Effect of exercise training on liver function in adults who are overweight or exhibit fatty liver disease: a systematic review and meta-analysis.
OBJECTIVE
Exercise training has been shown to have beneficial effects on liver function in adults overweight or with fatty liver disease. To establish which exercise programme characteristics were likely to elicit optimal improvements.


METHODS
Systematic review and meta-analysis of randomised, controlled trials.


METHODS
PubMed, CINAHL and Cochrane controlled trials registry searched (1966 to 2 October 2015).


METHODS
Exercise intervention, with or without dietary intervention, versus usual care in adults undertaking, exercise training, who were overweight, obese or exhibited fatty liver disease (non-alcoholic fatty liver disease or non-alcoholic steatohepatitis).


RESULTS
We included 21 randomised controlled trials, totalling 1530 participants. Exercise intervention studies with total exercise programme workload >10 000 kcal produced significant improvements in intrahepatic fat, -3.46% (95% CI -5.20% to -1.73%), p<0.0001, I2=73%; effect size (standardised mean difference, SMD) -1.77 (-3.11 to -0.42), p=0.01, I2=77%. When data from only exercise studies were pooled, there was a reduction in fasting free fatty acids (FFAs) -74.15 µmol/L (95% CI -118.47 to -29.84), p=0.001, I2=67% with a large effect size (SMD) -0.94 (-1.36 to -0.52), p<0.0001, I2=0%. When data from only exercise studies were pooled, there was a significant reduction in insulin MD -1.88 UL (95% CI -3.43 to -0.34), p=0.02, I2=31%. The liver enzymes, alanine aminotransferase, aspartate aminotransferase and γ-glutamyl transpeptidase, were not significantly altered with exercise.


CONCLUSIONS
Exercise training reduces intrahepatic fat and FFAs while increasing cardiorespiratory fitness. An aggregate exercise programme energy expenditure (>10 000 kcal) may be required to promote reductions in intrahepatic fat.
School of Science and Technology, University of New England, Armidale, New South Wales, Australia.
N A
NA
Smart
School of Biomedical and Healthcare Sciences, Plymouth University, Plymouth, UK.
N
N
King
School of Science and Technology, University of New England, Armidale, New South Wales, Australia.
J R
JR
McFarlane
Department of Statistics, Macquarie University, Sydney, New South Wales, Australia.
P L
PL
Graham
School of Science and Technology, University of New England, Armidale, New South Wales, Australia.
G
G
Dieberg
D050154:Adiposity; D005081:Exercise Therapy; D005227:Fatty Acids / Q000097:blood; D006801:Humans; D008099:Liver / Q000201:enzymology / Q000502:physiology*; D065626:Non-alcoholic Fatty Liver Disease / Q000628:therapy*; D050177:Overweight / Q000628:therapy*; D016032:Randomized Controlled Trials as Topic
D005227:Fatty Acids
Evidence based review; Liver; Meta-analysis; Prevention