Home-based exercise and PHysical activity maintenance interventiOn after livEr traNsplantation: Impact of eXercise intensity (PHOENIX-Liver).

Abstract

Liver transplant recipients experience comorbidities, including impaired physical fitness, which could be managed by exercise and physical activity interventions. This study aims to evaluate the feasibility, clinical effectiveness and cost-effectiveness of a 6-month exercise intervention, followed by a 15-month tailored physical activity maintenance intervention, in de novo liver transplant recipients. This single-centre, randomised, controlled, single-blinded trial will recruit 147 adult liver transplant recipients at 3-5 months post-transplant. Participants will be randomised into (1) 6 months of enhanced usual care, not followed by a physical activity intervention (control (CON) group, n=49), (2) 6 months of moderate-intensity exercise training, followed by a physical activity intervention (moderate-intensity training (MIT) group; n=49) or (3) consecutively 3 months of moderate-intensity exercise training, 3 months of high-intensity interval training and a physical activity intervention (moderate and high-intensity training (MHIT) group; n=49). Exercise training will consist of home-based stationary bicycling and muscle-strengthening exercises, partially supervised by participants' local physiotherapists. The physical activity intervention includes an array of behaviour change techniques. Primary hypothesis: after the exercise intervention, peak oxygen uptake (V̇O₂peak) will be higher in MHIT versus CON (α-level 0.05). Secondary hypotheses: after the exercise intervention, V̇O₂peak will be higher in MIT versus CON and MHIT versus MIT (α-level 0.025). Secondary outcomes, assessed up to 2 years post-transplant, include physical fitness, cardiovascular and graft health, quality of life, physical activity and implementation outcomes. Trial registration number NCT06302205.