Introducing EL‐FIT (Exercise & 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 app, EL-FIT (Exercise & Liver FITness), to facilitate exercise training in end-stage liver disease (ESLD). In this feasibility study, we tested EL-FIT app usage, accuracy of physical activity data transfer, and obtained feedback from initial users. Twenty-eight subjects used EL-FIT and wore a physical activity tracker for 38±12 days (age 60±8 years, 57% males, MELDNa 19±5). There was fidelity in data transfer from tracker to EL-FIT. Participants were sedentary (1957 [IQR: 873-4643] steps/day) at baseline. Level of training assigned by EL-FIT agreed with that from a physical therapist in 93% 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 subjects had a significant increase in their physical performance. Participants emphasized their interest in having choices to better engage in exercise and they appreciated the sense of community EL-FIT generated. Conclusion: We showed that ESLD patients are able to use and interact with EL-FIT. This novel smartphone app has the potential of becoming an invaluable tool for home-based prehabilitation in LT candidates.