During boot camp I have a girl who is working hard but yawns excessively – I thought it could be improper breathing so I have been reminding her. I just gained a new client this week and during our one on one strength training session she also yawned excessively. Could there be an underlying health risk?
I find it to be the bodies cry for oxygen. If you have a pulse oximeter, hook it up to them next time they start with the yawns. I frequently notice a drop in SpO2 when this happens. Nothing to be concerned with in most cases; just be aware when its going on. They may just need a different recovery strategy.
Here is a link that may help: