Dr. Stacy Sims is making a specific argument here, and it's worth taking seriously: cold exposure isn't wrong for women, but the temperature thresholds matter enormously. Ice baths that men routinely use — water that's truly icy — create such a severe vasoconstrictive response in women that the therapeutic signal gets lost in the survival noise. Around 55-56°F, you still get the dopamine cascade, the inflammatory dampening, the metabolic adaptations. You just don't get the panic.
And for most recovery goals, she's saying heat — specifically a traditional Finnish sauna at 185-210°F — delivers more consistently across more outcomes for more women. That's a strong claim. Let's see how it holds up.
Rhonda Patrick has covered the sauna data extensively, and the cardiovascular numbers are unambiguous — four to seven sessions per week correlates with a 50% reduction in cardiovascular mortality in the Finnish longitudinal studies. The heat shock protein activation, the insulin sensitivity improvements, the growth hormone response — these show up repeatedly across the literature, for men and women alike.
What Sims adds is the female-specific layer. The hypothalamus connection is particularly compelling. Women navigating perimenopause and menopause are dealing with a hypothalamus that's already dysregulated — it's why hot flashes happen. Sauna use sends a controlled, deliberate thermal signal to that same system, and over time it recalibrates. You're essentially training the thermostat by pushing it intentionally rather than waiting for it to misfire.
The post-resistance training debate is where things get nuanced. The sports science community broadly agrees that cold immersion within the first few hours after lifting blunts hypertrophy signaling — you're interrupting the inflammatory cascade that drives muscle adaptation. Sims puts the window at eight hours, which is conservative but defensible. Sauna after lifting, by contrast, compounds the cardiovascular adaptation without interfering with strength gains. That's a meaningful distinction for anyone training seriously.
The disagreement lies in how universal the temperature thresholds really are. Individual variation in cold tolerance is enormous, and some researchers would push back on drawing bright lines around 55-56°F. But as a practical default for women new to cold exposure, it's a reasonable starting point.
If you're a woman building a recovery protocol: lead with sauna after resistance training, especially two to three sessions weekly at proper Finnish temperatures. For cold, start at 55-56°F and resist the urge to go colder just because colder sounds more rigorous. The therapeutic dose is already there at that temperature. More cold isn't more benefit — it's more constriction, more cortisol, more system shutdown.
Sims mentions endometriosis almost in passing, but it's worth pausing on. Cold exposure dampening the inflammatory drivers of endometriosis is a clinically significant application — not just recovery optimization. It suggests that for certain conditions, precise cold at the right temperature is genuinely therapeutic, while extreme cold might actually worsen the inflammatory picture. The same mechanism, the same modality, produces different outcomes depending entirely on dosage. That's the lesson that applies everywhere in contrast therapy: the signal is in the threshold, not the extremity.