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No difference between moderate and vigorous exercise for patients with NAFLD

For patients with nonalcoholic fatty liver disease, no difference was found between moderate and vigorous exercise in reducing liver fat, according to recent findings published in JAMA Internal Medicine.

“Nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions worldwide and is the most common cause of chronic liver disease,” Hui-Jie Zhang, MD, PhD, study co-author and postdoctoral research fellow in the department of epidemiology at Tulane University School of Public Health and Tropical Medicine, and colleagues wrote. “This study indicated that vigorous exercise at 65% to 80% of the maximum heart rate and moderate exercise at 45% to 55% of the maximum heart rate for 150 minutes per week are equally effective in reducing the [intrahepatic triglyceride (IHTG)] content among patients with central obesity and NAFLD.”

In 2011, a retrospective clinical trial suggested that vigorous but not moderate exercise was associated with a lower risk for NAFLD, however this study did not provide dose-response information.

To verify this finding, Zhang and colleagues performed a randomized clinical trial of 220 patients (mean age, 53.9 years; 67.7% women) with central obesity and NAFLD in China between 2011 and 2013. Participants were assigned to three groups. The vigorous exercise group (n = 73) was instructed to jog for 150 minutes per week at 65% to 80% of maximum heart rate for 6 months and then to power walk for 150 minutes per week at 45% to 55% of maximum heart rate for another 6 months. The moderate exercise group (n = 73) was instructed to power walk for 150 minutes per week for 12 months, and the control group (n = 74) was instructed to perform no exercise for 12 months. At 6 and 12 months, the researchers used proton magnetic resonance spectroscopy to measure IHTG content. In addition, they recorded changes in body weight, waist circumference, body fat and metabolic risk factors.

Compared with the control group at the 6-month assessment, IHTG content was reduced by 5% (95% CI, –7.2% to 2.8%) in the vigorous group and by 4.2% (95% CI, –6.3% to –2%) in the moderate group. At the 12-month assessment, it was reduced by 3.9% (95% CI, –6% to –1.7%) in the vigorous group and by 3.5% (95% CI, –5.6% to –1.3%) in the moderate group. After adjusting for weight loss, most of the differences between the two groups became nonsignificant. Although both groups reduced body weight, waist circumference and blood pressure, only the vigorous exercise group was able to reduce body fat.

This study supports the current physical activity guidelines for the management of NAFLD that recommend 150 minutes of moderate intensity exercise per week, the researchers wrote.

“Because moderate exercise is more sustainable and provides most of the benefit of vigorous exercise, it should be recommended for the prevention and treatment of NAFLD,” the researchers wrote. “These findings indicate that the effect of the exercise intervention on the IHTG content reduction was most likely mediated by weight loss.”

Disclosure: The researchers report no relevant financial disclosures.