Wim Hof breathing dampened the response to endotoxin, and cold training helped only when added to it
The 2022 Psychosomatic Medicine pilot study came from the team behind the 2014 Wim Hof trial. It split the method into its parts and tested each one against injected endotoxin.
The paper
The Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot Study
Zwaag J, Naaktgeboren R, van Herwaarden AE, Pickkers P, et al.. Psychosomatic Medicine, 2022;84(4):457-467.
See the study at a glance
- Design
- Two randomized pilot studies
- People
- 88 men
- Who they were
- Healthy men: 40 in the first study and 48 in the second.
- What they did
- The first study compared short and extensive breathing training taught by Hof or by an independent trainer. The second randomly assigned men to cold exposure training, breathing training, both or neither, and then gave them 2 ng/kg of bacterial endotoxin.
- How long
- Training, then one endotoxin test day
These numbers came out of it
Cold alone
Men who did only the cold training responded to endotoxin much like untrained men (P = 0.77).
Breathing alone
Breathing training by itself changed the response to endotoxin (P = 0.002).
Both
Adding cold training made the breathing effect stronger (P = 0.02), and the combination had the strongest effect.
The researchers did this
After the 2014 trial, the same research group set out to test the parts of the Wim Hof Method one at a time.Source 1 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗Source 2 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ In a first study of 40 healthy men, short and extensive breathing training both raised adrenaline, and it didn't matter which trainer taught it.
The second study randomly assigned 48 healthy men to cold exposure training, breathing training, both or neither, and then injected all of them with 2 ng/kg of bacterial endotoxin.Source 1 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗ Breathing alone changed the inflammatory response (P = 0.002), and cold training on top of it made that effect stronger (P = 0.02). Cold training by itself produced no meaningful change (P = 0.77).
Men who did both had the strongest effect overall. That fits the 2014 authors' conclusion that the breathing drove most of what they saw.Source 2 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗Source 1 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗
The study can't tell you these things
- It was a pilot study, and the four-group experiment had only 48 men.
- Only men took part.
- Endotoxin is a lab model of inflammation, so the study says nothing direct about infections.
People quote it like this
Anyone citing the Wim Hof immune results for cold plunges alone runs into this study. Cold training by itself didn't change the response to endotoxin.Source 1 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗
We cited these sources
- 01Zwaag J, Naaktgeboren R, van Herwaarden AE, Pickkers P, Kox M. The Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot Study. Psychosomatic Medicine. 2022;84(4):457-467. doi:10.1097/PSY.0000000000001065 PMID 35213875
- 02Kox M, van Eijk LT, Zwaag J, van den Wildenberg J, Sweep FCGJ, van der Hoeven JG, et al.. Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans. Proceedings of the National Academy of Sciences. 2014;111(20):7379-7384. doi:10.1073/pnas.1322174111 PMID 24799686