Been thinking about the question of whether one should inhale as deeply as comfortably possible during swimming, or whether shallower breaths would be more advantageous from a physiologic standpoint.
What happens to venous return and cardiac output with deep inspiration vs. more relaxed? How about PaO2?
Anyone ever experimented in this regard or have any knowledge, theories, or wild guesses?
Ha, I read the title and thought “inspiration” in terms of “motivation.”
I haven’t an answer except the thought-free “when your face is in the water you should be blowing out” and when you breathe you suck air in… how much? I don’t know!
If you try and breathe too deeply you’ll slow yourself down.
So my un-scientific answer (at least this doesn’t require citations 
is just to breathe what feels right… most swimmers you see who take too-long breaths that interrupt and slow the stroke cycle aren’t exhaling completely when their faces are in the h2o