Being Sedentary Changes the Brain (And Not for the Better)

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Carrie Steckl earned her Ph.D. in Counseling Psychology with a Minor in Gerontology from Indiana University – Bloomington in 2001. She has spent over ...Read More

We’ve been told time and again to get off the couch because being sedentary isn’t good for us. But why is it so bad for us? We know that people who live sedentary lifestyles are more likely to develop a host of conditions like heart disease, diabetes, and cancer. Yet, we’re not given much information about why this happens.

Thanks to researchers at Wayne State University School of Medicine and other institutions, we now have a clearer answer to this question. In an article recently published in the Journal of Comparative Neurology, the researchers described what happened in the brains of rats when they spent their time actively or inactively.


But before I tell you about the results, let’s have a mini-class on the brain. The brain is made up of neurons, which are sometimes also called brain cells or nerve cells. As recently as 20 years ago, we thought that upon reaching adulthood, neurons could not be generated or altered (unless we killed them off entirely by drinking alcohol, that is).

Now we know that this isn’t true. The brain actually has the capacity to generate new neurons well into old age. It also has the ability to alter and repair damaged neurons such as those impaired by chronic alcohol use (no, alcohol doesn’t actually kill off brain cells). Now that’s good news! But how activity or inactivity affected neurons was still a mystery.

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For this study, researchers focused on a part of the brain called the rostral ventrolateral medulla, which controls our sympathetic nervous system. In plain English, the researchers studied a part of the brain that affects blood vessel activity, blood pressure, and related risks for heart disease. Imaging of human brains suggests that like rats, we also have this part of the brain and that it functions similarly.

Two groups of rats were followed: a group with exercise wheels in the cage and a group with no exercise wheel. Rats love to run (Don’t you wish we had this tendency?), so they naturally ran their little tails off for the next three months. The other poor rats? They sat on their tushes the entire time. When the three months were up, the researchers looked at the neurons in the rostral ventrolateral medulla.

Now here’s where it gets interesting. The brains of the active rats looked – well – just the same as before the study. Their neurons were functioning well and nothing had really changed. But the sedentary rats? Their neurons had sprouted a bunch of additional branches, which are kind of like tentacles that help neurons communicate with each other. This sounds like a plus, but there can actually be too much of a good thing when it comes to these branches in this part of the brain. Since we’re talking about being a couch potato, think of these branches like the eyes that sprout on a potato when it sits in your pantry for too long.

Unnecessary neuron branches in this part of the brain create an overactive sympathetic nervous system, which can lead to high blood pressure and related problems that cause heart disease. Voila! This may be why being sedentary is so bad for us. Who would have thought that sitting on our butts might cause our brains to grow things we don’t need? But that’s what this research is suggesting. While this study involved rats and not humans, the generalizability of the findings is strongly supported.

So…what are you going to do to be active today?


Reynolds, G. (January 22, 2014). How inactivity changes the brain. The New York Times. Permalink:

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