Smiling could boost athletic performance, a new study claims.
Researchers found grinning can reduce an athlete's perceived effort, or how hard they feel they are working, making the sport easier for them, The Daily Mail reports.
In fact, researchers say many top athletes, including Olympic marathon gold medalist Eliud Kipchoge, smile to enhance their performance.
The findings, published in the Psychology of Sports and Exercise, suggest smiling helps reduce muscle tension and distract runners from bodily sensations, thus making running easier.
"I had noticed some athletes use smiling during running and cycling events, and I was curious to know whether this strategy actually had any measurable impact on endurance activity," researcher Noel Brick said.
Brick and his colleagues at Ulster University in Northern Ireland asked 24 trained runners to complete four six-minute running blocks on the treadmill, with a two-minute rest between each block.
The runners completed the blocks while smiling, frowning, while consciously relaxing their hands and upper-body, or with a normal attention focus.
After each run, they reported on how they felt while running.
The subjects also wore a breathing mask so researchers could measure how much energy they used while running.
Researchers found participants used 2.8 percent less energy when smiling compared to frowning.
They also found runners conserved 2.2 percent more energy in comparison to normal attention focus.