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New Study: Exercise is our Cells' Trash Collection Service

By Kellee Bryan
A new study shows that physical activity triggers an increased rate of "garbage" removal at a cellular level, and that this trash collection is a crucial mechanism for maintaining and improving health. The study was conducted by scientists at the University of Texas Southwestern Medical Center in Dallas, and published in Nature.

Garbage day
Photo by Kevin Dooley

Much like my dining room table, our cells collect life's detritus throughout the day and must be consistently cleared of clutter in order to perform their intended functions properly. For our cells, this involves a process called autophagy, or "self-eating," in which cellular debris (like broken proteins, bits of membranes, aged mitochondria, or vanquished bacteria) is turned into figurative food pellets and "eaten" for fuel.

Without regular house cleaning, cells become clogged with trash and malfunction or even die. And some scientists suspect that it may be this rubbish build-up that leads to the development of a number of diseases, such as diabetes, cancer, and Alzheimer's.

Scientists have long known that when cells are under stress, autophagy increases. Calorie restriction, for example, can "starve" a cell and trigger the autophagy response. This study's researchers wondered if exercise – another form of physiological stress – would also increases autophagy and, if so, what effects it has on the body's overall health.

They tested mice before and after 30 minutes of exercise and found that, in fact, the mice did show increased autophagy after their work outs. In order to determine what effect the exercise-induced acceleration had on the health and well being of the mice, the researchers compared "normal" mice to lab-developed autophagy-resistant mice (mice incapable of increased autophagy, regardless of absence or presence of a physiological stressor).

What they found was that exercise fatigued the autophagy-resistant mice more quickly than their normal counterparts. Their muscles appeared to be incapable of pulling sugar from their blood. Further, diabetic mice with a normal autophagy response were able to reverse their disease by exercising - even when they continued to be fed the poor diet that had led them to become diabetic in the first place. Conversely, autophagy-resistant diabetic mice remained diabetic even with exercise.

The conclusion drawn by the researchers is that exercise triggers an increase in cellular autophagy, without which the benefits normally attributed to exercise alone would not be realized. The study's authors speculate that these findings could have implications for diabetes research and treatment, or lead to the development of autophagy-boosting specialized exercise programs and pharmaceuticals.

Posted on February 8, 2012 10:14 PM