Increased cellular cleaning from exercise produces health benefits

Source: Nature, The New York Times; February 2012

University of Texas Southwestern scientists recently conducted a study regarding the accumulation of flotsam, the “trash heap” that naturally occurs inside cells. This flotsam, composed of misshapen or broken proteins and shreds of cellular membranes (among other material), is the result of everyday wear and tear in the body. 

Cells in the body usually sweep away this debris and in a process called autophagy (“self-eating”), cells recycle this flotsam for energy. If they don’t, the cells become cluttered with the trash and malfunction or die, something doctors have recently suspected is linked to many diseases, including diabetes, muscular dystrophy, Alzheimer’s and cancer. The slowing of this process is also thought to be linked to aging.

The U.T. researchers used mice to study the role of exercise on autophagy. They found that after 30 minutes of running, the mice experienced “accelerated autophagy.” In order to determine how this affected the mice’s overall well-being, researchers developed a new strain of mouse that experienced stable autophagy levels regardless of diet and exercise changes.

They found that when compared to normal mice, these mice, incapable of experiencing accelerated autophagy, quickly grew more fatigued during exercise than the normal mice, had muscles incapable of drawing sugar from the blood, and were unable to reverse a rodent version of diabetes because their cells could not absorb blood sugar normally. They also had higher levels of cholesterol. In sum, exercise did not make them healthier. 

The researchers conclude that an increase of autophagy prompted by exercise is a crucial part of achieving the health benefits of exercise, underscoring the importance of staying active.