Yet, another huge benefit from exercising! From the NYTimes...
"Like muscles, many parts of the brain get a robust physiological workout during exercise. “The brain has to work hard to keep the muscles moving” and all of the bodily systems in sync, says J. Mark Davis, a professor of exercise science at the Arnold School of Public Health at the University of South Carolina and senior author of the new mouse study, which was published last month in The Journal of Applied Physiology. Scans have shown that metabolic activity in many parts of the brain surges during workouts, but it was unknown whether those active brain cells were actually adapting and changing.
To see, the South Carolina scientists exercised their mice for eight weeks. The sedentary control animals were housed in the same laboratory as the runners to ensure that, except for the treadmill sessions, the two groups shared the same environment and routine.
At the end of the two months, the researchers had both groups complete a run to exhaustion on the treadmill. Not surprisingly, the running mice displayed much greater endurance than the loungers. They lasted on the treadmills for an average of 126 minutes, versus 74 minutes for the unexercised animals.
More interesting, though, was what was happening inside their brain cells. When the scientists examined tissue samples from different portions of the exercised animals’ brains, they found markers of upwelling mitochondrial development in all of the tissues. Some parts of their brains showed more activity than others, but in each of the samples, the brain cells held newborn mitochondria.
There was no comparable activity in brain cells from the sedentary mice."