Studies shed light on how exercise can alter the expression of genes.
We all know exercise is good for us. It can melt away fat and help build muscle, ease depression, and has been shown to reduce the risk of cardiovascular disease, type 2 diabetes, and cancer. But how exactly does exercise work its magic? Evidence from several recent studies are shedding light on this mystery, showing how exercise can turn off and on genes within muscle and fat cells, altering metabolism and affecting disease risk.
Once thought to be unchangeable and the single determinant of what traits get passed on, it is now known that genes are greatly affected by the environment. Although the structure of the gene itself can’t be changed, lifestyle factors such as diet, stress, and exercise can change the expression of genes, turning them off or on. A gene that is silenced, or turned off, is unable to make the protein that will cause a certain effect in the body. A gene that is activated, or turned on, will make a protein when it receives the appropriate message from the body.
Methylation is one of the ways that genes are turned off or on. During methylation, a methyl group (structure made of carbon and hydrogen atoms) is added to the gene. Think of it as adding a cherry to the top of a sundae. The cherry (methyl group) will either block or assist the message from being received by the sundae (gene). Turning genes off and on affects all processes in the body, ultimately making an impact on behavior, mental processes, disease states, and physical appearance.
Exercise is one environmental factor that drives the process of methylation. In a recent study by researchers at Lund University Diabetes Center in Sweden, scientists set out to see exactly what exercise does to our genes. As part of their study, the scientists mapped expression of genes in fat cells before and after exercise in 23 men who worked out for one hour two times weekly for six months (1). Not only did exercising cause weight loss and improve cholesterol levels and blood pressure, but it also changed the methylation pattern at nearly 18,000 sites on 7,663 genes. Many of the modified genes were those involved in fat storage and obesity and diabetes risk.
Gene methylation isn’t limited to fat cells; exercise also affects methylation in muscle cells. In a study published in the journal Cell Metabolism last year, researchers collected muscle biopsies from 14 men and women both before and after exercise to determine the effect on gene methylation (2). Not only were major changes in the pattern of methylation seen after just one exercise session, but the researchers also found that more intense exercise caused even greater changes. Similar to what was seen in the fat cell study, several of the genes methylated in muscle cells following exercise are known to affect metabolism and the risk for obesity and diabetes.
It is often said that our genes and environment determine how we age and our risk for disease, suggesting that one factor (genes) is unchangeable, while the other (environment) we have control over. These new studies show how the environmental component of exercise is capable of influencing genes themselves, giving us an extra element of control. Exercise is an extremely powerful tool conferring loads of health benefits, likely driven largely by gene methylation. How exercise profoundly affects the body, even down to the level of DNA, is all the more reason for getting your daily dose of physical activity every day.
1. Rönn T, et al. A six months exercise intervention influences the genome-wide DNA methylation pattern in human adipose tissue. PLoS Genet. 2013 Jun;9(6):e1003572. doi: 10.1371/journal.pgen.1003572. Epub 2013 Jun 27.
2. Barrès R, et al. Acute exercise remodels promoter methylation in human skeletal muscle. Cell Metab. 2012 Mar 7;15(3):405-11. doi: 10.1016/j.cmet.2012.01.001.