Breathing and oxygenation in healthy and sick people
If you observe modern exercising people, you will see that over 97% of them breathe through the mouth. Is this a problem? Breathing is about oxygenation of tissues. Hence, let us consider oxygenation and breathing in health and disease.
Clinical evidence clearly showed that patients with heart disease, asthma, cancer, diabetes and many other chronic conditions breathe at rest about 2, 3, or 4 times more air than the medical norm. You can easily observe their noisy and labored breathing. At the same time, low body oxygenation is the normal feature for all these patients.
Healthy people breathe little (4-6 l/min), but their oxygenation is much better. This is the paradox of breathing: those who breathe less have more oxygen in tissues.
While measurements of tissue oxygenation require special equipment, you can do a simple test that is very sensitive to tissue oxygenation. Measure your stress-free breath holding time. How it is done? The prominent Russian physiologist who worked for the first Soviet spaceship missions Dr. KP Buteyko, MD was the head of the respiratory laboratory in the 1960s. He stated about 40 years ago, "Oxygen content in the organism can be found using a simple method: after exhalation, observe, how long the person can pause their breath without stress."
After your usual exhale, pinch your nose and count your CP (control pause) in seconds. Keep nose pinched until you experience the first desire to breathe. Practice shows that this first desire appears together with an involuntary push of the diaphragm or swallowing movement in the throat. (Your body warns you, "Enough!") If you release the nose and start breathing at this time, you can resume your usual breathing pattern (in the same way as you were breathing prior to the test). Do not extend breath holding too long. This is the most common mistake. You should not gasp for air or open your mouth when you release your nose. The test should be easy and not cause you any stress. The CP test does not interfere with your usual breathing.
Dozens of medical studies proved that stress-free breath holding time is short in the sick and invariably long in the healthy. In my view, the CP test is the best health test that reflects health of the person.
Now you can easily confirm that sick people breathe heavy, but the CP (index of oxygenation) is small: 1-10 s of oxygen in severely sick patients, 10-20 s CP in people with mild asthma, heart disease, or diabetes. Healthy people have more than 30 s of oxygen. Breathing of healthy people is invisible and inaudible, but they have much more O2 in tissues. Why? The reasons of better oxygenation are sufficient body CO2 stores. CO2, the gas we exhale, dilates blood vessels (see tens of medical studies about this effect - http://www.normalbreathing.com/CO2-vasodilation.php) and controls O2 release by red blood cells in tissues (the Bohr law - http://www.normalbreathing.com/CO2-Bohr.php). Hence, those who breathe little have better oxygenation.
This fact is well-known to medical doctors, but most people have a superstition or fantasy that deep or big breathing provides us with more oxygen. However, if you take 100 fast and deep breaths in succession, you can pass out or faint due to ... hypoxia (low oxygenation) of the brain. There are dozens of medical studies that confirmed this effect. Hyperventilation is a health hazard. When we start to hyperventilate, arteries and arterioles constrict and less oxygen and blood delivered to all vital organs, the brain included. Moreover, low CO2 values suppress O2 release by red blood cells (the suppressed Bohr effect). This further reduces oxygenation of the brain, heart, liver, kidneys, and all other vital organs.
Doctors who know when and how to exercise
Going back to health benefits of exercise, about 200 Russian doctors have been practicing the Buteyko self-oxygenation breathing therapy for decades. (The therapy was developed by Dr. Konstantin Buteyko, MD). They taught hundreds thousands of Russian patients and accumulated huge clinical experience how to restore body oxygenation in the sick. These doctors conducted millions of CP tests. They found that physical exercise is the main factor that helps us to increase body oxygenation (the after-effect of exercise), but only if we breathe through the nose. How and why?
When we breathe through the nose during the exercise, the human body has more CO2 in the lungs, blood and tissues because it is more difficult to breathe and we generate huge amounts of CO2. Hence, the breathing centre adapts to higher CO2 concentrations. After exercise, breathing becomes lighter (breathing is mainly regulated by CO2) and we have more oxygen in the body. The additional effect of nasal breathing relates to nitric oxide, a powerful hormone produced in nasal passages. Nitric oxide also dilates blood vessels, modulates the immune system, and normalizes transmission of nerve signals. When we breathe through the mouth, we cannot utilize our own nitric oxide. (You may know that the popular heart drug nitroglycerine reduces blood pressure and prevents heart attacks only due to its chemical transformation into nitric oxide.) No wonder, that the person who breathes through the nose during exercise looks smarter than those who are mouth-breathers.
These Russian Buteyko breathing doctors discovered that patients with heart disease can die during exercise if they breathe through the mouth. Similarly, exercise-induced asthma attacks are possible only when asthmatics breathe through their mouth during physical exercise. Hence, we should breathe only through the nose 24/7.
What are the other suggestions of these oxygenation doctors in relation to exercise?
Generally, patients with less than 10 s of oxygen in the body are not able to exercise at all. Health of these patients can be improved with Buteyko breathing exercises that boost body oxygenation. When oxygenation is better (between 10 and 20 s), patients can walk with nasal breathing and walking is a very positive factor for this group of people. In fact, patients with mild asthma and heart disease can recover in 2-4 weeks, if they start walking with nasal breathing for 5-6 hours every day. (They also should prevent mouth breathing at night and sleeping on one's back for faster recovery.)
Jogging and other intensive activities (cycling, swimming, rowing, etc.) are possible when the CP is 20 s or more. If we have less than 20 s, we cannot exercise with nasal breathing and should not do any rigorous exercise. (According to my experience, only a few people in a hundred can exercise, while breathing through the nose, when their oxygenation is less than 20 s.) But when we have more than 20 s of oxygen, exercise becomes the main tool for further health improvement. Hence, these doctors greatly encourage 2-3 hours of rigorous physical activity with nasal breathing every day.
When we breathe through the mouth, intensive workouts may have very moderate positive health effects for exceptionally fit athletes. They can slightly improve body oxygenation. But most people are not fit these days. Many people exercise for the sake of better health and ... breathe through their mouth almost nullifying the expected health benefits. Why? The gas exchange between the lungs and the outer air is much faster for mouth breathing. CO2 level in the blood gets smaller than at rest. Breathing gets heavier in comparison with metabolic rate. In addition, nitric oxide is not utilized from nasal passages. These are the reasons why people can have asthma or heart attacks, or stroke during physical activity or hours later if they breathe through the mouth.
Resources
Oxygen Remedy Webinars
Cystic Fibrosis Life Expectancy, Stages and Breathing Patterns
The Only Cause of Dysnea Discovered - Knol from Google.com
www.NormalBreathing.com has 100's of Western medical references, tables, graphs, quotes, charts, dozens of results of published clinical trials, analysis of numerous respiratory techniques and devices, free Buteyko breathing exercises, manuals, techniques, lifestyle modules and further resources for better body oxygen content and health.