Faces Of Pain: Smile To Run Better

Research shows the painful faces we make when running are far from arbitrary.

Research shows the painful faces we make when running are far from arbitrary.

Many years ago I was running intervals at the track when I noticed something. I believe I was somewhere around the third lap of my fourth 1,600-meter interval in a set of six when I became aware that my entire face was tense. By this point in the workout I was feeling rather fatigued and working very hard. My facial muscles were contracting as part of the overall effort. Nothing unusual about that, but on this particular occasion I became conscious of it and responded by consciously relaxing my muscles, which I was able to do quite easily because, of course, it is not necessary to tense one’s facial muscles to run hard. When I relaxed my face I felt that the effort required to complete the interval was ever so slightly reduced.

You can tell how hard any runner is working simply by looking at his or her face. The greater the effort, the more agonized the facial expression becomes. In the last part of any race, runners typically wear facial expressions that, outside of the running context, are seen on them only when they are in pain. The last-mile-of-a-marathon look is also the post-toe-stub look.

This phenomenon is so normal as to be almost invisible—so common that few runners ever think to question its cause or purpose. But Samuele Marcora has made a career of questioning things that others do not. A few years ago, the Bangor University (Wales) exercise physiologist coauthored a paper entitled, “The face of effort: Frowning muscle activity reflects effort during a physical task.” Marcora is an expert on perception of effort, which is basically the phenomenon of how hard exercise feels. He believes that exercise performance is regulated by perception of effort and that it is the sole cause of fatigue. In other words, he believes we bonk because we give up, and we give up because we can’t stand the suffering any longer.

RELATED: How Pain Tolerance Affects Running Performance

The thing about perception of effort is that it’s subjective. It’s tricky to study because it’s difficult to measure. One must ask an exerciser to rate his or her effort on some sort of scale and trust that the answer is reliable. And it’s a known fact that the answer is not always reliable. In his paper, coauthored with Helma de Morree, Marcora notes that, for example, male exercisers tend to rate their perception of effort lower when a female researcher asks them to rate it. (Ah, men: so predictable!) Given the unreliability of self-ratings of effort, wouldn’t it be nice if there were some objective indicator of this subjective phenomenon that scientists could simply measure?

Marcora hypothesized that frowning just might be such an indicator. So he tested the idea by placing EMG sensors on the faces of subjects while they exercised. These sensors measured the amount of electrical activity in the frowning muscles of the face while subjects performed leg extensions at different workloads and either with or without pre-fatiguing exercise performed beforehand. EMG sensors were also placed on the active leg muscles to measure actual work intensity and the subjects were asked to subjectively rate their perception of effort at various points during the task as well.

Sure enough, Marcora found strong correlations among the three variables of frowning muscle activity, leg muscle activity, and subjective ratings of effort. Thus he concluded, “These results suggest that frowning muscle activity reflects effort during physical tasks.”

Swiss triathlete Natascha Badmann won the Hawaii Ironman six times between 1998 and 2005. She was famous for smiling all the way through every race. This rare behavior was always thought of as a cute idiosyncrasy that had nothing to do with her performance. But is it possible that Badmann won the Hawaii Ironman six times in part because she smiled all the way through every race?

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About The Author: 

Matt Fitzgerald is the author of numerous books, including Racing Weight: How To Get Lean For Peak Performance (VeloPress, 2012). He is also a Training Intelligence Specialist for PEAR Sports. To learn more about Matt visit