Review article: impact of exercise on physical frailty in patients with chronic liver disease

Background Physical frailty is common in chronic liver disease and the setting of liver transplantation. It is associated with poor quality of life, increased hospitalisation and mortality. Despite this, the impact of exercise in these patients remains poorly understood. Aim To summarise the impact of physical exercise on physical frailty in patients with chronic liver disease until after liver transplantation. Methods A MEDLINE and PubMed search was undertaken using the terms; physical activity, functional capacity, exercise, prehabilitation, frailty, liver cirrhosis, liver failure, liver transplantation chronic liver disease and end-stage liver disease from January 1990 to June 2019. Results Eleven studies (five randomised controlled, five observational, one case study) demonstrated that exercise improves VO2 peak, anaerobic threshold, 6-minute walk distance, muscle mass/function and quality of life in patients with compensated and decompensated cirrhosis. Improvements were most significant with a combination of aerobic and resistance exercises at moderate-high intensity. The studies were small (n = 1-50) and mainly focused on supervised, hospital-based exercises, excluding patients with significant liver failure (MELD > 12). Seven studies (four randomised controlled and three observational) demonstrated that predominantly supervised (only one home-based) aerobic exercise after liver transplantation improves aerobic capacity, muscle mass/strength and quality of life. There was marked heterogeneity in timing, intensity and type of exercises. Conclusion Exercise improves key components of physical frailty (functional/aerobic capacity, sarcopenia) and quality of life in chronic liver disease and after liver transplantation. Understanding the type, compliance, intensity and duration of exercise and its impact on hard clinical outcomes should be the focus of future large controlled clinical trials.