We all know that exercise promotes health and reduces the risk of developing diabetes, obesity, heart disease, and stroke, and other diseases. But how, at a cellular level, does it do it? Several new studies provide some insight by showing that exercise seems to alter how genes operate. Certain genes are static; the color of your eyes and hair, how tall you are, etc., are examples of genes you have no control over. But many other genes are not static; they can be turned on or off, depending on what signals they receive from elsewhere in the body. When they are turned on, genes prompt a range of physiological actions in the body. One powerful way of affecting gene activity is a process called methylation ( a methyl group contains carbon and hydrogen atoms), in which methyl groups attach to the outside of a gene and either up or down-regulate that gene. What makes the methylation process so interesting is that it seems largely driven by lifestyle choices. Diet, for example, profoundly affects the methylation process, and researchers suspect that differing methylation patterns resulting from different diets may be partly responsible for determining who develops diabetes and who does not. But the role of physical activity in gene methylation has been poorly understood, even though exercise, like diet, has profound effects on the body. Recently, several groups of scientists set out to determine what working out does to our genes, and it turns out to be a lot. In a study at the Lund University Diabetes Centre in Sweden and published last month in PLoS One, researchers took several dozen sedentary but generally healthy Swedish men and sucked out some fat cells so they could map the existing methylation patterns on the DNA within those cells. They also measured the men’s body composition, aerobic capacity, waist circumference, blood pressure, cholesterol levels, and other fitness markers. They then asked the men to work out twice a week, an hour each session for six months, under the guidance of a trainer. By the end of that time, the men had shed fat around their waists, increased their endurance, and improved their blood pressure and cholesterol levels. They also altered the methylation pattern of many of the genes in their fat cells. The genes showing the greatest methylation also tended to be those that played a role in fat storage and the risk for developing diabetes and obesity! Another study, published in Cell Metabolism (March, 2012) found a dose-dependent exercise-induced gene methylation in skeletal muscle, corroborating the later study. More reasons that exercise is good for you. Bottom line If you want to increase your chances of good health, you need to exercise! For a more thorough coverage on the issue, read my favorite fitness writer Gretchen Reynolds’ article in the New York Times (7/31/13).

Stay well, John R Blilie, M.S.