🧊 Biohacking report

Cold, Heat & Hormesis

Ice baths and sauna are trending, but the science has important nuances — including when cold can work against you if you want muscle.

Laukkanen et al. 2015Søberg et al. 2021Roberts et al. 2015Šrámek et al. 2000
4–7×
Sauna
week, 15–20 min
~11
Cold
min/week total
−40%
Mortality
frequent sauna
+250%
Dopamine
after cold
📚 Scientific references
  • Laukkanen, T., et al. (2015). "Association between sauna bathing and fatal cardiovascular and all-cause mortality events." JAMA Internal Medicine, 175(4), 542–548.
  • Søberg, S., et al. (2021). "Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men." Cell Reports Medicine, 2(10).
  • Roberts, L.A., et al. (2015). "Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training." Journal of Physiology, 593(18), 4285–4301.
  • Šrámek, P., et al. (2000). "Human physiological responses to immersion into water of different temperatures." European Journal of Applied Physiology, 81(5), 436–442.
  • Patrick, R.P., Johnson, T.L. (2021). "Sauna use as a lifestyle practice to extend healthspan." Experimental Gerontology, 154, 111509.

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