Contrast therapy: what the trials support, and what they do not

Contrast therapy is the most requested and least evidenced thing we offer. We offer it anyway, supervised, and we are careful about what we say it does.

Sauna: the better half of the evidence

The Finnish cohort data is the strongest material available. In a prospective cohort of over two thousand middle-aged men followed for a median of twenty years, frequency of sauna bathing was inversely associated with cardiovascular and all-cause mortality, with an apparent dose relationship. It is observational. Sauna frequency correlates with leisure time, income and baseline health, and the authors say so.

Mechanistically the story is plausible — repeated heat exposure produces cardiovascular responses that resemble moderate exercise. Plausibility is not proof, and the outcome trial has not been done.

Cold water: thinner still

Cold immersion has short-term data on perceived recovery and delayed-onset muscle soreness, with effect sizes that are small and inconsistently replicated. There is reasonable evidence that cold immediately after resistance training blunts hypertrophy adaptation, which is why we schedule it away from strength sessions rather than after them.

Claims about metabolic rate, brown fat and immune function in humans rest on very small studies. We do not repeat them.

Why we still run the protocol

Because people will do it regardless, and doing it supervised, at controlled temperatures, with a blood pressure check first, is materially safer than doing it alone in a barrel. That is the honest justification. It is not that we think it extends life.