The Biology Behind Running’s Calming Effect

Running lifts us up and chills us out, two very different mental states that somehow result from the same activity. What’s up with that? Gretchen Reynolds, writing in the New York Times, directs our attention to research recently conducted at Princeton, where scientists studied two groups of mice, one that was allowed to run and one that was not. After six weeks, the running mice displayed more confidence than the sedentary mice. They were, for example, more willing to spend time in open areas. Reynolds reports that when the researchers examined the brains of the running mice, they found a large number of new brain cells that were specifically designed to release the neurotransmitter GABA, which inhibits brain activity, basically quieting the brain down in times of stress. The researchers then placed all the mice in a stressful environment, in this case cold water, and examined the biochemical response in their brains. All of the mice, unsurprisingly, responded with excitable cell firing in the brain, but the brains of the running mice, which released GABA, returned much more quickly to a state of calm. Read more in the New York Times.