High intensity exercise for non-alcoholic steatohepatitis- is it safe, effective, and feasible in practice?

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Regular aerobic exercise has now been established as an effective therapy for reducing liver fat in patients with non-alcoholic fatty liver disease (NAFLD), even in the absence of weight loss. However the efficacy of regular exercise in progressive liver disease such as non-alcoholic steatohepatitis (NASH) is yet to be established. Recent evidence has suggested that high intensity exercise may be required for benefit and, as such, high intensity interval training (HIIT) may be an effective modality for improving cardiovascular, metabolic and liver health in patients with NASH. A key feature to the success of any exercise intervention is the ability to adhere to the intervention in the long-term. The ability to perform HIIT on a regular basis, in an unsupervised environment has yet to be determined. The aims are to i) examine the efficacy of a 12 week supervised exercise intervention involving high-intensity interval training (HIIT) in patients with biopsy-proven non-alcoholic steatohepatitis (NASH) for improving cardiorespiratory fitness (CRF), and ii) examine the safety and feasibility of regular HIIT in patients with NASH both when performed under supervision and when performed unsupervised (home-based, for 12 weeks). We hypothesise that, compared with control: i) the HIIT intervention will significantly improve CRF, and ii) the HIIT intervention will be safe and feasible for sustaining both supervised and unsupervised exercise adherence in people with NASH. Eligible participants (n=22) will be randomised into 12 weeks of HIIT (n=11) or a control (n=11). The primary analysis will examine the efficacy of 12 weeks of HIIT on changes in cardiorespiratory fitness, body composition, liver fat, liver stiffness, abdominal visceral fat, vascular function, and other cardio-metabolic risk factors, compared with control. The supervised HIIT training will begin with a warm-up for 5 min and at 60% of maximal heart rate (HRmax) followed by 4 x 4 min intervals at 85-95% HRmax interspersed with 3 min ‘recovery’ periods at 60% HRmax, then a 5 min cool down. Participants randomised to the control group will perform 12 weeks of stretching and then be invited to complete the HIIT protocol. On completion of the HIIT intervention, all participants (n=22) will be prescribed an on-going exercise program based on an equivalent type and intensity of exercise, modified for an unsupervised home/gym environment. Feasibility and adherence will be assessed via self-administered questionnaires and focus group after 12 weeks of home based exercise.