I hold my breath while doing planks and press ups. Its HARD! Usually when I hold my breath I relax as much as possible for a longer breath hold. This was a very different experience. The human body is so fascinating! I start with some warm up breath holds on the bed then I move on to the tricky stuff, holding my breath for as long as I can while doing press ups and planks. Do you think my muscles give out before I run out of air or the other way around?