The goal of this clinical trial is to evaluate the effects of a home-based exercise program using mobile technology on physical activity and capacity, frailty and muscle mass, and quality of life in patients with a newly implanted HeartMate 3 left ventricular assist device (HM3 LVAD). Researchers will compare the effects of an exercise intervention vs. usual care on physical activity and capacity, frailty and muscle mass, and quality of life.

Eligible subjects who sign the consent form will be randomized to either the exercise intervention arm or the usual care arm. As part of the baseline assessment, all subjects will measure their average daily steps during week 1 using a Garmin activity tracking watch, complete a six-minute walk test, complete frailty testing (including measurements of handgrip strength and gait speed), and complete surveys. Subjects will also complete a CT scan to evaluate muscle mass. After completing baseline assessments, subjects will be randomized to one of the study arms.

Subjects in the usual care arm will receive a Garmin activity tracking watch to wear continuously. Subjects will receive reminders from a smartphone app (Datos) to wear the watch. Subjects will be encouraged to increase daily walking as tolerated. In addition to standard of care clinic visits, they will receive phone calls from the study research coordinator reminding them to wear the watch and to walk.

Subjects in the exercise intervention arm will first have an initial training session with an interventionist to review exercises and safe practices. Subjects will receive an individualized exercise prescription for frequency, duration, and intensity of walking and strengthening exercises (including use of resistance bands and light weights). Subjects' progress in the exercise program will be remotely monitored using the activity tracking watch and the smartphone app, and subjects will complete questionnaires through the app. Subjects will complete video calls with the interventionist throughout the duration of the study and will receive updated personalized exercise prescriptions based on their progress.

Subjects in both study arms will have regular follow up VAD Clinic appointments per standard of care practices. Subjects will complete questionnaires, complete six-minute walk testing, complete frailty testing (including measurements of handgrip strength and gait speed), and undergo a chest CT scan without contrast as part of follow up activities. Throughout the study, data will be collected from the medical record.

Inclusion Criteria:

1. ≥ 18 years of age
2. Newly implanted with a HeartMate 3™ LVAD for the first time
3. Able to ambulate independently (with or without the use of an assistive device)
4. Owns a smartphone with Internet connection
5. Patient will be discharged home with LVAD or patient will be living at home with LVAD within 45 days of index discharge

Exclusion Criteria:

1. Major comorbidities or limitations that may interfere with exercise training (including significant orthopedic/neurologic limitations, decompensated heart failure, uncontrolled arrhythmias, unstable angina)