Congcong He, PhD
Congcong He, PhD, research fellow, department of internal medicine, Center for Autophagy Research, University of Texas Southwestern Medical Center, Dallas.
If I asked you how exercise helps you stay fit and ward off all sorts of life-threatening diseases, you might point to the fact that movement burns calories and builds muscle, effects that are easily noticeable when your pants feel looser or your biceps bulge.
And that’s true, but a new study shows that those aren’t the only things that exercise does for you. There’s something else going on in a microscopic way at the cellular level that you probably don’t even realize is happening—exercise actually helps slough off damaged parts of cells.
When I learned more about the research, which is from University of Texas (UT) Southwestern Medical Center in Dallas, it reinforced just how amazing the human body truly is, and I think you’ll be wowed, too…
Before I jump into the exercise stuff, it will help to understand how your cells work (trust me—it’s interesting). Cells become damaged as you age, due to many factors that often are unavoidable, such as exposure to UV light, cigarette smoke and air pollution. And the more damaged they become, the higher your risk for all kinds of diseases and the harder it is to be fit and lose weight.
The good news is that there’s a mechanism in your body that turns on and off, and when it’s on, it rids the body of the damaged parts of cells. I explored this by talking to the coauthor of the study, Congcong He, PhD, a research fellow in the department of internal medicine at UT Southwestern.
The mechanism is called autophagy, meaning “self-eating,” and it’s like a cellular recycling process, Dr. He said. Once the damaged structures are destroyed, energy is extracted from the process and is used to build new, healthy cell structures. Nice, right? So Dr. He and her colleagues wanted to explore what triggers autophagy to turn on.
Dr. He said that research has shown that when the body is especially stressed, like when it is starved, that’s one known trigger. (Of course, starvation has down sides that outweigh any good.) But the researchers were curious to find out whether another source of “stress” could be a trigger—the fleeting stress that comes from moderate exercise.
For the study, which was published this past January in Nature, Dr. He’s team gathered 50 mice. Some of the mice were normal, but others had been bred so that their bodies wouldn’t be able to turn on autophagy from exercise (they were the control group). The mice ran on treadmills for 50 minutes daily for eight weeks. To see whether and when autophagy began, researchers “tagged” an autophagy-related protein in the mice with a substance that would glow green (noticeable under a microscope) if autophagy started.
And the result—autophagy did not kick in at all, as expected, in the mutant mice that had been bred that way. But in the normal mice, it kicked in, on average, after 30 minutes of exercise.
This news was intriguing to Dr. He because it shows that exercise is, in fact, a trigger of autophagy. In other words, besides burning calories and building muscle, just 30 minutes of moderate exercise appears to help renew the cells within your body, getting rid of the damaged ones and replacing them with new, healthy ones.
A second experiment done by Dr. He and her colleagues showed that the normal mice had greater endurance than the mutant mice. The normal mice could run for a little more than two hours, and the mutant mice could run for only an hour and a half. And a third experiment showed that the normal mice were able to use exercise to recover from disease. The team fed both mice groups a high-fat diet until they developed diabetes and high cholesterol. The normal group was able to reverse these conditions with exercise, but the mutant group was not.
The study was done only on mice, but Dr. He believes that the findings translate to humans because our bodies work in a similar way. In fact, Dr. said, “Triggering this cellular recycling process is likely a major reason that exercise helps humans boost endurance and ward off diseases.”
It’s fun to look in the mirror after you exercise to see how it makes you look better, but now, we also can think about what’s happening underneath our skin. It’s no wonder that exercise makes us feel so good—it’s dumping old cells and creating fresh cells inside of us!
