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Comparing the Oxygen Advantage®and Wim Hof methods - by Patrick McKeown

This article was written in response to the hundreds of emails I have received asking the question:

“What are the differences between the breathing techniques in The Oxygen Advantage by Patrick McKeown and Wim Hof’s Becoming the Iceman?”

Defining the two methods:

There are actually many similarities between the breathing exercises in the two techniques. Both methods provide substantial benefits in terms of health, and both produce improvements in sports performance. The breath hold exercises in both disturb homeostasis – the body’s internal balance mechanism – and both stress the body, causing it to make adaptations that may improve immune system function.

Oxygen Advantage® :

  1. Meditation
  2. Functional breathing training
  3. Intermittent hypoxic / hypercapnic training

In the Simulate High Altitude Training exercises from the Oxygen Advantage® the objective is to breathe normally and then perform a breath-hold after an exhalation. This generates an intermittent hypoxic/hypercapnic response, producing low oxygen and high carbon dioxide. During breath-hold exercises, blood oxygen saturation (SaO2) typically drops to about 85 percent. At the same time, arterial carbon dioxide will increase from the normal concentration of 40mmHg to 50mmHg or more.

Wim Hof method:

  1. Meditation
  2. Intermittent hypoxic / hypocapnic training
  3. Cold water immersion

In Wim Hof’s breathing technique, the instruction is to take 30 big breaths through the mouth before holding the breath. This exercise is completed three times in succession. It generates an intermittent hypoxic/hypocapnic response – low oxygen and low carbon dioxide. By the third cycle, blood oxygen saturation can drop to as low as 45 percent and carbon dioxide can fall from the normal concentration of 40mmHg to just 13mmHg. Just to give some context to those figures, an SaO2 of 85 percent represents severe hypoxia and syncope hypoxia (fainting) can occur when SaO2 is less than 60 percent.

These types of breath-hold exercises have proven very effective for respiratory conditions including asthma. A research paper by Kox et al., 2014, exploring the Wim Hof method states: “Healthy volunteers practicing the learned techniques exhibited profound increases in the release of epinephrine, which in turn led to increased production of anti-inflammatory mediators and subsequent dampening of the proinflammatory cytokine response… This study could have important implications for the treatment of a variety of conditions associated with excessive or persistent inflammation, especially autoimmune diseases in which therapies that antagonize proinflammatory cytokines have shown great benefit.”1

There are many positive effects of breath holding following an exhalation. But it is valuable to understand the physiology of hyperventilation and breath holding from a sports performance perspective.

Exploring the Physiology:

Wim Hof explains that taking deep big breaths prior to the breath hold, “fully charges the body by getting rid of carbon dioxide, allowing more oxygen into the body to roam freely and fill up every cell, and increase pH levels”.

In order to shed some light on this explanation, let’s take a look at some simple respiratory science:

Oxygen uptake in the blood and delivery to the cells:

Oxygen (O2) is carried in the blood in two ways:

  1. 98 percent of O2 is carried by proteins called hemoglobin (Hb) inside the red blood cells
  2. 2 percent of O2 is carried dissolved directly in the blood

During normal, healthy breathing, arterial blood is already almost fully saturated with oxygen (between 95 and 99 percent). This means that while ‘big’ breathing such as the 30 large mouth breaths practiced in the Wim Hof method will bring more air into the lungs and increase the partial pressure of O2 in the blood, it will not increase oxygen saturation of the blood.

Breathing ‘hard’:

  • Increases the partial pressure of O2 in the blood
  • Increases the amount of O2 dissolved in the blood (2 percent of oxygen is carried dissolved in the blood)
  • Does not increase saturation of blood with oxygen – 98 percent of O2 is already carried by Hb
  • Lowers carbon dioxide in the blood

Loss of CO2 results in higher blood pH (respiratory alkalosis). Alkalosis increases the affinity of Hb for O2. In other words, it causes the bond between blood and oxygen to become stronger, so less oxygen is delivered to the tissues.

Loss of carbon dioxide also causes the blood vessels to constrict, meaning reduced blood flow throughout the body.

So what effect does breathing ‘hard’ have on oxygen delivery to tissues and organs including the heart and brain? Overall, does it increase or decrease it? To answer this, let’s look at what exactly oxygen saturation is, and how it relates to the proper oxygenation of the muscles and organs.

Oxygen saturation (SaO2) is the percentage of oxygen-carrying red blood cells (hemoglobin molecules containing oxygen) within the blood. During periods of rest, the normal breathing volume for a healthy person is between four and six liters of air per minute. This results in almost complete oxygen saturation of 95 to 99 percent. Because oxygen is continually diffusing from the blood into the cells, 100 percent saturation is not feasible. In fact, an oxygen saturation of 100 percent would suggest that the bond between red blood cells and oxygen molecules is too strong, and that the blood cells were not delivering oxygen to muscles, organs and tissues. The blood must release oxygen, not hold onto it.

The human body actually carries a surplus of oxygen in the blood. This is apparent from the fact that 75 percent of inhaled oxygen is exhaled during rest. Even during physical exercise, when the working muscles and breathing muscles need a much greater supply of oxygen, as much as 25 percent of inhaled oxygen is exhaled. In short, there are no added benefits to be gained by increasing oxygen saturation to 100 percent.

Carbon Dioxide: Not Just Waste Gas

For normal, healthy functioning, the body requires a certain amount of both oxygen and carbon dioxide. It is widely recognized that oxygen is essential to life, but many people are surprised to hear that carbon dioxide is too. CO2 is not just a waste gas. In terms of breathing it works hand in hand with oxygen.

Carbon dioxide is responsible for the release of oxygen from the red blood cells to the tissues and organs. In essence, CO2 acts like a hormone, enabling the release of oxygen in the same way that insulin prompts the release of blood glucose.

When you take 30 big breaths in and out through the mouth, the concentration of carbon dioxide in the lungs and blood significantly reduces. But carbon dioxide is essential for life. It performs a number of vital functions in the human body. These include:

  1. Offloading of oxygen from the blood to be used by the cells

Air enters the lungs during inhalation. Once there, oxygen passes from the lungs to the blood, where it is picked up and carried through the blood vessels by the hemoglobin in the red blood cells. Oxygen-rich blood is pumped throughout the body by the heart, and oxygen is offloaded to the cells for conversion into energy. In order to release oxygen from the blood, hemoglobin requires a catalyst: carbon dioxide.

Physical exercise provides a perfect example of this process. When we move our muscles, the body requires more oxygen to give us energy. This is because muscles are performing at a higher intensity and using more oxygen. During exercise, the body temperature rises and the cells produce more carbon dioxide, allowing extra oxygen to be released by the blood to the muscles and organs. John West, author of Respiratory Physiology, tells us that, “An exercising muscle is hot and generates carbon dioxide, and it benefits from increased unloading of O2 from its capillaries.” The better we can fuel our muscles with oxygen during activity, the longer and harder they (and we) can work.

The concentration of carbon dioxide in the blood is determined by the breathing. The habit of breathing in excess of metabolic requirements causes too much carbon dioxide to be exhaled from the lungs. This causes a reduction of the concentration of CO2 in the blood and cells. When carbon dioxide levels are too low, this inhibits the transfer of oxygen from the blood to muscles and organs, leading to poor body oxygenation.

This function of carbon dioxide was discovered in 1904 by the physiologist and Nobel laureate Christian Bohr. Bohr recognized that CO2 affects the release of oxygen from the blood to tissues and organs. When there is an increased pressure of carbon dioxide in the blood, pH drops, and oxygen is released more readily. This is called the Bohr Effect. Conversely, when carbon dioxide levels are low, hemoglobin molecules are less able to release oxygen from the blood. The way you breathe determines the amount of carbon dioxide present in your blood and how well oxygenated your body is.

The science described by the Bohr Effect indicates that taking 30 large mouth breaths will lower the concentration of carbon dioxide in the blood and limit the release of oxygen from the blood to the cells.

  1. The dilation of the smooth muscle in the walls of blood vessels

Breathing too much air can cause reduced blood flow to tissues and organs including the heart and brain. For the vast majority of people, 30 big breaths is enough to reduce blood circulation throughout the body, including the brain, causing dizziness and light-headedness. This will be experienced by many people who hyperventilate prior to breath hold techniques.

Blood flow to the brain reduces proportionately to reductions in carbon dioxide2. A study published in the American Journal of Psychiatry, which assessed arterial constriction induced by excessive breathing, found that the diameter of blood vessels reduced in some individuals by as much as 50 percent3. Based on the formula [pi] r squared (A = πr2), which measures the area of a circle, blood flow decreases by a factor of four. This shows you how seriously over-breathing can affect your blood flow.

  1. The Regulation of Blood pH

In addition to determining how much oxygen is released into the tissues and cells, carbon dioxide plays a central role in regulating the pH of the bloodstream – the acidity or alkalinity of the blood. Normal pH in the blood is 7.365. This level must remain within a tightly defined range or the body is forced to compensate. The homeostatic maintenance of normal blood pH is vital to our survival. If the pH is too acidic and drops below 6.8, or too alkaline and rises above 7.8, the result can be fatal4. This is because the pH of the blood directly affects the function of the internal organs and metabolism.

Respiratory alkalosis can prompt changes in the nervous system and in physical and psychological states. It can cause symptoms including breathlessness, chest pain, headaches, fatigue, dizziness and light sensitivity, and lead to the development of myofascial trigger points5. It has a significant negative effect on the musculoskeletal system, is detrimental for health and performance.

Scientific evidence clearly shows that carbon dioxide is an essential element. It regulates the breathing, optimizes blood flow and releases oxygen to the muscles. But it is also vital for maintaining correct pH levels. It affects nearly every aspect of how our body functions. In short; the body’s relationship with carbon dioxide determines how healthy we can be.

Better breathing allows carbon dioxide to do its job. It ensures that all the systems within the work together in harmony, allowing us to achieve our maximum potential in sporting performance, endurance and strength.

Why does Breath Hold Time Improve Following 30 Large Breaths?

In an interview with Joe Rogan, Wim Hof explains that, after 30 big breaths: “At a certain point you are so fully charged, pH go to a very high level, you are able to stay without air in the lungs for minutes. You will hold your breathing for much longer than normal because we changed your body chemistry. Carbon dioxide went out, O2 went up, filled up all the cells and the pH levels go up.”

Breath-hold time will increase if you take 30 big breaths immediately prior to breath holding. However, this is primarily due to the fact that the stimulus to breathe is driven by carbon dioxide, not oxygen. The body breathes to get rid of excess carbon dioxide via the lungs. When CO2 levels are too low, this respiratory stimulus is repressed.

This is why, when you take 30 big breaths, depleting your blood carbon dioxide, it becomes possible to hold the breath for longer periods of time. In fact, you will be able to sustain the breath hold until carbon dioxide levels rise again and prompt the respiratory center in the brain to resume breathing. For this reason, you must never perform hyperventilation prior to entering water. With the signal to breathe compromised, you will not feel the need to breathe, even when your body needs air. This can result in oxygen levels dropping too low, leading to underwater blackout and, potentially, drowning.

Negative Effects of Mouth Breathing

Nose breathing is healthy breathing. Dr. Maurice Cottle, who founded the American Rhinologic Society in 1954, stated that the nose performs at least thirty functions. All of these are important in supporting the lungs, heart and other organs6. Breathing through the nose improves arterial oxygen uptake and delivery, enhances ventilation perfusion (gas exchange in the lungs) and acts as a defense against airway constriction including exercise-induced asthma. It also prevents cold, dry, unfiltered air from entering the lungs, harnesses nasal nitric oxide, which has antiviral and antibacterial properties, engages the diaphragm and slows the respiratory rate, activating the body’s rest and digest functions.

Mouth breathing, on the other hand, is considered an abnormal and inefficient way to breathe. It may induce functional, postural, developmental and biomechanical imbalances – all of which can be detrimental to health and to sports performance7.

One of the main drawbacks to breathing through the mouth is that it causes upper chest breathing and less movement of the diaphragm8. The diaphragm is the main breathing muscle, but it is surprisingly common for poor breathing habits to reduce its efficacy. Breathing with the diaphragm is naturally beneficial. It activates the body’s relaxation response, supports the core, stabilizes the spine9, impacts pain perception and enables better transfer of oxygen from the lungs to the blood (ventilation/perfusion) 10.

Diaphragmatic breathing also helps to prevent the build-up of free radicals in the body. Free radicals are molecules created during the metabolism of oxygen. When excessive free radicals are present, the body suffers, because these molecules attack other cells and damage tissues. In one study, researchers found that when athletes spent one hour relaxing and practicing diaphragmatic breathing, they experienced reduced heart rate, increased insulin, reduced glycaemia, higher antioxidant levels and lower free radical production11. Alongside its benefits in terms of relaxed breathing, diaphragmatic breathing may facilitate a lower level of oxidative stress, which the researchers concluded could protect athletes from long-term adverse effects of free radicals


My experience is that dysfunctional breathing such as mouth breathing, upper-chest breathing and sleep-disordered breathing is incredibly common, both in the general population and in highly trained athletes. This is backed up by significant scientific evidence. My advice for athletes wanting to enhance performance and potential is always to restore functional, nasal breathing during wakefulness and sleep and to work to achieve a BOLT score of 40 seconds. With a good understanding of functional breathing, many people like to explore more extreme breathing methods. But until you have an experiential understanding of the role of CO2 in respiratory biochemistry, and the biomechanics and cadence of breath, I would always recommend the practice of light, slow and deep breathing over the technique of 30 big breaths. While it can be tempting for anyone with a competitive, perfectionist nature to approach any new learning from an extreme perspective, the breath can definitely be most powerful when at its most gentle.

Learn the Oxygen Advantage® technique


  1. Kox, Matthijs, Lucas T. van Eijk, Jelle Zwaag, Joanne van den Wildenberg, Fred CGJ Sweep, Johannes G. van der Hoeven, and Peter Pickkers. “Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans.” Proceedings of the National Academy of Sciences111, no. 20 (2014): 7379-7384.
  2. Magarian, Gregory J., D. A. Middaugh, and D. H. Linz. “Hyperventilation syndrome: a diagnosis begging for recognition.” Western Journal of Medicine138, no. 5 (1983): 733.
  3. Gibbs, Daniel M. “Hyperventilation-induced cerebral ischemia in panic disorder and effect of nimodipine.” The American journal of psychiatry (1992).
  4. Casiday Rachel, Frey Regina. Blood, Sweat, and Buffers: pH Regulation During Exercise Acid-Base Equilibria Experiment. http://www.chemistry.wustl.edu/~edudev/LabTutorials/Buffer/Buffer.html (accessed 20th August 2012).
  5. Bradley, Helen, and Joseph Dr Esformes. “Breathing pattern disorders and functional movement.” International journal of sports physical therapy 9, no. 1 (2014): 28.
  6. Ley, Ronald, and Beverly H. Timmons, eds. Behavioral and psychological approaches to breathing disorders. Springer Science & Business Media, 2013.
  7. Trevisan, Maria Elaine, Jalusa Boufleur, Juliana Corrêa Soares, Carlos Jesus Pereira Haygert, Lilian Gerdi Kittel Ries, and Eliane Castilhos Rodrigues Corrêa. “Diaphragmatic amplitude and accessory inspiratory muscle activity in nasal and mouth-breathing adults: a cross-sectional study.” Journal of Electromyography and Kinesiology25, no. 3 (2015): 463-468.
  8. Key, Josephine. “‘The core’: understanding it, and retraining its dysfunction.” Journal of bodywork and movement therapies17, no. 4 (2013): 541-559.
  9. Sánchez Crespo, Alejandro, Jenny Hallberg, Jon O. Lundberg, Sten GE Lindahl, Hans Jacobsson, Eddie Weitzberg, and Sven Nyrén. “Nasal nitric oxide and regulation of human pulmonary blood flow in the upright position.” Journal of applied physiology108, no. 1 (2010): 181-188.
  10. Martarelli, Daniele, Mario Cocchioni, Stefania Scuri, and Pierluigi Pompei. “Diaphragmatic breathing reduces exercise-induced oxidative stress.” Evidence-Based Complementary and Alternative Medicine2011 (2011).