quote:

ORIGINAL: Aileen1968
Reading this thread just made me yawn.

quote:

ORIGINAL: LittleMeganV

Despite popular belief yawning does not mean you are tired or sleepy.

Your body has something called "Hypoxic Drive" When you body is not receiving enough oxygen, or not at all for that manner, it is starting to enter Hypoxia. Hypoxic drive is the measurement and reaction that your body conducts to keep you breathing when you are not voluntarily controlling (like holding breath or purposely hyperventilating). It's basically what keeps you breathing even while you are asleep or even in unconscious.

Now back to your original question. Your yawning during exercise is your bodies hypoxic drive kicking and trying to pull enough oxygen into keep up with the demand. You can try prevent the yawning by forcing yourself to take deeper breaths and more frequent, at an even pace.

While stretching - yoga or mediational breathing patterns will work well.

While weight lifting - breathing out when you exert and sucking in when you are resisting the weight back to the starting position is best. This will give you a good rhythm as well as help you with the actual exertion.

Cardio is a bit different in this case. If you are yawning during cardio, I am guessing you are doing only cardio exercise and not cardiovascular. In other words you getting your heart rate up (possibly into a fat burn zone) but you are not exerting enough to the point you are having to breath hard. I.e. (assumption here) you are doing stairs or walking, where as running, rowing or spinning will not only get your HR up but work your vascular (lungs) system as well.

I hope that helps some =)