Canadian scientists have published data that indicate exercise stimulates adult stem cells to form bone instead of fat. The scientists used a mouse model to study exercise effects on adult bone marrow stem cell and blood production. Using treadmill-conditioned mice, they found that aerobic exercise triggers adult stem cells to become bone more often than fat. The bone environment provides better conditions, called a "niche", for adult blood stem cell development. When the mice were sedentary, the stem cells tended to form fat, which impairs blood production in bone marrow cavities.

Dr. Gianni Parise, senior author on the study, said:

"The interesting thing was that a modest exercise program was able to significantly increase blood cells in the marrow and in circulation. What we're suggesting is that exercise is a potent stimulus -- enough of a stimulus to actually trigger a switch in these [adult] stem cells. Exercise has the ability to impact stem cell biology. It has the ability to influence how they differentiate."

The results were published online before print in The FASEB Journal.

Previous studies have shown that exercise can increase the number of muscle adult stem cells, the number of new brain neurons from adult stem cells, and the number of neural adult stem cells.