How do you breathe?

[underpants]

Put your left hand on your stomach
Put your right hand on your chest
Breathe
The left hand should be moving (breathing with the diaphragm) not the right hand

Read this yesterday

Most runners, says Solkin, are "chest breathers"-not "belly breathers." To help her clients see the difference, she has them run a mile at a pace that gets them huffing a bit. Then she has them stop and place one hand on their abdomen and one hand on their chest and watch. The lower hand should move with each breath, while the upper hand should remain relatively still (usually the opposite occurs). "Every time you breathe in, your belly should fill up like a balloon," says Solkin (see "Breathe Right"). "And every time you breathe out, that balloon should deflate. When you chest breathe, your shoulders get tense and move up and down. That's wasted energy-energy you should conserve for running."

http://www.runnersworld.com/article/0,7120,s6-238-267--12989-1-1-2,00.html

"I try to do Pilates twice a week," says 2004 Olympic marathoner Colleen de Reuck. "It stretches my intercostal muscles and lengthens my spine, which helps my breathing and my running."

Diaphragm techniques are on page two at the link