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The 11-minute rule, re-read

Xavi Donobedian 1 min read

The internet's favourite cold and heat dose came from a description of what one group of swimmers did. What the study actually showed.

Ladder into icy harbour water with a sauna hut behind

Eleven minutes of cold and 57 minutes of heat a week. You have probably seen the numbers. Here is where they came from.

The study

Dr Susanna Søberg and colleagues at the University of Copenhagen published the work in Cell Reports Medicine in 2021. They studied experienced young male winter swimmers in Copenhagen who combined cold water dips with sauna two to three times a week, and compared them with men who did neither.

What they found

  • The winter swimmers had a lower core body temperature.
  • When cooled, they produced more heat than the control group.
  • Brown fat glucose uptake during cooling rose to a similar degree in both groups.
  • At a comfortable temperature, the swimmers showed no brown fat activity.

One of the researchers said they had expected the swimmers to have more brown fat, and instead found better temperature regulation.

Where the 11 and 57 come from

Those figures describe roughly how much cold and heat this group of swimmers had each week. They were not tested against other doses. The study was not designed to find a minimum or an optimum.

What we take from it

  • Regular, short cold exposure plus sauna is associated with a body that handles temperature differently. That is interesting.
  • The "11 minutes" figure is a reasonable starting point, not a prescription.
  • It came from a small group of young men. Older adults and women may respond differently.

With an N-03 or N-02 and a Kube, a few short cold sessions and a few sauna sessions a week is a sensible, sustainable pattern. Build it at a pace that suits you.

Free: The Norge Longevity Guide. Heat, cold and light after 50, with the evidence and the safety rules in one place. Get the guide.

Sources

  1. Søberg et al., Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men, Cell Reports Medicine, 2021
  2. ScienceDaily summary

This article is general information, not medical advice. If you have a heart condition, low blood pressure or are pregnant, speak with your GP before using heat or cold.

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