the flip of a coin) to one of two home-based exercise programs:

• Arm A: A high intensity interval (HIIT) stationary bike program
• Arm B: A walking program

Participants in the cycling group (Arm A) will receive a stationary exercise bike for home exercise. All participants in the study (Arms A and B) will receive an activity monitor (watch) and a heart rate-monitoring chest strap that sends information back to the study team.

Participants will receive 1-2 exercise training sessions, held in a UVA research lab, to allow them to experience the level of the exercise they will be asked to complete. Each participant will make a personal plan with the study team to gradually workup to the exercise goal assigned to each group. The research team will answer any questions and help set up the activity monitors. After these session(s), the remaining 12 weeks of exercise will occur at home.

Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Male, aged ≥18 years old
4. Diagnosis of mCSPC (defined as either biopsy-proven metastatic prostate cancer or elevated PSA (Prostate Specific Antigen) in the setting of imaging findings typical of prostate cancer spread; patients can either have de novo metastatic disease or recurrent metastatic disease after prior definitive therapy to the primary tumor with either surgery or radiation)
5. Planned treatment with ADT (LHRH [Luteinizing hormone-releasing hormone] agonist such as leuprolide or LHRH antagonist such as degarelix), or recent administration, ≤14 days prior to enrollment.
6. Planned intensification with ARSI (abiraterone/prednisone, enzalutamide, apalutamide, or darolutamide).
7. Oncologist clearance for exercise training after taking into account functional status and co-morbid conditions that may limit ability to participate.
8. Ability to take oral medication and willing to adhere to the study intervention regimen
9. Ability to read, speak, and understand English.

Exclusion Criteria:

1. Castrate-resistant prostate cancer (defined as prostate cancer previously treated with a backbone of ADT hormonal therapy with either progression of disease on imaging PSA progression with PSA increase of > 25% and 2 ng/mL above nadir, confirmed at 2 time points at least 3 weeks apart, in the setting of testosterone level < 50)
2. Patients with prostate cancer with biochemical recurrence (e.g., received prior definitive therapy with subsequent PSA [Prostate-Specific Antigen] rise) but radiographic imaging is negative for metastatic disease
3. Metastatic bone lesion(s) in the proximal femur, bone lesion causing impending fracture, or other metastatic site deemed unsafe for walking by treating physician
4. Medical/orthopedic comorbidities that preclude stationary cycling or walking
5. Significant cardiac/renal/hepatic/hematological/pulmonary disease precluding exercise training
6. Unstable angina or myocardial infarction within 4-weeks prior to treatment
7. Complex ventricular arrhythmias or New York Heart Association class IV symptoms
8. Symptomatic severe aortic stenosis
9. Acute pulmonary embolus
10. Acute myocarditis
11. Untreated high-risk proliferative retinopathy
12. Recent retinal hemorrhage
13. Uncontrolled hypertension (systolic blood pressure > 180 mm Hg or diastolic blood pressure > 120 mm Hg)
14. Severe baseline electrolyte abnormalities (e.g. potassium) that may predispose patient to arrhythmias in the opinion of the treating investigator
15. Uncontrolled metabolic disease (diabetes with fasting blood sugar >300 mg/dl, thyrotoxicosis, myxedema)
16. Symptomatic peripheral vascular disease
17. Prior treatment with taxane- or platinum- based chemotherapy
18. Prior treatment with PARP [Poly (ADP-ribose) polymerase] inhibitors
19. Prior treatment with radium-223 or lutetium-177