Erythropoietin, often known as EPO, is a hormone secreted by the kidneys in response to reduced oxygen levels in the blood. One of the functions of EPO is stimulating the maturation of red blood cells in the bone marrow, increasing oxygen delivery to muscles. Breath holding as demonstrated in The Oxygen Advantage is an effective way of stimulating the release of EPO, allowing you to fuel your blood with increased levels of oxygen and enhance your sports performance. Concentration of EPO can increase by as much as 24% when the body is subjected to lower oxygen levels using breath hold exercises.
A clear example of the relationship between breath holding and EPO production can be found in those suffering from sleep apnea. Sleep apnea is a condition involving involuntary holding of the breath after exhalation during sleep. Depending on the severity, the sleeper may hold his breath from 10-80 seconds and this may occur from 5-70 times an hour. During sleep apnea, the saturation of the blood with oxygen can reduce from normal levels of 98% to as low as 50%. The result of these reduced oxygen levels can cause an increase in EPO of 20%.
Of course, there is quite a difference between the condition of sleep apnea and the practice of breath holding to enhance sports performance. However, it is interesting to note the effect of breath holding (both voluntary and involuntary) on the production of natural EPO. Increasing EPO levels allows the blood to deliver greater amounts of oxygen to the muscles and is the natural equivalent of the illegal blood doping methods seen at the beginning of this chapter. The benefit of using breath holding as a performance enhancing exercise is that, unlike sleep apnea, conscious breath holding allows you to keep complete control over the frequency and duration of each hold. And, unlike blood doping, the EPO you produce using simple breathing techniques is free, effective and legal.