Asked by: Will Cherrett, Staines

A sudden immersion in cold water increases both your breathing and heart rate to try and generate extra heat to warm you up. This vastly raises the oxygen demands of your body and means that your ability to hold your breath is greatly reduced. An average person, able to go without breathing for 60 seconds, can only manage 20 seconds in water at 10°C. Repeated exposure to cold water can reduce the effect of cold shock, as can various mental techniques to help you remain calm.

The cold shock response only lasts for a few minutes. After that, your heart rate may actually drop below normal, as part of the mammalian diving response. This effect is most pronounced in young children and there are instances of children being successfully revived after spending 30 minutes or more underwater in icy conditions.

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luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.