The Science Behind Running: What It Does to Your Mood


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As much as you may dread going on your morning runs, you do have to admit that post run your mood increases tremendously. Interestingly, a study conduced by the University of Montreal Research Centre explains exactly why a short run can turn your bad day into a good one and why your friend who runs marathons is always a little too happy to get in that extra mile.

The key to feeling rewarded by running is controlled by leptin, which is a hormone that plays an important role in the metabolism. 

According to Stephanie Fulton, a researcher at the University of Montreal and lead author of the study,  “Leptin inhibits physical activity through dopamine neurons in the brain.”

Interestingly enough, the link between the signals that modulate both exercise and hunger are believed to be closely related due to mammals evolving to become the most fit in order to find food sources. In other words, humans feel satisfied and happy after running because it is an activity that encourages the behavior of physical activity in exchange for food.

Although the research was not conduced on actual humans, the study found the link between dopamine and running by using mice. According to the study, while some of the mice remained normal, others went under genetic modification to suppress the molecule that is activated through leptin, called STAT3.


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First author of the study, Maria Fernanda Fernandes explains, “Mice that do not have the STAT3 molecule in the dopaminergic neurons run substantially more. Conversely, normal mice are less active because leptin then activates STAT3 in the dopamine neurons, signaling that energy reserves in the body are sufficient and that there is no need to get active and go looking for food.”

This shows how the leptin hormone along with the effect that the hormone has on the dopamine neurons plays a large role in why running can sometimes feel dreadful and other times provide a feeling of satisfaction commonly known as “runners high.”

Fulton also sums up the overall correlation between the study and its effects of humans and running in general. Fulton states, ”Previous studies have clearly shown a correlation between leptin and marathon run times. The lower leptin levels are, the better the performance. Our study on mice suggests that this molecule is also involved in the rewarding effects experienced when we do physical exercise. We speculate that for humans, low leptin levels increase motivation to exercise and make it easier to get a runner’s high.”

Ironically, the study shows that there is a correlation between eating and the joys of working out. The correlation dates back to the original idea of hunter gatherer. So next time you are running and feel unstoppable, remember that you have someone, somewhere way up your family tree, to thank for your ability to run and the happiness that follows after.

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