I began examining the yogc literature with a sense of wariness. Long ago, while working at the University of Wisconsin on a study of respiratory physiology, I came across a flat contradiction to one of modern yoga’s central tenets—that fast breathing floods the body and brain with revitalizing oxygen. In contrast, a textbook I was reading at the time said the pace of human respiration
‘can drop to one-half or rise to over one hundred times normal without appreciably influencing the amount of blood oxygenated.’
I see now that, in 1975, I underlined that passage quite heavily.
-The Science of Yoga by William J. Broad