The dose the research used.
Sauna, cold, zone 2, strength, sleep, protein — tracked at the dose the papers actually studied, with the study one click from every number. Claims stay correlational, and say so.
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Four vats. One dye each.
Protocols sit on a dyer's rack: one vessel holds one colour, which protocol you are is how deep the dip, and whether you did it is how much ink. Two things in one vessel can never differ by hue alone — so the week reads at a glance.
Not "science-based". The actual paper, one click away.
In the Laukkanen cohort — 2,315 Finnish men, ~20 years — 4–7 sessions a week was associated with lower cardiovascular and all-cause mortality than one. It is a cohort, so it shows an association, not a cause.
In 122,007 treadmill-tested patients, moving from "low" fitness to "above average" was associated with roughly 70% lower all-cause mortality — the largest effect size in the longevity literature, with no plateau at the top.
Brown fat is the well-established part; "cold makes you tougher" is narrower than the internet says. And the timing rule most people break: no plunge within 4–6 hours after lifting — it appears to blunt hypertrophy signalling.