I'm no expert, but breathing is something I work on rather a lot. In part because it keeps my mind focused when I get untidy when I'm running. In relation to my cadence, I generally work on a odd/even (or even/odd) basis for my in/out breaths. Eg., when I'm running in a lower heart rate zone for endurance training, I'll breath in for 4 steps and breath out for 3. Up a notch on effort and I move to 3 breaths in and 2 breaths out, then another notch, 2 breaths in, 1 out. This way I'm not always landing on the same foot in the out-breath. I tend to thump my out-breath foot down harder, so this way I distribute the thumping equally over the run.
It may not be for you, but I've found it a helpful in three ways: I can easily judge my effort level based on the ratio; I distribute the force of my outbreath footfall; and the focus on the counting helps me retain my form when I'm getting sloppy. Good Luck. Jenn
i compare it to swimming, "only as big a breath as you need". better to make sure you're using the correct muscles. put one hand 10mm from your chest and the other hand 10mm from your belly then inhale deeply and quickly. as you inhale, which hits your hand first? < it should be your belly. >
I wrote something about this a few months ago. You can read it under "Breathing Technique Survey" in Run Training.