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Trickle down effect of exercise

New study finds that exercising changes the functioning of genes that affect how healthy and fit our muscles become
We all know that exercise can make us fitter and reduce our risk for illnesses such as diabetes and heart disease. But just how, from start to finish, a run or a bike ride might translate into a healthier life has remained baffling.
Now new research reports that the answer may lie, in part, in our DNA. Exercise, a new study finds, changes the shape and functioning of our genes, an important stop on the way to improved health and fitness.
The human genome is astonishingly complex and dynamic, with genes constantly turning on or off, depending on what biochemical signals they receive from the body. When genes are turned on, they express proteins that prompt physiological responses elsewhere in the body. Scientists know that certain genes become active or quieter as a result of exercise. But they hadn’t understood how those genes know how to respond to exercise.
Enter epigenetics, a process by which the operation of genes is changed, but not the DNA itself. Epigenetic changes occur on the outside of the gene, mainly through a process called methylation. In methylation, clusters of atoms, called methyl groups, attach to the outside of a gene like microscopic mollusks and make the gene more or less able to receive and respond to biochemical signals from the body.
Scientists know that methylation patterns change in response to lifestyle. Eating certain diets or being exposed to pollutants, for instance, can change methylation patterns on some of the genes in our DNA and affect what proteins those genes express. Depending on which genes are involved, it may also affect our health and risk for disease.
Most of the genes in question are known to play a role in energy metabolism, insulin response and inflammation within muscles. In other words, they affect how healthy and fit our muscles — and bodies — become. They were not changed in the unexercised leg.
Many mysteries still remain, though, said Malene Lindholm, a graduate student at the Karolinska Institute, who led the study. It’s unknown, for example, whether the genetic changes she and her colleagues observed would linger if someone quits exercising and how different amounts or different types of exercise might affect methylation patterns and gene expression.