Before Wim Hof made cold immersion a global practice, English country houses had cold plunge pools.

The practice was common among the landed gentry from the 18th century onwards. Cold water bathing was considered essential to good health, mental clarity and physical resilience. Country houses of a certain standing had plunge pools built into their grounds or basements. Harrogate, in North Yorkshire, built an entire economy around its cold mineral baths.

The science behind the practice was poorly understood at the time. What was understood, through observation, was that regular cold water exposure seemed to produce calmer, more energetic people.

What we now understand is more precise. Cold water immersion activates the sympathetic nervous system, prompting the release of noradrenaline. Regular exposure trains the body's response to stress. Over time, the physiological reaction to cold becomes less extreme. This adaptation appears to extend to other forms of stress.

There is also evidence that cold water immersion reduces inflammation, improves circulation and may support immune function. The research is more developed than it was five years ago, though it remains an active area of study.

The practical application does not require a country house or a specialist clinic. A cold shower for two to three minutes produces a measurable physiological response. A cold bath at 15 degrees Celsius for ten minutes produces a stronger one.

The aristocracy did not have the biology. They had the observation. Sometimes that is sufficient.