What makes one person a gym junkie and the other a couch potato might come down to science.
New evidence published in The Journal of Physiology speculates that genetics may affect how much you enjoy exercise. [Tweet this news!] This could explain why it's harder to motivate some people to lace up and break a sweat even if they know how important it is to their health and well-being.
Researchers at the University of Missouri studied how genes may play a role in the desire—or lack thereof—to work out by inter-breeding very active lab rats (those who voluntarily ran on wheels) with each other to make an avid-exercising group. Then they paired up sedentary rats to make an anti-exercising group. They continued to mate rats in these two groups for generations, and learned that a portion of the brain called the nucleus accumbens, which is associated with reward processing, lit up for the active group but not for the inactive group whenever they were placed on the wheel. In other words, those who came from a family of runners were more likely to enjoy running, whereas those who came from a lazier line were least likely to have fun or keep at it.
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Thankfully the experiment didn't end on that dismal note: Researchers then decided to try to change the reluctant runners' habits by placing them on the wheels anyway and making them run a total of two miles over the course of six days. In that short period, results show that their brain activity began to change, and while they were still less inclined to exercise than their fitter counterparts, they were starting to reap more neurological rewards from it than before.
What does this mean for you? Further tests involving human subjects are still needed before researchers can say that this is true for us too. But the hope is, even if you are predisposed to dislike exercise, you still have a chance to train yourself to like it despite your DNA.
“People can decide to exercise,” study author and professor of biomedical sciences at the University of Missouri Frank Booth told The New York Times. Your fitness fate is still in your hands.