The trouble began with industrialization. «Up until the past 100 or 150 years, our daily activities – farm chores, hunting animals, hard manual labor – required that we use our diaphragms as our main breathing muscle,» says Dr. Louis Libby, a pulmonary physician at the Oregon Clinic, in Portland. «In the past century we’ve become sedentary. We can go days without using our diaphragms. We’ve become lazy, sitting in front of computers and using the weaker intercostal breathing muscles in the rib cage for breaths that are incomplete but adequate for living.»
http://www.mensjournal.com/magazine/you-re-breathing-all-wrong-20130227