Apart from exposure to cold, the core element of the Wim Hof Method is a breathing technique, which alternates between hyperventilation and hypoventilation (apparently similar to Tummo meditation). It consists of repeating the following steps for 3-4 times:
- Hyperventilation for 30 deep, strong breaths.
- Breath hold after an exhalation for as long as possible.
- Inhalation followed by another breath hold for ~10 seconds.
The exercise seems to have a profound effect on human physiology, which has been discovered in Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans. The focus of the experiment was to study the immune response after administration of an endotoxin while performing the breathing exercise. The study revealed the following physiological reactions (see also videos in the supplementary material):
- Increases epinephrine levels.
- Suppresses immune response, i.e., decreased pro-inflammatory mediators (TNF-α, IL-6, IL-8) and increased anti-inflammatory mediators (IL-10).
- Blood pH: Increases from ~7.4 to over ~7.7 during hyperventilation (respiratory alkalosis); falls back to ~ baseline during breath retention.
- Oxygen saturation: At 100% during hyperventilation; temporarily drops to ~50% during the breath hold.
- Arterial pCO2: Decreases from a baseline of ~4.5 kPa to below 2 kPa during hyperventilation. The breath hold recovers pCO2 but not fully to baseline level, which is why the minimum pCO2 seems to decrease with each hyperventilation.
- Arterial pO2: Increases from a baseline of ~16.5 to kPa over 22 kPa during hyperventilation. During the breath hold pO2 can fall below 4 kPa, and the minimum seems to become lower with each repetition. pO2 stays slightly elevated post exercise.
Looking at these physiologic reactions, I'm wondering how performing this exercise on a daily basis would affect the development of cancer? I am a scientist, but not in the field of medicine or health, so it is difficult to make sense these effects. Naively, I would think that some of the reactions like the more alkaline blood pH and a more efficient immune system should be beneficial for preventing cancer. Also, a 2017 study has found positive effects of breath training on respiratory cancer. On the other hand, the exercise involves states of low oxygenation during both:
- Hyperventilation: As a result of the low carbon dioxide levels, haemoglobin binds oxygen (Bohr effect), leading to reduced tissue oxygenation.
- Breath hold: The low oxygen saturation and arterial pO2 probably means that the body is in a temporary state of generalized hypoxia at the end of the breath hold.
A quick research on the connection between oxygenation/hypoxia and cancer seems to indicate that hypoxia is something that should be avoided by all means, because it promotes malignant progression and metastasis, and increases resistance to therapy and mortality (Wikipedia, 2004 article, 2007 article, 2016 article).
Is it possible for an experienced health scientist to put these observations into perspective? I.e., would you recommend (or advise against) a cancer-prone person to do such an exercise from a purely theoretical point of view?