How exercise changes metabolism

A new study shows that a single workout can boost calorie burn by altering DNA.

For years research has been showing us that exercise does all kinds of good things for our bodies — from raising metabolism to protecting us from disease. Now that we know what a solid workout regime can do, laboratories of late have shifted their focus to zeroing in on how. The newest explanation: Exercise temporarily alters your DNA.

No, it’s not science fiction. A study published in the March 2012 issue of the journal Cell Metabolism confirmed a theory that a single bout of exercise expresses — i.e. “switches on” — genes responsible for energy metabolism. While DNA, your body’s inherited genetic instructional code, technically cannot be changed, environmental lifestyle factors like diet, exercise and stress play a large role in whether or not a gene is "turned on" and its function expressed.

In the study, the scientists took thigh-muscle biopsies of 14 healthy, non-exercising young men and women, average age 25, before and after each rode to exhaustion on an exercise bike (which didn’t take long). The lab analysis of the tissue samples detected a diminished presence of chemicals known as methyl groups, which are thought to limit the expression of genes that are specifically responsible for energy metabolism.

In other words, the genes that help you go faster and get stronger seemed to be awakened from their methyl-induced slumber by just one single bout of exercise; suddenly, like the Army, they were trying to be all that they could be. And the harder the subjects pushed themselves, the more bright-eyed and bushy-tailed the genes became.

When participants cycled at a high intensity (80 percent of their maximum aerobic capacity, researchers detected less methyl than when they rode at a low-intensity (40 percent of their maximum aerobic capacity), suggesting that muscle contraction stimulates the drop-off of these chemicals and the subsequent metabolic surge.

“It’s a big surprise,” says Geralyn Coopersmith, an exercise physiologist and national director of the Equinox Fitness Training Institute. “It shows that exercise is a more powerful drug than we thought. It’s more motivation to exercise every day.”

The bottom line? Your body is loaded with “good” genes and “bad” genes that often don’t do a thing until you stimulate them. This study, which identifies chemical methyl groups as a key gene expression agent, shows that exercise specifically targets genes related to metabolism, and concludes that intensity gives you more bang for your buck.

“We were born to exercise — it’s in our genes,” says Coopersmith. “75 to 80 percent of diseases are affected by diet, exercise, and other lifestyle choices. This study gives more fuel to the fire that we as a society need to change from hypokinetic (too little movement) to hyperkinetic (much more movement). Exercise is vital to us as a species.”