Although endorphins previously garnered all of the credit for the rewarding and euphoric sensation related to running, a recently published study by researchers at the University of Montreal reveals dopamine as a new factor in the discussion.
Running continues to become increasingly popular in the United States, especially endurance running in the form of marathon distances and beyond. Have you ever wondered if there is a common factor motivating so many to cover such long distances? Why do some runners describe a sense of euphoria, or “high,” during a run, while it remains absent in others? Forrest Gump, famously quipped that he “just felt like running” as he embarked on his coast to coast trek in the 1994 film. Is there a deeper motivation?
Although running is a common way to maintain fitness in today’s society, allowing for one to enjoy the occasional over-indulgence, our ancestors may have engaged in endurance activity for other reasons – to actually acquire food. Though food acquisition now can be as simple as a trip to the supermarket, the evolutionary by-product of engaging in endurance activity to obtain food may still remain as a motivator for your daily run.
“We discovered that the rewarding effects of endurance activity are modulated by leptin, a key hormone in metabolism. Leptin inhibits physical activity through dopamine neurons in the brain,” said Stephanie Fulton, researcher at University of Montreal Hospital Research Centre and lead author of the published study.
Dopamine, a neurotransmitter found in humans, is largely responsible for feelings of reward, pleasure, and motivation. Because of the link to both dopamine and metabolism in the study, researchers believe humans may have a hardwired motivation toward endurance activity for food acquisition. Leptin, which is known to help control feelings of hunger, also influences physical activity.
Within the study, the activity of voluntary wheel running was measured in two groups of mice. Normal mice served as the control group, while a second group of mice were modified in such a way that simulated lower leptin levels. By comparison, the mice in the genetically modified group exhibited higher levels of activity (measured by wheel running).
“Our findings now show that [leptin] also plays a vital role in motivation to run, which may be related to searching for food,” explained Stephanie Fulton.
Though the concept isn’t necessarily brand new, the idea that running has a biological link to our ancestors may be gaining momentum. In the last half decade alone, the best-selling book “Born to Run,” and the subsequently inspired documentary Fair Chase both provide arguments that human motivation and proclivity for endurance activity may have a more evolution-based, biological link to food acquisition behavior.
So what does the recent study on mice teach us with regard to human motivation for running? How does this relate to running performance in humans? Why the variance in experiences with a runner’s high? To a degree, it all depends on the individual.
According to Fulton, multiple studies have already demonstrated a correlation between leptin and marathon performance. “The lower leptin levels are, the better the performance. We speculate that for humans, low leptin levels increase motivation to exercise and make it easier to get a runner’s high.”
As a human race, we have been running for many years. In the modern era, for both extrinsic (physical appearance, raising money, earning a medal) and intrinsic (accepting a challenge, meeting a goal) reasons. However, the notion for a third type of motivation, a biological one, is steadily gaining support through ethnographic research and lab experiments such as these. Although you likely do not have to spend hours or days seeking out and acquiring your food, your body may still be hardwired to make that association, and get you on the move.
Featured photo credit: Forrest Gump Point, Monument Valley, Utah/Fabio Achilli via flickr.com
