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A Comprehensive Breathing Myths Guide

Updated: Apr 19


Breathing ensures healthy CO2 levels. The main functions of breathing are gas exchange and acid-base (pH) regulation. The respiratory system exchanges oxygen for carbon dioxide (CO2) cells release during metabolism. CO2 regulates our physiology by increasing nitric oxide and oxygen delivery when tissues are more active. Our body uses 85-88% of CO2 to ensure a healthy acid-base balance, making gas exchange possible through the Bohr effect (Khazan, 2021). We debunk 14 breathing misconceptions to improve biofeedback and neurofeedback training for health and performance. These breathing myths include: 1. Carbon dioxide is a toxic waste gas we should remove. 2. We need more oxygen. 3. Oxygen intake is the primary role of breathing. 4. Take deep breaths. 5. Always breathe through your mouth. 6. Longer exhalations during slow-paced breathing increase HRV. 7. Longer exhalations are healthier.

8. 100% oxygen saturation is better than 98%.

9. Pulse oximeters are accurate for everyone.

10. Holding your breath increases lung capacity.

11. Slow-paced breathing is healthy for everyone.

12. Abdominal breathing should feel more natural than thoracic breathing.

13. You should breathe slowly throughout the day. 14. The Wim Hoff Method (WHM) involving rapid breathing and cold exposure is healthy. This post draws on Dr. Inna Khazan's extensive lectures and writing on healthy breathing. Dani S@unclebelang on drew the beautiful WEBTOONs illustrating these myths.

Dr. Inna Khazan

Myth 1. Carbon dioxide is a toxic waste gas we should remove.

CO2 is not toxic in the concentrations produced by the body under normal conditions. CO2 is crucial in the human body's respiratory and cardiovascular systems. It is a key component of the blood's buffering system, helping to maintain pH balance. The concentration of CO2 in the blood regulates breathing rates; low levels (hypocapnia) can lead to respiratory alkalosis, while high levels (hypercapnia) stimulate breathing to remove excess CO2, maintaining homeostasis. CO2 is essential for the Bohr effect. The Bohr effect describes how the presence of CO2 facilitates the release of oxygen from hemoglobin, enhancing oxygen delivery to tissues. This effect demonstrates CO2's critical role in ensuring that oxygen is efficiently supplied to where it is most needed in the body. Our bodies require end-tidal CO2 levels of 35-45 mmHg (torr) to maintain homeostasis.

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Myth 2. We need more oxygen.

Under normal conditions, most people's blood is saturated with oxygen at about 95-100%. The issue is not the amount of oxygen in the blood but how effectively the body's tissues utilize it. This is influenced by factors like the Bohr effect, where CO2 levels help to release oxygen from hemoglobin. Rather than needing to maximize oxygen intake, maintaining adequate levels of CO2 is crucial for efficient oxygen usage. Overbreathing expels too much CO2, leading to a condition known as hypocapnia, which can reduce blood flow to the brain and impair oxygen release by hemoglobin, paradoxically leading to symptoms of oxygen shortage. We do not need more oxygen! (Khazan, 2021). Near sea level, the air healthy clients inhale contains 21% oxygen, while the air they exhale has 15%. We only use ¼ of inhaled oxygen and don’t need more. We need to conserve CO2 by retaining 85-88% of it.

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Myth 3. Oxygen intake is the primary role of breathing.

The myth that the primary role of breathing is oxygen intake oversimplifies the complex functions of the respiratory system. While obtaining oxygen is crucial to breathing, it's not the sole purpose.

Equally important to inhaling oxygen (O2) is exhaling carbon dioxide (CO2), a byproduct of cellular metabolism. Removing CO2 from the body is critical for maintaining the acid-base balance in the blood, preventing acidosis, and ensuring that cellular processes function correctly.

Breathing plays a pivotal role in regulating the pH level of the blood. By adjusting the rate and depth of breathing, the body can control the amount of CO2 expelled, directly influencing the blood's acidity. This regulation is vital for the proper functioning of enzymes and metabolic processes.

Breathing supports the efficient exchange of gases in the lungs, where oxygen is absorbed into the bloodstream, and CO2 is released for exhalation. This exchange is crucial for metabolic activities and energy production within cells.

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4. Take deep breaths.

The key to healthy breathing lies in its efficiency, not its depth. Efficient breathing, often through the diaphragm (diaphragmatic breathing), allows for optimal gas exchange in the lungs. The quality of the breath, involving complete oxygen and CO2 exchange, is more important than the volume of air inhaled. Breathing deeply without maintaining the correct balance between oxygen and carbon dioxide can disrupt the body's gas equilibrium. The physiological benefits of breathing are maximized when there's a proper balance, supporting cellular respiration and maintaining blood pH levels.

For some individuals, especially those with anxiety or panic disorders, taking deep breaths without proper technique or guidance can lead to hyperventilation. This excessive breathing can decrease CO2 levels too much, potentially causing symptoms like dizziness, palpitations, or increased anxiety.

Discourage typical deep breathing, where a client inhales a massive breath and inevitably exhales too quickly because this promotes overbreathing and expels too much CO2 (Khazan, 2021). Our colleague Don Moss no longer uses "deep" when coaching breathing (Moss, 2022).

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Myth 5. Always breathe through your mouth.

Encourage your clients to inhale through the nostrils to filter, moisten, and warm the air. They should exhale through the mouth or nose depending on training goals and health. The nose acts as a natural filter, trapping dust, allergens, and other particulate matter before they can enter the lungs. Nasal passages also humidify and warm the air, protecting the respiratory tract from irritation and infection. Mouth breathing bypasses these natural defenses.

Breathing through the nose releases nitric oxide, a gas that enhances the body’s ability to transport oxygen by dilating blood vessels. This process improves oxygen uptake in the blood, contributing to better overall cardiovascular health. Mouth breathing does not offer this benefit.

Chronic mouth breathing can lead to dry mouth, increasing the risk of dental decay and gum disease because saliva, which protects against bacteria and aids digestion, is reduced. Furthermore, the altered posture of the tongue and jaw can contribute to malformations in children, such as dental malocclusions and facial deformities.

Nasal breathing helps regulate the volume of air breathed and maintains adequate levels of CO2 in the blood, which is necessary to efficiently release oxygen from hemoglobin to the body’s tissues (Bohr effect). Mouth breathing can lead to overbreathing and a reduction in CO2 levels, impairing oxygen delivery.

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Myth 6. Longer exhalations during slow-paced breathing increase HRV.

Zachary Meehan and Fred Shaffer systematically reviewed 11 inhalation-to-exhalation (I/E) ratio HRV studies using the revised Cochrane risk-of-bias tool. They concluded that longer I/E ratios do not reliably increase HRV.

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Myth 7: Longer exhalations are healthier.

We are unaware of well-controlled randomized controlled trials (RCTs) confirming the health benefits of longer exhalations. "Well-controlled" means the investigators confirmed that participants breathed at the same rates and followed inhalation-to-exhalation (IE) rate instructions. Below are searches using ChatGPT, Gemini, and Perplexity. We excluded studies that only reported on HRV changes since the best-controlled studies (Meehan & Shaffer, 2024) showed no effect.




Professionals claiming that longer exhalations are healthier and equal IE ratios are harmful have not shown their receipts. For example, do longer exhalations lower blood pressure or blood sugar? Do equal IE ratios raise blood pressure or blood sugar? The widely-used Institute of HeartMath Coherence Coach breathing pacer has used equal IE ratios for decades without incident. Individual Health Conditions: For people with respiratory conditions, such as COPD or asthma, excessively long exhalations can lead to challenges like incomplete lung emptying or increased breathing work, which might exacerbate their condition.

Activity and Demand: During physical activity, the body's demand for oxygen increases, necessitating a quicker breathing rate. Longer exhalations in such scenarios can reduce oxygen intake efficiency, potentially impairing performance and leading to faster fatigue. Effective breathing involves adapting to the body’s needs and balancing oxygen intake and carbon dioxide expulsion. The ideal breathing pattern varies depending on current activities, emotional state, and health conditions.

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Myth 8: 100% oxygen saturation is better than 98%.

Oxygen saturation measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. When oxygen saturation exceeds 98%, more oxygen and nitric oxide are bound to hemoglobin and not released for use by the body's cells. Oxygen saturation between 95-98% is ideal for most clients. For clients with chronic conditions such as chronic obstructive pulmonary disease (COPD), saturations closer to 100% might be inappropriate. In such cases, excessively high oxygen levels can suppress the respiratory drive, leading to elevated carbon dioxide levels and respiratory acidosis.

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Myth 9: Pulse oximeters are accurate for everyone.

Physicians use oximetry to identify patients who need supplemental oxygen. Since this technology was developed using a racially non-diverse population, it should not be surprising that occult hypoxemia (undetected blood oxygen levels below 88%) was three times more likely in Black than White patients in two large cohorts. During the COVID-19 pandemic, patients of color were sent home instead of intensive care units due to inaccurate oxygen saturation measurements. Misleading pulse oximeter readings delayed treatments, increased hospitalization rates, limited access to necessary medical interventions, and exacerbated existing health disparities.

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Myth 10: Holding your breath increases lung capacity.

Lung capacity is the maximum air the lungs can hold, typically measured in liters. It includes several components, such as tidal volume (air inhaled and exhaled during normal breathing) and vital capacity (the maximum air exhaled after a maximum inhalation).

Total lung capacity is determined largely by genetics, age, sex, and physical conditioning, but environmental factors and overall health also influence it. Holding your breath can increase tolerance to higher carbon dioxide (CO2) levels. It may temporarily affect how comfortably you can hold your breath (breath-holding time), but it does not increase the lung's capacity to hold air.

Frequent and intense breath-holding can be risky, especially without proper training and supervision. It can lead to a dangerous condition known as hypoxia (oxygen deprivation), which, in extreme cases, can cause unconsciousness, brain damage, or even death.

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Myth 11: Slow-paced breathing is healthy for everyone.

Slow-paced breathing can be highly beneficial for stress reduction and cardiovascular health, but it is not a one-size-fits-all remedy. Its appropriateness depends on individual health conditions, activity levels, and specific situations. Personalized approaches and, in some cases, medical guidance are recommended to ensure that breathing practices are both safe and effective.

Individual Health Conditions: Slow breathing might disrupt the acid-base balance in people with metabolic disorders like diabetes or kidney disease and respiratory disorders like asthma or COPD.

Adaptation to Activity Levels: During physical exertion, slow breathing might not provide sufficient oxygen intake or carbon dioxide expulsion, potentially causing decreased performance and discomfort.

Risk of Hypoventilation: Excessively slow breathing can lead to hypoventilation, especially if the breaths are not deep enough. This can increase blood carbon dioxide levels, causing headaches, confusion, and dizziness.

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Myth 12: Abdominal breathing should feel more natural than thoracic breathing.

Although abdominal breathing has many health benefits and is effective for relaxation and efficient breathing, suggesting it should feel more natural than thoracic breathing for everyone is an oversimplification. Various factors influence breathing patterns, including physical structure, health conditions, activity levels, and learned behaviors. Training: Abdominal breathing can be learned and may become more natural with practice, especially in contexts like yoga or meditation. However, initially, it might not feel as natural, particularly if one has been predominantly a thoracic breather Physical Differences: People have different physical and anatomical structures, affecting how comfortable or natural a particular breathing style may feel. For some, thoracic breathing may feel more natural, especially during certain activities or due to their physical conditioning.

Health Conditions: Those with respiratory issues or certain medical conditions might find abdominal breathing more difficult or less natural. For example, individuals with obesity or abdominal pain may find thoracic breathing easier.

Activity Level: During vigorous exercise or stressful situations, thoracic breathing can feel more natural and effective in meeting the body’s increased oxygen demands. Conversely, abdominal breathing is more beneficial in calm, restful states or during relaxation and stress reduction practices.

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Myth 13: You should breathe slowly throughout the day.

Overly slow breathing, especially if not matched to the body’s current needs, can lead to hypocapnia, where carbon dioxide levels in the blood fall too low. This can cause respiratory alkalosis, leading to lightheadedness, tingling in the extremities, confusion, and muscle twitching. Slow breathing could be hazardous if your client suffers from diseases that produce metabolic acidosis, like diabetes and kidney disease, or respiratory acidosis, like chronic obstructive pulmonary disease. Overbreathing attempts to compensate for abnormal acid-base balance and slow-paced breathing could endanger health.

Maintaining a slow breathing rate regardless of physical demands can prevent the body from properly adjusting to different activities, potentially reducing overall physical efficiency and responsiveness. Adopting an adaptive breathing strategy that adjusts to current needs is more beneficial. For instance, employing slow breathing techniques during rest, stress, or meditation can be very beneficial, but allowing the body to increase breathing rate during exercise or excitement is crucial for optimal physiological function.

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Myth 14: The Wim Hoff Method (WHM) involving rapid breathing and cold exposure is healthy.

The Wim Hof Method (WHM), popularized by Wim Hof, also known as "The Iceman," involves rapid breathing techniques, cold exposure, and meditation. While it claims numerous health benefits and has garnered a substantial following, it's important to approach the method with a nuanced understanding of its potential benefits and risks.

Hyperventilation Risks: The rapid breathing aspect of the WHM can lead to hypocapnia, a state of reduced carbon dioxide in the blood, which can cause symptoms like dizziness, tingling, confusion, and even fainting.

Cold Exposure Risks: While brief cold exposure can boost the immune response and metabolism, prolonged exposure without proper acclimatization can lead to hypothermia and other cold-related injuries. Individuals with cardiovascular issues might be at higher risk when exposed to extreme cold. Medical Conditions: Individuals with certain health conditions, such as cardiovascular diseases, respiratory issues, or high blood pressure, should be cautious and consult healthcare providers before attempting the WHM.

Lack of Scientific Consensus: Although some studies support aspects of the WHM, the research is not extensive enough to conclusively determine its purported benefits or long-term effects. More rigorous, peer-reviewed studies are needed to understand its impacts on various health aspects fully.

The claim that the Wim Hof Method is universally healthy overlooks the complex interplay of individual health conditions, the risks associated with extreme practices like rapid breathing and cold exposure, and the lack of comprehensive scientific validation. While there may be benefits, they must be weighed against potential risks, especially those with underlying health issues. Anyone interested in the WHM must approach it with caution, ideally under the guidance of a healthcare professional, and to consider their personal health status and risks.

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Biofeedback and neurofeedback training may benefit from identifying and correcting your clients' breathing myths. Breathing misconceptions can interfere with training by promoting overbreathing, ignoring your body's interoceptive feedback, and overriding your breathing reflex. Shifting to a healthy breathing pattern corrects overbreathing by conserving 85-88% of CO2. Conserving CO2 lowers blood pH, weakens the bond between hemoglobin and oxygen, and increases nitric oxide and oxygen delivery to body tissues courtesy of the Bohr effect. Healthy breathing dilates blood vessels, slows heart rate (HR), increases respiratory sinus arrhythmia (RSA) and heart rate variability (HRV), and lowers blood pressure (BP).


abdominal breathing: a breathing technique that involves breathing using the diaphragm rather than the upper chest muscles. As the diaphragm contracts and moves downward, the abdomen expands, allowing for fuller lung expansion and more efficient air exchange. carbon dioxide: a gas produced by cellular metabolism, crucial for regulating breathing, maintaining blood pH balance, and facilitating oxygen delivery to tissues.

diaphragm: the dome-shaped muscle whose contraction enlarges the vertical diameter of the chest cavity and accounts for about 75% of air movement into the lungs during relaxed breathing.

effortless breathing: Erik Peper’s relaxed breathing method in which the client uses about 70% of maximum effort, attention settles below the waist, and the volume of air moving through the lungs increases. The subjective experience is that "my body breathes itself."

end-tidal CO2: the percentage of CO2 in exhaled air at the end of exhalation.

hypocapnia: a condition characterized by abnormally low levels of carbon dioxide (CO2) in the blood, typically resulting from excessive breathing (hyperventilation). Hypocapnia can lead to symptoms such as dizziness, tingling in the limbs, confusion, and in severe cases, seizures. inhalation-to-exhalation (IE) ratio: the proportion of time spent on inhaling (breathing in) compared to exhaling (breathing out) during a breathing cycle.

metabolic acidosis: A disturbance characterized by a decrease in the body's bicarbonate levels or an increase in the production of acids, leading to a reduction in the arterial blood pH below 7.35. This condition can result from increased acid production (such as ketoacidosis or lactic acidosis), reduced kidney acid secretion, or significant bicarbonate losses.

nitric oxide: signaling molecule produced in the body that promotes vasodilation, enhances blood flow, supports immune defense, and is involved in regulating pulmonary function.

overbreathing: subtle breathing behaviors like sighs and yawns reduce end-tidal CO2 below 5%, exceeding the body's need to eliminate CO2.

oxygen saturation: a measure of the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. respiratory acidosis: a state in which decreased ventilation (hypoventilation) leads to an increase in carbon dioxide concentration and a decrease in blood pH. This condition is often due to impaired lung function, chest injuries, or diseases that affect the respiratory muscles or control of breathing.

thoracic breathing: breathing that primarily uses the muscles of the upper chest, with minimal engagement of the diaphragm. The chest expands and rises significantly during thoracic breathing, common during intense physical activity or acute stress. This method is less efficient regarding oxygen and carbon dioxide exchange than diaphragmatic breathing.

torr: the unit of atmospheric pressure, named after Torricelli, which equals 1 millimeter of mercury (mmHg), is used to measure end-tidal CO2. Wim Hoff Method: a technique developed by Wim Hof that purportedly combines specific breathing exercises, cold exposure, and meditation to improve physical and mental health. The method aims to strengthen the body's ability to withstand cold, improve respiratory control, and enhance overall well-being. However, it should be cautiously approached, especially by individuals with underlying health conditions.


Fox, S. I., & Rompolski, K. (2022). Human physiology (16th ed.). McGraw-Hill.

Fried, R. (1987). The hyperventilation syndrome: Research and clinical treatment. John Hopkins University Press.

Fried, R., & Grimaldi, J. (1993). The psychology and physiology of breathing. Springer. Khazan, I. (2019). A guide to normal values for biofeedback. In D. Moss & F. Shaffer (Eds.). Physiological recording technology and applications in biofeedback and neurofeedback (pp. 2-6). Association for Applied Psychophysiology and Biofeedback.

Khazan, I. (2019). Biofeedback and mindfulness in everyday life: Practical solutions for improving your health and performance. W. W. Norton & Company.

Khazan, I. Z. (2013). The clinical handbook of biofeedback: A step-by-step guide for training and practice with mindfulness. John Wiley & Sons, Ltd. Meehan, Z. M., & Shaffer, F. (2024). Do longer exhalations increase HRV during slow-paced breathing? Applied Psychophysiology and Biofeedback. Zelano, C., Jiang, H., Zhou, G., Arora, N., Schuele, S., Rosenow, J., & Gottfried, J. A. (2016). Nasal respiration entrains human limbic oscillations and modulates cognitive function. Journal of Neuroscience, 36(49), 12448.

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Apr 15
Rated 5 out of 5 stars.

This is exactly what I am teaching at Conspire Health. Many thanks to Inna and Dr. Peter Litchfield for educating and inspiring me.

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