I’m a runner, but I never realized how much of a couch potato I was when I wasn’t running–until Fitbit. And since fitness contributes to both physical and mental health, you have good reason to lace up those sneakers. From How the Body Knows Its Mind.
I wear a Fitbit on my left wrist day and night, while washing dishes and even in the shower. In fact the only time I take it off is when I get an email message warning me the battery is low. And then I remove it reluctantly, preferably before I go to sleep and am not likely to be walking around. Fitbit is a fitness tracker I wear as a wristband that tracks my steps and the minutes throughout the day when I am active. My friend Melissa turned me on to it after she got one as a way to make sure she was keeping active during her pregnancy. We could compete against each other, she said. The one who takes the most steps a day wins. Never one to turn away from a little competition, I jumped at the chance, not only to try to show up my friend but because I was in the middle of teaching a class on neuroscience and education at the University of Chicago and we had just finished reading several new research papers on the power of exercise in changing the brain. If tracking my activity with the Fitbit motivated me to take more steps throughout the day, then why not try it? It seemed like a good idea to practice what I was teaching.
I am a runner and make sure to get in several runs a week, but before I had the Fitbit I never realized how much of a couch potato I was when I wasn’t lacing up my sneakers. The device made me mindful that the little things I did could add up to a significant amount of mileage a day. Just parking my car at the far end of the parking lot when I made a trip to the grocery store or taking the stairs rather than the elevator to my office on the third floor of the psychology building made the difference between getting in eight thousand steps a day and exceeding my goal of ten thousand.
The Fitbit is also a fun conversation starter. Because wearing the gadget signals that you are buying into the power of movement, it’s easy to strike up a conversation with strangers at restaurants and on the train who are wearing a similar device. Of course, most of the conversations I find myself engaged in with fellow Fitbitters have to do with how important exercise is for maintaining a healthy body. It’s rare that folks think about exercise in terms of benefiting the mind. Yet fitness contributes to both physical and mental health. Brains look and function differently according to whether they are housed in inactive or active bodies.
Exercise simulates the creation of new brain cells, a process known as neurogenesis. Some of the first research documenting the link between physical activity and the brain was done using mice. Mice raised in “enriched environments,” in which they had toys, exercise wheels, and lots of opportunities for social interaction, grew more new brain cells than their litter mates housed in standard laboratory cages. Scientists weren’t actually sure which part of the mice’s surroundings caused the new cell growth, so, in the late 1990s, researchers at the Salk Institute at the University of California, San Diego, conducted studies to find out. They systematically examined the different parts of the mice’s environment in order to unveil what exactly was responsible for the neurogenesis.
The experiment that conclusively demonstrated the striking power of exercise on brain function followed a simple protocol. The scientists began by giving all of their young mice a chemical that could track the brain cells when they divided and new cells were produced. They then offered some mice access to “exercise equipment”—a running wheel that they could use as often as they liked. Another group of mice didn’t have the opportunity to exercise and led a fairly inactive lifestyle. After several weeks, the scientists sacrificed the rodents so they could see if and how the brains of the two groups differed. They found striking differences: those mice that had been on the move had more new brain cells, roughly twice as many, compared to their sedentary counterparts.
To make sure it was the vigorous exercise that had changed the mice’s brains, the Salk researchers enrolled another group of mice in their study. The mice in this new group learned how to navigate a maze. They had a lot of mental exertion but not as much physical activity as their wheel-running counterparts. Surprisingly, the opportunity to expend cognitive effort didn’t lead to nearly as much proliferation of new brain cells as running did. The lesson here? Even though we are often tired after a long day of work and it feels as though we have run a marathon, it’s not the same as actually hitting the track—at least to our brains. Vigorous exercise is important for growing new brain cells.