Yawning During Exercise?

You may wonder why you find yourself yawning between sets... You can think of it as your brain’s natural air conditioner. As your body heats up during exercise, your brain combats the warmth by triggering a yawn.  

Yawning not only increases the amount of blood traveling to your brain, but the extra air also lowers the temperature of that blood, says study coauthor Andrew Gallup, Ph.D.