VO2max is the key factor in athletic endurance. Currently it is the best predictor of performance in many sports. However, only a very few people know that VO2max is tightly linked with the breathing pattern and body oxygenation of the athlete at rest. Hence, if the athlete changes their unconscious breathing pattern at rest, his VO2max will also change.
Patients with heart disease, diabetes, chronic fatigue, and many other diseases have low body oxygen content 24/7. They suffer from tissue hypoxia (low oxygenation), excessive anaerobic metabolism, and high blood lactate already at rest. Hence, when they have even light exercise, anaerobic energy production sharply increases, lactate quickly rises, and experiences of pain and physical exhaustion are the outcomes.
Oxygen delivery cascade (from outer air to body cells) and tissue oxygenation depend on our breathing. How? Hundreds of physiological studies proved that the more we breathe at rest, the less oxygen is delivered to tissues. Consider the basics of oxygen transport.
When we breathe more than the medical norm (which is 6 l of air per minute), our arterial blood is almost fully saturated with O2 (up to about 98%) and cannot get much more additional oxygen. However, during overbreathing we exhale (or lose) more CO2 and hypocapnia (CO2-deficiency) in all body cells causes 2 negative effects in oxygen transport:
1) Vasoconstriction: our blood vessels are CO2-sensitive and CO2 is a powerful vasodilator. (This effect explains, according to tens of medical publications, why we can easily pass out or faint due to heavy voluntary hyperventilation.)
2) The suppressed Bohr effect: the Bohr law governs oxygen release in tissues; O2 is mainly left in those parts and organs of the body which have high CO2 content (or metabolically active). When we hyperventilate, less O2 is unloaded in all tissues since CO2 is a chemical catalyser of this release.
Indeed, dozens of published studies found that ALL sick people with asthma, heart disease, diabetes, epilepsy, cystic fibrosis, etc., breathe at least 2-3 times more air than the norm and suffer, as a result of overbreathing, from tissue hypoxia (see my other articles for these references.) They usually breathe about 15 l/min instead of 6, while utilizing less than 10% of inhaled oxygen (over 90% is breathed out).
During maximum exercise humans can have up to 150 l/min for minute ventilation. Thus, if sick people start mild exercise and they require 10 times more energy than at rest, they will breathe about 10 times more or about 150 l/min, but this is near the human physiological limit.
People with normal minute ventilation at rest (6 l/min) during the same mild exercise (10 times energy expenditure increase) will breathe about 60 l/min. Such breathing is much lighter. It indicates their better fitness and can be done strictly through the nose.
It is not a surprise then that the amount of freely available oxygen in normal people is high or about 40-60 s (breath holding time after exhalation and without any pushing themselves for better numbers), while sick people can hold their breath for this special test (again, it involves usual exhalation and no stress at the end of the test) only for 10-15 s of oxygen. This completely confirms the main practical law of respiratory physiology: more breathing means worse tissue oxygenation.
However, if an athlete learns how to breathe much less than the norm 24/7 or only about 2 l/min at rest or during sleep for minute ventilation, their body oxygenation will be about 2-3 minutes. During the same mild exercise (with tenfold metabolic rate) their minute ventilation will be only about 20 l/min (or slightly more than the sick people breathe at rest). There are, indeed, two well known facts that (a) fittest athletes breathe less during exercise and (b) when an athlete is in his peak shape his breathing during races is much lighter.
Such breathing retraining can be achieved within 1-2 months. It will result in very light breathing at rest (only 3-4 breaths per minute even during sleep) and greatly increased VO2max values, up to 10-15%.
This short respiratory review in exercise physiology explains why numerous Soviet elite athletes, including many Olympic champions, used the Buteyko breathing method, as a secret weapon, for superior sport performance. Tens of Australian Olympians also learned the same breathing technique during recent years.