You’re psyched up. You’ve had pre-workout coffee, jogged up a sweat, mobilized, done your warm-up sets, hit your working weight, and after your first working set… you yawn.
Shake it off. Another set. You finish up, take your hands off the bar. You yawn.
Did you not warm up enough? Should you end the work out? Why would you yawn when you’re the most energized and sweaty and not-bored you’ve been all day? Believe it or not, yawning during workouts is surprisingly common and no, it’s not because you’re bad at exercise.
Why Do I Yawn During Exercise?
There’s actually a lot we don’t know about yawning. You might have heard we do it when our blood is low on oxygen or high in carbon dioxide: you take a deeeeep breath, you deliver a little injection of extra oxygen, your body is better able to power through. And hey, that would be a handy explanation for yawning during exercise.
But it turns out that’s not really why we yawn.(1) (Plus if it were, we’d be yawning through all of our workouts instead of panting.)
So why do we? If it’s just from fatigue, why is it contagious? If it’s to get more air, why have we seen fetuses yawning in the womb? There are some twenty different reasons that have been proposed for why we yawn and scientists have a tough time agreeing on the primacy of any of them — the main reason.
We could spend all article going into the various reasons proposed for why yawning is contagious but when it comes specifically to exercise, there’s one pretty popular reason why: yawning appears to cool your brain.(2) Studies have found yawns increase during increases in brain temperature and that yawning can restore the temperature to baseline. In other words, it’s kind of a natural air conditioner. (And yep, it turns out people do yawn less during colder weather.(3))
Dr. Andrew Gallup, an evolutionary psychologist and neuroscientist who has published several papers on the topic, has found that while studies haven’t shown that more oxygen or less carbon dioxide reduce contagious yawning, applying cold packs to the forehead does. He’s also participated in studies on rats that directly measure the temperature in the brain, and the results have supported the same conclusion.
Gallup told Furthermore that you’re less likely to yawn during steady state cardio and when you’re in a super hot environment, like Bikram yoga, because the outside air is less likely to cool you down.
Cooling Down
We should note that there are still a million and one proposed reasons why we yawn and even why we do it during exercise. Some experts, like Dr. George Bubenik at the University of Guelph, believe it’s caused by chemical compounds in the brain produced during workouts, maybe nitric oxide or serotonin. Gallup himself has also suggested it may be a way for the brain to get some blood back after it’s been diverted to the muscles during the workout.
But the most popular and well supported theory right now is that it cools a warm brain. That said, excessive yawning can be a sign of dizziness or a more serious issue with body temperature or blood flow, so make sure you see a doctor if it becomes a real concern.
References
- Provine RR, et al. Yawning: no effect of 3-5% CO2, 100% O2, and exercise. Behav Neural Biol. 1987 Nov;48(3):382-93.
- Shoup-Knox M, et al. Yawning and Stretching Predict Brain Temperature Changes in Rats: Support for the Thermoregulatory Hypothesis. Front Evol Neurosci. 2010; 2: 108.
- Massen JJ, et al. A thermal window for yawning in humans: yawning as a brain cooling mechanism. Physiol Behav. 2014 May 10;130:145-8.
