Exercise and the Respiratory System
Effects of physical activity and sports
on the respiratory system mainly depend on changes in alveolar CO2
levels. Here, after analyzing basics of oxygen transport (changes in CO2 and O2
concentrations in the blood and cells), we are going to provide clear and simple answers to the following questions:
- What are the exact criteria that determine the long-term positive effects of exercise on overall health and well-being?
- Are these criteria different in healthy and sick people?
- If exercise is healthy, why do thousands of sick people die every year from coronary-artery spasms, anginas, infarcts, strokes, exercise-induced asthma attacks and many other acute exacerbations of diseases during or following physical exercise?
- Is graded exercise therapy useful for all patients?
- What is going on with the respiratory system of these people during exercise?
- What are the short-term and long-term effects of exercise on the respiratory system?
Table. MV (Minute Ventilation) and Rf (Respiratory Frequency) at rest
|Condition||MV, L/min||Rf, breaths/min||Oxygen
|Breath pattern|| References
(click below for details)
|Diseases*||12-18||>18||<12 %||Overbreathing||Over 40 studies|
|Healthy||6-7||10-12||25 %||Normal||Results of 14 studies|
|Norm||6||12||25 %||Normal||Medical textbooks|
*Chronic diseases include heart disease, diabetes, asthma, COPD, cystic fibrosis, cancer, and many others. Study Hyperventilation Syndrome for references and numbers.
As it is easy to observe, heavy breathing at rest results in relatively heavy breathing during exercise and that makes moderate or intensive exercise in the sick very difficult or impossible.
Table. Minute ventilation during moderate exercise (15-fold metabolism)
|Short-term respiratory effects||Blood lactate||Duration of performance|
|Chronic diseases||About 150 L/min||Maximum mouth ventilation||Very high||A few minutes|
|Normal breathing||90 L/min||Heavy nose breathing||Elevated||1-2 hours|
|Super health states||30 L/min||Easy nose breathing||Nearly normal||Many hours|
If you attend a typical mass running event or open marathon, you will notice numerous ambulances with paramedics, who are ready to provide rescue help and oxygen, regardless of the details of the chronic disease (heart disease, stroke, seizures, exercise-induced asthma, and so forth). Whatever the condition, low brain and heart oxygen levels are most likely physiological causes of possible deaths. Hence, the main questions then are: What are the factors that define effects of exercise on the respiratory system? What is going on with blood gases or O2 and CO2 in the blood and body cells? The answers depend on the pre-existing respiratory parameters and levels of blood gases before and after exercise.
Exercise and the respiratory system in healthy people
Consider the short-term effects of exercise in healthy people. Textbooks on exercise physiology suggest that, in fit and healthy people, arterial CO2 levels rise slightly with light, moderate, medium and sub-maximum exercise intensity levels regardless of the route of breathing during exercise (mouth or nasal or combined). Since CO2 is the powerful vasodilation agent, expanded arteries and arterioles improve blood and O2 delivery to all vital organs of the human body, including the heart and brain. Vasodilation ensures aerobic respiration in body cells making it possible for healthy people to enjoy all the benefits of aerobic exercise without any major problems related to tissue hypoxia causing excessive blood lactate, muscle spasms, injuries, low recovery rates, overexcitement, stress, poor sleep later, etc.
Hence, healthy people experience immediate positive effects of exercise on the respiratory system*/