Holding your breath while entering cold water has gained popularity through figures like Wim Hof, but recent research warns it can be dangerous. Professor Mike Tipton and colleagues at the University of Portsmouth found that breath-holding during cold water immersion triggered cardiac arrhythmias in 63% of healthy volunteers. While often harmless in fit individuals, these irregular heart rhythms can be dangerous – or even fatal – for those with underlying heart conditions.
The risk stems from something called autonomic conflict. Cold water triggers the cold shock response – rapid heart rate, high blood pressure, and gasping – while breath-holding activates the diving reflex, which slows the heart to conserve oxygen. These opposing signals can cause the heart to misfire, leading to arrhythmias.
Breath-holding also causes carbon dioxide (CO₂) to build up in the blood, forming carbonic acid and lowering blood pH – a state known as respiratory acidosis. This increases stress on the heart and can reduce oxygen delivery to vital organs, especially dangerous in cold, high-stress conditions.
To reduce risk, experts advise breathing normally when entering cold water and avoiding extreme breath-control techniques. Entering the water slowly and being aware of your cardiovascular health can help prevent serious complications and allow you to enjoy all the fantastic benefits of cold water immersion, without the risks.
