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The Effect of High-intensity Interval Training vs Moderate-intensity Continuous Training on Liver Fat: A Systematic Review and Meta-Analysis.

NICM Health Research Institute, Western Sydney University, Westmead, New South Wales 2145, Australia. School of Health Sciences, Western Sydney University, Campbelltown, New South Wales 2560, Australia. Medical Research Institute of New Zealand (MRINZ), Newtown, Wellington 6021, New Zealand. Discipline of Exercise and Sport Science, Faculty of Medicine and Health, The University of Sydney, Camperdown, New South Wales 2006, Australia. Greg Brown Diabetes & Endocrinology Research Laboratory, Charles Perkins Centre, Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, New South Wales 2006Australia. Department of Endocrinology, Royal Prince Alfred Hospital, Camperdown, New South Wales 2050, Australia. Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia. Storr Liver Centre, Westmead Institute for Medical Research and Westmead Hospital, The University of Sydney, Westmead, New South Wales 2145, Australia. Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales 2006, Australia.

The Journal of clinical endocrinology and metabolism. 2022;(3):862-881
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Abstract

CONTEXT Non-alcoholic fatty liver disease, characterized by excess fat accumulation in the liver, is considered the hepatic manifestation of metabolic syndrome. Recent findings have shown that high-intensity interval training (HIIT) can reduce liver fat but it is unclear whether this form of exercise is superior to traditional moderate-intensity continuous training (MICT). OBJECTIVE The aim of this systematic review was to determine the effect of HIIT vs MICT on liver fat in adults. A secondary aim was to investigate the interaction between total weekly exercise volume and exercise-related energy expenditure and change in liver fat. METHODS Relevant databases were searched up to December 2020 for randomized trials, comparing HIIT to control, MICT to control, or HIIT to MICT. Studies were excluded if they did not implement 2 or more weeks' intervention or assess liver fat using magnetic resonance-based techniques. Weighted mean differences and 95% CIs were calculated. Regression analyses were undertaken to determine the interaction between weekly exercise volume in minutes and kilocalories (kcal) with change in liver fat content. RESULTS Of the 28 268 studies screened, 19 were included involving 745 participants. HIIT and MICT both elicited moderate reductions in liver fat content when compared to control (HIIT: -2.85%, 95% CI, -4.86 to -0.84, P = .005, I2 = 0%, n = 114, low-certainty evidence; MICT -3.14%, 95% CI, -4.45 to -1.82, P < .001, I2 = 5.2%, n = 533, moderate-certainty evidence). There was no difference between HIIT and MICT (-0.34%, 95% CI, -2.20 to 1.52, P = .721, I2 = 0%, n = 177, moderate-certainty evidence). Neither total exercise volume in minutes (β = .0002, SE = 0.0017, Z = 0.13, P = .89) nor exercise-related energy expenditure in kcal (β = .0003, SE = 0.0002, Z = 1.21, P = .23) were related to changes in liver fat content. CONCLUSION HIIT elicits comparable improvements in liver fat to MICT despite often requiring less energy and time commitment. Further studies should be undertaken to assess the relative importance of aerobic exercise prescription variables, such as intensity, on liver fat.

Methodological quality

Publication Type : Comparative Study ; Meta-Analysis

Metadata

MeSH terms : Exercise Therapy ; Liver