How Exercise Changes Our DNA

How Exercise Changes Our DNA
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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.
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.
.So for a study published this month in Epigenetics, scientists at the Karolinska Institute in Stockholm recruited 23 young and healthy men and women, brought them to the lab for a series of physical performance and medical tests, including a muscle biopsy, and then asked them to exercise half of their lower bodies for three months.
One of the obstacles in the past to precisely studying epigenetic changes has been that so many aspects of our lives affect our methylation patterns, making it difficult to isolate the effects of exercise from those of diet or other behaviors.
The Karolinska scientists overturned that obstacle by the simple expedient of having their volunteers bicycle using only one leg, leaving the other unexercised. In effect, each person became his or her own control group. Both legs would undergo methylation patterns influenced by his or her entire life; but only the pedaling leg would show changes related to exercise.
The volunteers pedaled one-legged at a moderate pace for 45 minutes, four times per week for three months. Then the scientists repeated the muscle biopsies and other tests with each volunteer.
Not surprisingly, the volunteers’ exercised leg was more powerful now than the other, showing that the exercise had resulted in physical improvements.
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.
The upshot is that scientists now better understand one more step in the complicated, multifaceted processes that make exercise so good for us.
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. She and her colleagues hope to examine those questions in future studies.
But the message of this study is unambiguous. “Through endurance training — a lifestyle change that is easily available for most people and doesn’t cost much money,” Ms. Lindholm said, “we can induce changes that affect how we use our genes and, through that, get healthier and more functional muscles that ultimately improve our quality of life.” more