Exercise: Effects on 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
- What are the short-term and
long-term effects of exercise on the respiratory system?
Table. MV (Minute Ventilation) and Rf (Respiratory Frequency) at
*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
|Short-term respiratory effects
|| Blood lactate
|| Duration of performance
||About 150 L/min
||Maximum mouth ventilation
|| Very high
|| A few minutes
||Heavy nose breathing
|| 1-2 hours
|Super health states
||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
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 and blood gases. What happens after exercise
of exercise on the respiratory system)? Since breathing is controlled by CO2,
the usual exercise effects for fit and healthy people are simple:
breathing after exercise becomes lighter and slower due to an adaptation of
the respiratory system and the breathing
centre to higher CO2 levels. As a result, the body-oxygen content increases
for many hours after the exercise. This especially relates to the next-morning body oxygenation, and this
is the main criterion of exercise efficiency, if someone decides to measure the
exact long-term effects of exercise on the respiratory system.
However, when very healthy and healthy people do exercise with strictly nasal
breathing, their blood gases during exercise are different in comparison with
mouth breathing. Arterial CO2 gets even higher, and arterial oxygen saturation
becomes slightly less in a dose-dependent manner. Nasal breathing (in and out)
slightly worsens the immediate performance and results, but is incomparably better in the
long run. Why? Intermittent hypoxic hypercapnic training, as in
case of nose breathing (in and out), is an
excellent way to improve VO2 max, body-oxygen content and achieve adaptation
of the breathing centre to higher CO2.
VO2max (definition)= the maximal oxygen uptake or the maximum
volume of oxygen that can be utilized by the human body in one minute during
maximal exercise. It is measured as milliliters of oxygen used in one minute per
kilogram of body weight (ml/kg/min). VO2max is usually ranged from
20-40 ml/kg/min (in unfit and ordinary subjects) and up to 80-90 ml/mg/min
(in elite endurance athletes). Physiologically, it is the most significant
parameter that predicts long-term endurance and performance in athletes.
One can try both these approaches (reduced nasal
breathing on some days and heavy mouth breathing in others) and compare the
effects of both types of exercise on your well-being. It is, for example, easy to discover that physical exercise with
strictly nose breathing significantly reduces pulse for the
same intensity level for any particular individual in comparison with
mouth or combined breathing. Hence, the positive effects of physical
exercise with nasal breathing only are immediate. They can be easily measured with
sport watches and other devices that can record heart rate during
Exercise and the respiratory system in sick people
analyzed before (see links below for over 40 medical studies that measured breathing in groups
of sick people), sick people have heavy and deep breathing at rest before exercise. Hence, their
have abnormal blood gases
prior to exercise. Usually they suffer from arterial hypocapnia
(low CO2 due to overbreathing) and (likely) mild arterial hypoxia, if they are chest breathers. (Chest
breathing, as we discussed, reduces oxygen level in the arterial blood.)
If they have problems with their lungs or ventilation-perfusion mismatch (as in a small group of patients
with severe asthma, bronchitis, or emphysema), their arterial CO2 is too high (up
to 50-60 mm Hg), but blood
oxygenation is low already at rest, causing dyspnea (shortness of breath
sensation) even during low intensity
Overbreathing at rest reduces their body-oxygen levels.
As a result, many people with diabetes, cancer, heart disease, chronic
fatigue and many other conditions have elevated blood lactate level at rest,
indicating the presence of cell hypoxia and anaerobic cellular respiration. Mild exercise generates
even more lactic acid due to initial oxygen deficiency. (This is the common
reason why the sick people do not like exercise.) As a result, since
the lactic acid level
is also controlled by the respiratory system, the body starts to remove bicarbonates
(CO2) from the blood by increased ventilation (metabolic acidosis). To maintain blood pH in the
normal range, the breathing centre intensifies minute ventilation to remove
some CO2 from the body. The breathing becomes disproportionally heavier
(the main short-term effect of exercise in the sick).
This is possible to observe in many sick people during exercise: heavy panting,
usually through the wide open mouth.
as we've previously discussed, further reduces the arterial and cellular CO2, creating brain hypoxia
and increasing heart rate. Nasal breathing, on the other hand, prevents CO2 and
nasal NO (nitric oxide) losses and improves brain and heart-oxygen content
provided that the intensity of exercise matches oxygen delivery.
The overbreathing caused by mouth breathing during exercise can continue for many hours
after exercise, if it is too intensive or anaerobic. Exercise with
low intensities are
better tolerated, but mouth breathing still negates any improvements in
heart and body oxygen level canceling positive long-term effects of
exercise on the respiratory system. It is normal then that severely-sick
individuals can easily die due to moderate or intensive exercise combined
with other hyperventilation-inducing lifestyle factors, including stress,
overheating, overeating before the exercise, drop in blood glucose level,
chest breathing, etc. It is not a surprise then that graded exercise therapy
has conflicting results so far.
There are many coaches and fitness instructors these days who teach their
athletes, students, and pupils to breathe in through the nose and out
through the mouth in order to improve long-term effects of exercise on the
respiratory system. This breathing technique for physical exercise is half-better than mouth breathing due to improved absorption of nitric oxide and
some increase in arterial CO2.
Conclusion. The effects of exercise on the
respiratory system and body-oxygen
content in the sick are generally negative due to mouth breathing. There
are, however, some positive effects of exercise due to perspiration, shaking of
the body, stimulation of the respiratory muscles and lungs, production of endorphins, and others.
Which exercise programs have the best short-term and long-term effects on the
respiratory system and body oxygen content?
Clinical experience of a large group of Soviet and Russian MDs suggests
that nasal breathing during exercise is the key factor that maximizes positive short- and
long-term effects of exercise on the respiratory system, and prevents any
acute episodes, including coronary spasms, angina pains, infarcts, strokes,
sport-induced asthma attacks, and seizures. Furthermore, nasal breathing
ensures absorption of nitric oxide generated in the sinuses and inhaled into
the lungs during nose breathing.
how nasal breathing provided good health for people in the past. Physical
exercise was the main factor that made the breathing and body-oxygen content of our predecessors much better. They were
exercising up to 8-12 hours per day (including walking, gardening, and
all type of activities where the whole body is involved in movement). Mouth breathing, as
you can easily see in old photos and movies, was a socially unacceptable habit.
Some evidence suggests that even competing athletes were breathing strictly
through the nose (in and out) during training sessions and sport contests.
With the advance of the industrial revolution during the last 100 years, the
amount of average exercise for people declined down to 10-60 min per day (this
includes walking). Furthermore, mouth breathing during exercise leads to heart
attacks, strokes, exercise-induced asthma attacks, and other exacerbations. As a
result, physical exercise, instead of being a health benefit, became a serious
hazard since we lost the habit of nose breathing. However, all the adverse long-term
and short-term effects of
exercise on the respiratory system can be virtually
eliminated via the use of strictly nasal breathing (in and out).
Hence, the oldest or traditional exercise programs (physical activity
with nasal breathing only) have the best effects on the respiratory system and body-oxygen
levels and general health of humans due to the high CO2 production rate,
arterial CO2 increases, and
adaptation of the breathing centre to higher CO2 with slower and lighter automatic breathing
for many hours later.
"Physical work, sport, and exertion increase CO2 production. Its
level increases in the blood, while oxygen decreases. The higher the
intensity, the stronger the excitement of the breathing centre and the deeper
the breathing, but it is only deeper formally. Breathing becomes not deeper,
but shallower: it is less in relation to metabolism. This is the reasoning
behind the usefulness of exercise and sport! During prolonged intensive
exercise the receptors, which control breathing, adapt to increased CO2. If
the person regularly works and toils, then he practically follows our method:
he is decreasing his breathing using exercise".
Dr. Buteyko lecture in the Moscow State University on 9 December
Physical exercise, according to Dr. Buteyko, is the main factor that
defines the long-term success of the student during breathing retraining due to
positive effects of exercise on the respiratory system. Since
a lack of physical exercise is the main cause of
hyperventilation in modern man, it is normal that daily duration of
physical activity has a correlation with personal-morning body-oxygen
content (the CP - control pause). Indeed, Buteyko and his colleagues
found that when their students achieved high CPs (e.g., up to 60 s)
and stopped doing breathing exercises, the stability of their CPs were
dependent on the amount of their daily physical exercise.
If you want to know how much exercise is possible and easy to have for super health states, and if you want to know 2 key factors, apart from nose breathing, that make exercise effective, you can find these details as your bonus content below here.
Sport and fitness articles:
breathing exercise for higher VO2max
- Increase VO2max by breathing differently at rest
- Exercise is
joy if the body is oxygenated at rest
- When exercise is 100% safe
for chronic diseases
- Why modern man gets little, if any, benefits from exercise
- Which exercise parameters increase body oxygenation
Clark AL, Volterrani M, Swan JW, Coats AJS
The increased ventilatory response to exercise in chronic heart failure:
relation to pulmonary pathology
Heart 1997; 77: p.138-146.
Departnent of Cardiac Medicine, National Heart and Lung Institute, London,
Conclusions. Patients with CHF have an increased ventilatory response at
all stages of exercise. Although this is accompanied by an increase in
VD/VT, there is hyperventilation relative to blood gases..
Banning AP, Lewis NP, Northridge DB, Elbom JS, Henderson AH
Perfusion/ventilation mismatch during exercise in chronic heart failure:
an investigation of circulatory determinants
Br Heart J 1995; 74: p.27-33.
Department of Cardiology, College of Medicine, University of Wales, Cardiff,
Results. Patients with CHF had a steeper VE/VCO2 [minute ventilation /
CO2 production rate] slope than normal controls: this was related inversely
to peak VO2, below 20 molL/min/l/kg.
Buller NP, Poole-Wilson PA
Mechanism of the increased ventilatory response to exercise in patients with
chronic heart failure
Heart 1990; 63; p.281-283.
The National Heart and Lung Institute and National Heart Hospital, London,
...There was a close
correlation between the severity of heart failure, determined as the maximal
rate of oxygen consumption, and the ventilatory response to exercise.
...This finding supports the concept that a significant
pulmonary ventilation/perfusion mismatch develops in patients with chronic
heart failure and suggests that the magnitude of this abnormality is
directly related to the severity of chronic heart failure.
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