Normal Breathing Pattern
”The perfect man breathes as if he is not breathing” Lao Tze (604 - c.521 BC), Chinese Philosopher
We discussed normal breathing parameters in Section Homepage. If you have healthy friends or relatives, you can easily observe that their breathing is slow, regular, nasal only, diaphragmatic, invisible and shallow (no chest or belly movements), and inaudible (no panting, no wheezing, no sighing, no yawning, no sneezing, no coughing, no deep inhalations or exhalations). They take small inhalations and then relax for the exhalation. The exhalation is followed by an automatic pause (or period of no breathing) of about 2 s. The usual body oxygenation index or CP (Control Pause) of healthy people is about 40 s for the medical norm and 60 s for the Buteyko norm.
The durations of inhalations and exhalations, breathing rate, amount of air inhaled per breath and other parameters are individual. Many healthy people can have the following parameters of the breathing cycle: inhalation (about 1.5-2 s); exhalation (1.5-2 s); automatic pause of almost no breathing (2 s); the depth of inhalation is about 500-600 ml; and breathing frequency (or Rf - respiratory frequency) is about 10-12 breaths/min. The international physiological norm for the breathing rate is 6 l/min (for a 70-kg man). References for medical textbooks that provide these values are below.
This picture shows 4 breathing cycles of normal breathing: inhalation (the upward lines), exhalation (the downward lines) and automatic pause (the almost horizontal lines) accompanied by relaxation of all breathing muscles.
As mentioned above, the person with such breathing is going to have about 40 s CP. This indicates good oxygenation of tissues.
Most of the job of inhalation (up to 80-90%) is done by the diaphragm, the main breathing muscle. Exhalation is passive and accompanied by relaxation of all breathing muscles. These parameters of normal breathing were established about 100 years ago. Published medical articles found that in the 1920-1930's, normal subjects were breathing even less air at rest than the medical norm (6 L of air per minute). You can find these 1920-1930's studies in the Table that shows historical changes in minute ventilation of ordinary subjects. Some old medical textbooks suggested 4 l/min as normal for healthy people.
Note that minute ventilation of modern healthy people is still nearly normal (about 6-7 L of air in one minute) as this Table (Minute Ventilation in Healthy Subjects) indicates. Hence, they naturally have normal breathing pattern at rest and good oxygen stores in their cells and tissues.
Medical textbooks references
Ganong W, Review of medical physiology; 15-th ed., 1995, Prentice Hall Int., London.
Guyton A, Physiology of the human body; 6-th ed., 1984, Suanders College Publ., Philadelphia.
McArdle W, Katch F, Katch V, Essentials of exercise physiology (Second edition); Lippincott, Williams and Wilkins, London 2000.
Straub N, Section V, The Respiratory System, in Physiology, editors. R Berne & M Levy, 4-th edition, Mosby, St. Louis, 1998.
Summary of values useful in pulmonary physiology: man.
In the Section: Respiration and Circulation, ed. by P Altman & D
Dittmer, 1971, Bethesda, Maryland (Federation of American Societies for
Experimental Biology).