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.