Exercise reduces inflammation and oxidative stress in obesity-related liver diseases

Weight reduction remains the most common therapy advocated for the treatment of obesity-related liver diseases. Recently, a beneficial effect of exercise regimens for liver dysfunction, independent of weight reduction, has been reported. Therefore, a retrospective analysis was conducted to determine whether exercise training without dietary restriction in obese, middle-age men influences the pathophysiology of abnormal liver function.

A total of 108 subjects who completed a 12-wk exercise training program without any dietary restriction were analyzed in this study; these results were compared with those of 104 subjects who completed a 12-wk dietary restriction program. Furthermore, 42 of these subjects (from both groups) who had abnormal liver function and suspicious liver fibrosis by nonalcoholic fatty liver disease fibrosis score were analyzed to obtain a more concrete outcome for exercise-training effects.

In exercise training, although the magnitude of body-weight reduction (-3.1% vs -8.5%), waist circumference (-4.0% vs -7.1%), and visceral adipose tissue area (-12.2% vs -22.5%) was significantly more modest than that achieved by dietary restriction, exercise training elicited equivalent reductions in serum alanine aminotransferase and gamma glutamyl transpeptidase levels (-20.6% vs -16.1% and -25.7% vs -34.0%) and equivalent improvement of insulin resistance (-29.7% vs -26.9%). Moreover, exercise training remarkably increased the serum adiponectin level (+33.4% vs +15.1%). Importantly, for subjects with abnormal liver function and suspicious liver fibrosis, exercise training was effective in reducing the serum levels of inflammation and oxidative stress markers: ferritin and thiobarbituric acid reactive substances (-25.0% vs +1.1% and -33.5% vs -10.5%).

Exercise training benefits the management of obesity-related liver diseases independent of detectable weight reduction. Particularly, these effects seem to be acquired through an improvement in the hepatic inflammatory condition and its related oxidative stress levels.