I’ve come to notice that every once in awhile, towards the end of a training session I’ll start to yawn. I can be breathing heavy and training hard but still manage to yawn.
This always happens towards the end of a work out when I’m more fatigued. It’s got to be a common thing because I know a few other guys that also yawn late workout.
Of course it’s due to a lack of oxygen. I’m just curious to see if anyone has ever actually researched and attained the facts.