8 min.
There's a method that lets you actively train your immune system — studied by Radboud University Nijmegen. No pills, no expensive supplements, no special diets. Just your breath and cold.
This isn't wishful thinking. It's the result of a study by Radboud University Nijmegen that shook the scientific world in 2014 — and has been confirmed repeatedly ever since.
Your immune system is not fixed. It is not set in stone. It responds to training. And once you know how to train it, you change your entire health profile.
← Part 1 of this series: Why burnout is a nervous system problemThe vicious cycle: why more and more people struggle with a weak immune system
Two to three colds a year. Recurring minor infections. After every major stretch of stress: a week flat on your back. An immune system that just doesn't work the way it used to.
That's not bad luck. That's biology under modern conditions.
Chronic stress — and as we saw in the first article in this series, most of us are living with it permanently — directly suppresses the immune system. Cortisol, the stress hormone, is immunosuppressive. It dampens T-cell activity, reduces antibody production, and raises inflammatory markers in the body.
The result is a paradoxical state: you're chronically stressed and chronically inflamed. Your immune system is simultaneously overloaded and underactive. It reacts to the wrong things — and no longer properly to the right ones.
- More infections — colds, flu, minor bugs that simply didn't happen before
- Slower recovery — what used to take two days now drags on for two weeks
- Chronic inflammation — joints, skin, digestion: things that just won't fully heal
- Energy deficit — because your body is constantly fighting itself
The good news: this is not your fate. It's a trainable condition.
The key misconception: Most people think strengthening the immune system means: more vitamin C, more sleep, less stress. That's true — but it doesn't go far enough. Your immune system has an active training component that almost nobody uses.
The Radboud study: how Wim Hof stunned the scientific world
In 2014, researchers at Radboud University Nijmegen published a study that broke the prevailing scientific dogma. The dogma: the autonomic nervous system cannot be consciously controlled. It runs automatically — and so does the immune response.
Wim Hof had been claiming the opposite for years. Nobody believed him.
The study tested two groups: a control group with no training, and a group that Wim Hof had trained in his breathing technique, cold exposure, and meditation.
Then the researchers injected a bacterial endotoxin into both groups — a cell wall component (lipopolysaccharide, LPS) from E. coli that normally triggers a strong immune reaction (fever, chills, nausea).
The result was unambiguous:
The WHM group remained almost symptom-free despite the same injection. Their bodies had actively dampened the inflammatory response — through conscious control of the autonomic nervous system.
That wasn't a placebo. That was measurable physiology.
"With this study we have shown that it is possible to consciously influence the autonomic nervous system and thereby modulate inflammatory responses."
— Prof. Peter Pickkers, Radboud University Nijmegen
How WHM breathing and cold concretely train your immune system
Two mechanisms work together here:
Mechanism 1: Breathing technique and adrenaline
The WHM breathing exercises trigger a controlled release of adrenaline — the Radboud study makes this clear. Adrenaline (epinephrine) in short, controlled doses is strongly anti-inflammatory: it inhibits the production of cytokines (inflammatory messengers) and down-regulates the immune response. According to the follow-up study (Zwaag et al., 2018), the breathing technique is the decisive active factor — even more important than cold exposure alone.
The paradox: you're training your body through a controlled "stress response" so that it reacts less inflammatorily in everyday life. Like a muscle that grows stronger through load.
Mechanism 2: Cold exposure and immune activation
Cold — whether a cold shower or an ice bath — triggers a further biochemical cascade:
- Activation of brown adipose tissue (thermogenic response)
- Improved blood circulation and cardiovascular conditioning
- A powerful stimulus that acclimatises body and mind to controlled stress
Regular cold exposure is a valuable part of the method and supports the body on multiple levels — even though the primary effect on inflammation regulation clearly lies with the breathing technique.
What course participants report after 4 weeks
The science is compelling. But what does it feel like in practice?
I've been guiding people through WHM courses for years — private individuals as well as corporate groups (Aareal Bank, MVZ Stuttgart). Here's what I regularly hear after 4 weeks:
"For the past two years I'd been laid flat for at least a week every cold season. This winter: nothing. Not a single cold. All my colleagues were sick."
— Participant, WHM corporate course 2025
"My chronic back pain — which I had attributed to inflammation — noticeably improved after six weeks of WHM. My doctor was surprised."
— Participant, WHM beginner course Rodgau
These aren't exceptions. It's a pattern I observe again and again. Because the mechanisms are real.
→ Curious what a WHM course would look like for you? All course formats are hereHow you can start today — and what the next step is
Your immune system responds quickly to the right training. First measurable changes — more energy, less fatigue after infections — often show up after just 2–3 weeks of regular practice.
But there's one aspect I often see underestimated: the mental component. Most people don't fail at the breathing technique. They fail in their heads. The fear of cold. The feeling of losing control.
And that's exactly the topic of the third article in this series.
Next step: Your body is trainable — we've established that. But what about your mind? What happens when fear and loss of control are the real blocker? The final article in this series has the answer.
