Study sheds light on benefits of exercise

Exercise supports the treatment of non-alcoholic fatty liver disease by impacting several metabolic pathways in the body, according to a new study from the University of Eastern Finland. Regular HIIT exercise over a 12-week period significantly reduced the study participants’ fasting blood sugar and waist circumference, and improved their peak oxygen consumption rate and peak workload achieved. These positive effects were associated with changes in the abundance of a number of metabolites. In particular, exercise altered amino acid metabolism in adipose tissue. The study was published in Scientific reports.

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, affecting approximately 25% of the world’s population. Being largely asymptomatic, the disease can progress from fatty accumulation in liver cells to liver inflammation and liver cirrhosis. NAFLD is associated with obesity and other features of the metabolic syndrome, such as type 2 diabetes and abnormal blood lipid concentrations. The accumulation of fat in the liver can be reduced by weight loss and a healthy diet.

Exercise is an integral part of treating NAFLD. The benefits of exercise may be related not only to weight management, but also to alterations in body-produced metabolites and gut microbes, the role of which in fatty liver disease remains poorly understood.

Exercise alters metabolism even without trying to lose weight or change diet

In the new study, the researchers took a comprehensive look at the effects of exercise on metabolism in patients with non-alcoholic fatty liver disease. The randomized controlled intervention study involved 46 subjects diagnosed with NAFLD. They were divided into an exercise intervention group that had a HIIT (high-intensity interval training) session twice a week, plus an independent training session once a week for 12 weeks, and a group control who did not increase exercise during the study. None of the groups sought to lose weight or changed their eating habits during the intervention. In addition to conventional medical examinations and laboratory tests performed at the start and end of the study, researchers also performed untargeted metabolomic analyzes to identify various metabolites and their abundance in samples of adipose tissue, plasma, urine and stool. Based on the results, exercise affected metabolic pathways in different tissues differently.

Exercise had a beneficial effect on fasting glucose concentrations, waist circumference, maximal oxygen uptake rate, and maximal workload achieved. These factors were also associated with many of the alterations observed in the abundance of various metabolites in the exercise intervention group. The most significant alterations were observed in amino acids and their derivatives, lipids and bile acids.

In particular, exercise increased levels of amino acids, which are the building blocks of protein, in adipose tissue. According to the researchers, their higher accumulations in adipose tissue may be associated with improved lipid and glucose metabolism, as well as a reduction in insulin resistance.

Levels of various gut microbial metabolites were altered following exercise, suggesting changes in gut microbe composition or function. Among these metabolites, an increased amount of indolelactic acid, for example, can strengthen the intestinal mucosa, immune defenses and glycemic balance.

Based on the findings, exercise may have a beneficial effect on many disease-contributing factors in patients with NAFLD, even without weight loss or dietary changes. Adipose tissue appears to play a key role in these effects. Exercise improves fasting blood sugar and alters amino acid, lipid, and bile acid metabolism. However, abnormal blood lipid concentrations were not improved by exercise alone: ‚Äč‚Äčtheir treatment requires attention to the quality of dietary fat.

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