I wouldn't call myself any sort of expert on this subject, but Seejay's reponse triggered a memory for me. When I took pilates in Houston, the advanced method of breathing was to breathe in upon exertion and breathe out on the return. We did lots of exercises in which we did a few reps first breathing out on exertion, and breathing in on return, then repeated the exercise for a few more reps reversing the breathing. The latter way of doing it is more difficult, requires more control of deep muscles, and more stability.

That seems to correlate with Seejay saying that exerting through mutliple breaths is more difficult. See, you're ahead of the curve, Ann....