Introducing EL-FIT (Exercise and Liver FITness): A Smartphone App to Prehabilitate and Monitor Liver Transplant Candidates.

Preserved physical function is key for successful liver transplantation (LT); however, prehabilitation strategies are underdeveloped. We created a smartphone application (app), EL‐FIT (Exercise and Liver FITness), to facilitate exercise training in end‐stage liver disease (ESLD). In this feasibility study, we tested EL‐FIT app usage and the accuracy of physical activity data transfer and obtained feedback from initial users. A total of 28 participants used the EL‐FIT app and wore a physical activity tracker for 38 ± 12 days (age, 60 ± 8 years; 57% males; Model for End‐Stage Liver Disease–sodium, 19 ± 5). There was fidelity in data transfer from the tracker to the EL‐FIT app. Participants were sedentary (1957 [interquartile range, 873‐4643] steps/day) at baseline. Level of training assigned by the EL‐FIT app agreed with that from a physical therapist in 89% of cases. Participants interacted with all app features (videos, perceived exertion, and gamification/motivational features). We rearranged training data to generate heart rate–validated steps as a marker of performance and showed that 35% of the participants had significant increases in their physical performance. Participants emphasized their interest in having choices to better engage in exercise, and they appreciated the sense of community the EL‐FIT app generated. We showed that patients with ESLD are able to use and interact with the EL‐FIT app. This novel smartphone app has the potential of becoming an invaluable tool for home‐based prehabilitation in LT candidates.