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Glossary

Haenyeo

Defined in topic 25

Women divers of Jeju, Korea. Before wetsuits arrived in 1977 their winter metabolic rate ran about 35% above the standard; within a few years of covering up, the adaptation was gone.

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Chapters of the book that mention Haenyeo

Where this comes from

In the reference topic that owns this term

Reference topic 25, The Thermoneutral Trap, states the mismatch as a card: what the system evolved to expect, what it gets instead, and what happens in the gap.

Mismatch card

What it expects

A day and a year that leave the thermoneutral band: cold mornings, hot afternoons, cooling nights.

What it gets

18°C to 25°C indoors, all year, for about 87% of the time.

What happens in the gap

Cold-recruited tissue and whole-body acclimatization fade within a few years of the signal stopping, as the haenyeo showed, though the metabolic cost is small.

The full card, and the topic behind it

What that chapter recommends

3 of the 4 graded recommendations in Reference topic 25, strongest evidence first. How the grades work.

  1. Finish your shower cold for 30 to 90 seconds

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    All three durations cut self-reported sickness absence equally in the one large trial. In open water, habituate and never swim alone (●○○).

    Read it in full

  2. Sauna: if you enjoy it, make it regular

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Practice in the Finnish cohort was about 79°C for about 14 minutes, four to seven times a week. Safety: no alcohol, involved in half of Finnish sauna deaths.

    Read it in full

  3. Hot baths, with Japanese caution

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Near-daily tub bathing tracked with lower cardiovascular risk in 30,076 Japanese adults, and a 40°C to 42.5°C bath one to two hours before bed shortens the time it takes to fall asleep.

    Read it in full

Related terms

The argument behind this term, its studies and its notes are in Reference topic 25 of the reference library. The book gives the practical version. Get the book.