Throughout my career in fitness, I have been presented with concerns and questions from clients that beg for thorough investigation. How many calories do I need to eat every day to lose weight? Should I work out three days a week or four? Will this ever get any easier? 

303 yawn featureMost recently: Why do I constantly yawn during exercise?

Long before I taught my own indoor cycling classes, I was an avid participant. Without fail, roughly 30 minutes into an all-out sweat fest, I would begin to involuntarily yawn. And keep yawning for the remainder of class. Luckily (or not, depending on how you see things) I was friends with the instructors, who would cry out in mock-offense, “Sorry, Jodilyn — am I boring you?”

This banter became a long-running joke. I’m not one in general to feel embarrassed, but I was curious as to why this was happening. And why I had absolutely no control over it.

The short answer is: our brain has become overheated and yawning is a quick method to cool it.

Here's a scientific, visual demonstration

Here’s a scientific, visual demonstration

Traditionally, doctors and fitness experts alike blew off this phenomenon of yawning while exercising as either a lack or need for oxygen or high levels of carbon dioxide. Neither, as it turns out, is right. In a study initiated by the Department of Psychology at the University of Albany, probes were implanted in the frontal cortex of rats to determine whether or not yawning acts as a natural regulator of brain temperature. Readings were recorded before, during, and after cute little rat yawns (really, any animal yawning is adorable), and suggested that, in fact, yawning was successful at restoring the brain’s baseline temperatures.

When we exercise, our contracting muscles generate heat — some estimate the average body temps to reach as high as 104 degrees. The processes of evaporation (sweating) and convection (hogging the fan) are effective, but may not be enough to cool the body quickly if needed. So the body enlists the reinforcement: yawning.

Our incredibly brilliant, resourceful bodies know what to do. Don’t try to stifle your workout yawns, no matter how hard someone might tease you in class. Dish it right back. Tell them that either: your over-stimulated brain is cooling off, or they are mind-numbingly dull. Let them guess the answer.

PT-color-headshot-I3Jodilyn Stuart is the Health & Sports Senior Staff Writer for 303 Magazine, owner of ModaBody Fitness, and has been a professional fitness geek since 1997. If you have questions, feel free to email at: [email protected]