Can Smiling While Exercising Improve Performance?

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Many athletes have been told that smiling while sweating will make our efforts feel easier. In May, Eliud Kipchoge, the Kenyan marathon runner, periodically grinned through the final miles of his fastest-ever marathon, which he completed in 2 hours 25 seconds; afterward, he said that he had hoped that the smiling would ease him to the finish line. But there has been little solid scientific evidence to support this idea. Several past studies have examined whether deliberately smiling can alter how people feel psychologically during races, but few have looked at the physiological impact on sports performance.

For a new study published in September in Psychology of Sport and Exercise, researchers from Ulster University in Northern Ireland and Swansea University in Wales decided to gather a group of experienced recreational runners and have them alternately grin and grimace as they ran. The 24 volunteers, men and women, were not aware of the study’s purpose: They were told that the experiment would look at a variety of factors related to “running economy,” a measure of how much oxygen you use to stride at a given speed.

First, the researchers tested the volunteers’ usual running economy by having them don a facial mask to measure their respiration and then run on a treadmill until they were exhausted. As they ran, the scientists asked them to rate how they felt and describe what strategies they were using to keep going, such as ignoring their bodies’ discomfort or tuning in to it.

Then, on a separate lab visit, each volunteer completed a series of four six-minute runs, during which they were assigned four approaches: to smile continuously but sincerely, to frown, to relax their upper body by imagining they gently held a potato chip between loose fingers or, as a control, to use their normal get-me-through-this-run mental techniques.

There were variations in the results. A few runners were most economical when they frowned; the researchers speculate that their grimaces, like ferocious “game faces,” increased their determination to outdo their normal performance. But the runners turned out to be most economical when they smiled. As a group, their economy then was as much as 2.78 percent more efficient than during the other runs, a meaningful difference in competitions. Smiling probably aided economy by prompting a “reduction in muscular tension,” says Noel Brick, a lecturer in sport and exercise psychology at Ulster University, who led the study.

Many of the runners found it difficult to smile throughout the six-minute session, though: Their grins became increasingly fixed and unnatural. Such false smiles activate fewer facial muscles than the sincere version, Brick said, and most likely result in less relaxation and performance enhancements. So the key to using a happy smile to make you a better runner, he says, may be to grin sincerely and often near a race’s end, but in 30-second bursts, rather than continuously. “This is what Eliud Kipchoge seems to do,” Brick said.