Why To Exercise Today: It's Your Body's Housecleaning

Autophagy! That's the scientific term that will come to my mind from now on when I'm done working out and feel like the sweat and heavy breathing have just magically accomplished a cathartic full-body detox. "Auto" refers to self, "phagy" refers to eating, and the whole term means a cell's self-cleaning process — biological housework, so to speak.

As Gretchen Reynolds explains today in her excellent New York Times Phys Ed column, that lovely feeling of flushing out junk mirrors action at the cellular level. (Not that there are any findings on whether the feeling and the biology are actually connected, of course, but don't you think?)

She writes about an experiment in mice to see whether the healthful effects of exercise might be connected to autophagy. The researchers compared a strain of mice whose autophagy did not increase in response to stress. (Exercise is considered stress.) Sure enough, in them, exercise did not fight Type 2 diabetes as it did in others:

More striking, when Dr. Levine stuffed both groups of animals with high-fat kibble for several weeks until they developed a rodent version of diabetes, the normal mice subsequently reversed the condition by running, even as they continued on the fatty diet. The autophagy-resistant animals did not. After weeks of running, they remained diabetic. Their cells could not absorb blood sugar normally. They also had higher levels of cholesterol in their blood than the other mice. Exercise had not made them healthier.

In other words, Dr. Levine and her colleagues concluded, an increase in autophagy, prompted by exercise, seems to be a critical step in achieving the health benefits of exercise.