High-Intensity Interval Training is Safe, Feasible and Efficacious in Nonalcoholic Steatohepatitis: A Randomized Controlled Trial

BACKGROUND: High-Intensity Interval Training (HIIT) involves bursts of high-intensity exercise interspersed with lower-intensity exercise recovery. HIIT may benefit cardiometabolic health in people with nonalcoholic steatohepatitis (NASH). AIMS: We aimed to examine the safety, feasibility, and efficacy of 12-weeks of supervised HIIT compared with a sham-exercise control (CON) for improving aerobic fitness and peripheral insulin sensitivity in biopsy-proven NASH. METHODS: Participants based in the community [(n = 14, 56 ± 10 years, BMI 39.2 ± 6.7 kg/m(2), 64% male), NAFLD Activity Score 5 (range 3–7)] were randomized to 12-weeks of supervised HIIT (n = 8, 4 × 4 min at 85–95% maximal heart rate, interspersed with 3 min active recovery; 3 days/week) or CON (n = 6, stretching; 3 days/week). Safety (adverse events) and feasibility determined as ≥ 70% program completion and ≥ 70% global adherence (including session attendance, interval intensity adherence, and duration adherence) were assessed. Changes in cardiorespiratory fitness (V̇O(2)peak), exercise capacity (time-on-test) and peripheral insulin sensitivity (euglycemic hyperinsulinemic clamp) were assessed. Data were analysed using ANCOVA with baseline value as the covariate. RESULTS: There were no HIIT-related adverse events and HIIT was globally feasible [program completion 75%, global adherence 100% (including adherence to session 95.4 ± 7.3%, interval intensity 95.3 ± 6.0% and duration 96.8 ± 2.4%)]. A large between-group effect was observed for exercise capacity [mean difference 134.2 s (95% CI 19.8, 248.6 s), ƞ(2) 0.44, p = 0.03], improving in HIIT (106.2 ± 97.5 s) but not CON (− 33.4 ± 43.3 s), and for peripheral insulin sensitivity [mean difference 3.4 mg/KgLegFFM/min (95% CI 0.9,6.8 mg/KgLegFFM/min), ƞ(2) 0.32, p = 0.046], improving in HIIT (1.0 ± 0.8 mg/KgLegFFM/min) but not CON (− 3.1 ± 1.2 mg/KgLegFFM/min). CONCLUSIONS: HIIT is safe, feasible and efficacious for improving exercise capacity and peripheral insulin sensitivity in people with NASH. CLINICAL TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trial Registry (anzctr.org.au) identifier ACTRN12616000305426 (09/03/2016). GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10620-022-07779-z.