The Science of Cold
Cold is a drug
Cold water immersion triggers a 200-300% spike in norepinephrine — a neurotransmitter that boosts focus, mood, and energy for hours. It also activates brown fat and reduces inflammation.
Cold exposure vs other interventions
Compare cold therapy to common alternatives.
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Brown fat: your secret heater
Cold exposure activates brown adipose tissue (BAT), which burns calories to generate heat. Regular cold exposure increases BAT volume, improving metabolism and insulin sensitivity.
Estimate the dopamine boost
How long does the dopamine elevation from cold exposure last?
This step is interactive — open the Thier app to try it.
Cold AFTER training blunts hypertrophy
If you're trying to build muscle, save the ice bath for non-training days or at least 4-6h after lifting. Multiple studies (Roberts et al.; Fyfe et al.) show cold immersion within 1h of resistance training reduces hypertrophy signalling and long-term muscle gains by 10-25%. Cold's anti-inflammatory action is great for everyday recovery — but inflammation IS the muscle-growth signal.
Key Takeaway
Cold exposure is one of the most powerful free biohacks: 250% norepinephrine boost, brown fat activation, and sustained dopamine elevation for hours.