The breathing techniques used by breathing coach were developed by Professor Konstantin Buteyko over 50 years ago and is often referred to as The Buteyko Method. He found that when people hyperventilate or over breathe they actually utilize the oxygen LESS effectively.
The more you breathe the less effective you are at utilizing the oxygen.
The less you breathe the more oxygen you can utilize.
Prof Buteyko's work also follows on from work carried out in 1905 by Christian Bohr, a Danish physiologist. The hypothesis that he put forward related to how oxygen is carried in the blood by Haemoglobin and has become to be know as the "Bohr Effect"