excerpt from above taken here.
5.Hold your breath underwater until you have to force exhale before taking your next breath. This happens just before and during the head turn for the breath. The more air in your lungs, the more buoyant you are. The more buoyant you are, the less drag you create. Don't blow bubbles underwater, even though that is what your first swim instructor likely taught you.
Do people still advocate this at senior coaching level? He seems to contradict all the other advice I have read about breathing out steadily and all the video I have seen of elite swimmers.
Am also wondering if anyone has a percentage guide to how full a lungful they take in for a breath as this obviously effects buoyancy. Terry talks about a bite of air but not sure what that means in terms of oxygen quantity as a bite can be small or large.