Mouth Breathing Is the Key Cause of Exercise-Induced Asthma

All available medical data suggests that people with asthma are heavy breathers. They breathe about 2-3 times more air per minute than the medical norm. Let us review some of these studies.

In 1968 New England Journal of Medicine published results of a large clinical study (McFadden, 1968) in which breathing and blood gases of a group of people with asthma were investigated. The researchers found that all 101 asthmatics had chronic hyperventilation. Those asthmatics who had light or moderate types of the disease breathed 15 L of air per min or 2.5 times more than the official medical norm (6 L/min).

In 1995, American researchers from the Mayo Clinic and Foundation (Rochester) confirmed the same average value (about 15 l/min) for another group of patients diagnosed with asthma (Johnson et al, 1995). This study was published in the Journal of Applied Physiology.

More recently, researchers from the Department of Medicine at the University of Rochester School of Medicine and Dentistry (Rochester, NY, USA) discovered that 16 people with asthma had about 13 L /min for their minute ventilation rates. What are the effects?

Overbreathing reduces CO2 levels in the lungs and this immediately leads to bronchoconstriction (narrowing of airways: bronchi and bronchioles) since CO2 is a powerful dilator of airways. Hyperventilation also irritates airways due to mechanical friction of air 24/7 that promotes inflammation.

In addition, overbreathing reduces oxygen levels in body cells leading to predisposition to chronic inflammation of airways (caused by cell hypoxia produced by hyperventilation since hypoxia mediates chronic inflammatory response). Furthermore, tissue hypoxia suppresses the immune system. This leads to increased sensitivity of the immune system to innocent triggers (dust mites, airborne protein from cats and dogs, pollen, and so forth) and appearance of allergies and excessive production of mucus in airways. Hence, all components of asthma are caused by chronic hyperventilation.

What about physical exercise with mouth breathing for people with asthma? Mouth breathing during exercise further reduces CO2 levels in airways and worsens bronchospasm. In addition, large ventilation rates during exercise lead to overcooling and drying of air passages. This worsens inflammation.

All these factors contributes to symptoms of acute asthma exacerbations and exercise-induced asthma: bronchospasm (narrowing of airways: bronchi and bronchioles; caused by CO2 deficiency); increased inflammation of airways (caused by cell hypoxia produced by hyperventilation); excessive production of mucus in airways; reduced absorption of nasal nitric oxide.

Over 100 Russian MDs practicing the Buteyko medical therapy (the breathing technique that is approved by Russian Health Ministy for treatment of asthma) have found that strictly nose breathing prevents exercise-induced asthma exacerbations. Indeed, higher CO2 levels in airways, humidification and warming of inhaled air, and more gentle air flow prevent all negative effects of mouth breathing provided above.

Hence, they suggested that most exercise-induced asthma attacks are easily preventable: slow down the pace of exercise, but breathe only through the nose. You will get best benefits from exercise and increase your body oxygen levels. In addition, you will not need inhaler to reduce wheezing and feeling of suffocation.

Resources
Asthma Symptoms and Signs - Effects of breathing retraining on main symptoms of asthma (reduction in medication and elimination of all asthma signs)
Mouth Taping During Sleep - Instructions for prevention of asthma attacks at night
Bronchospasm and Chronic Constipation Have the Same Cause - and Solution

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