The Oxygen Advantage: The simple, scientifically proven breathing technique that will revolutionise your health and fitness

by Patrick McKeown

Gently exhaling prior to holding the breath reduces air content in the lungs, allowing a quicker build-up of carbon dioxide and eliciting a stronger response. While this reduces the length of time for which you can hold your breath, increased carbon dioxide has been shown to improve haemoglobin concentration by around 10 per cent compared to a breath hold with normal carbon dioxide levels. Higher levels of carbon dioxide in the blood can produce an even greater contraction of the spleen, resulting in an increase in the release of red blood cells and therefore the oxygenation of the blood. Increased CO2 in the blood also causes haemoglobin to dissociate the oxygen it is carrying more readily. As described by the Bohr Effect, an increase in carbon dioxide decreases blood pH and causes oxygen to be offloaded from haemoglobin to the tissues, further reducing blood oxygen saturation. Holding the breath on the exhale also capitalises on the benefits of nitric oxide by carrying the gas into the lungs rather than expelling it. By exhaling and holding the breath, nitric oxide is able to pool in the nasal cavity so that when breathing resumes, air laden with nitric oxide is inhaled into the lungs.