A while back, I did a Squat Rx blog post entitled "Breathing" in which I quote Zen author Sekida Katsuki and link to Squat Rx #10 in which I give tips on breathing and set-up for heavy squats. I've had many people mention the video to me and breathing is one of those topics that seems to be gaining attention in the strength and conditioning online community.
Breathing is so critical to long-term health, stress management, and performance that is surprising that it's taken us so long to give it proper attention. My guess is that most coaches fail to address breathing out of ignorance, and/or the false belief that "it just comes naturally". It DOES come naturally for young children but poor posture (sitting), stress, sedentary modern living, and overeating "unlearns" us.
There is certainly a lot to be mined on the subject of the breath for S&C writers, but here are the major lessons (as I see them) in exactly 10 words:
Diaphragmatic Breathing = All-Important
Inhalation = Excitation
Exhalation = Relaxation
Cessation = Focus