The Happiness of Running Explained by The Appetite
Why do we run? To be healthy, to take the air, to feel good … but also in prehistoric times to find food. According to Canadian research in Cell metabolism , the feeling of well-being that runners may feel is linked to dopamine, an important neurotransmitter for motivation.
In the course of evolution, the capacities of endurance racing mammals, especially those of humans, would have evolved to increase their chances of finding food. This is why the hormonal signals that control exercise and food intake could be related.
In this article, researchers studied mice that ran voluntarily in cages. These mice are able to run up to 7 km per day. The researchers compared the activity of normal mice to mice that had a genetic modification suppressing a leptin-activated molecule: STAT3.
Leptin is produced by adipose tissue and is involved in satiety control, but also influences physical activity. The STAT3 molecule is present in the neurons that make dopamine in the brain, a neurotransmitter involved in arousal, alertness and motivation.
As Maria Fernanda Fernandes, lead author of the study, explains, “Mice that do not possess the STAT3 molecule in dopaminergic neurons run much more. In contrast, normal mice are less active because leptin then activates STAT3 in dopaminergic neurons, indicating that the energy reserves in the body are sufficient and that there is no need to be active, Get food. “
Therefore, leptin is mediated by modulating physical activity, via dopaminergic neurons and acting on the reward system, as Stephanie Fulton, also author of the article, explains: “The more fat there is, the more There is leptin and less we want to eat. Our results now show that this hormone also plays an essential role in the motivation to run, which can be related to the search for food. “
Previous work had shown a link between leptin and marathon run times: the lower the leptin levels, the better the performance. Conclusion: Low leptin levels would motivate the individual to run. The message of the hormones sent to the brain is clear: when food is scarce, it is good to run to bring it back.
Maria Fernanda A. Fernandes, Dominique Matthys, Cécile Hryhorczuk, Sandeep Sharma, Shabana Mogra, Thierry Alquier, Stephanie Fulton, Leptin Suppresses the Rewarding Effects of Running via STAT3 Signaling in Dopamine Neurons, Cell Metabolism, Available online 1 September 2015, ISSN 1550-4131, http://dx.doi.org/10.1016/j.cmet.2015.08.003.