There's a detail in this conversation I find quietly remarkable. Ryan Duey first encountered cold exposure through the Vice documentary about Wim Hofâmy namesakeâback in 2015. That documentary sent him down a path that led to founding Plunge, one of the most recognized cold immersion companies in the country. And now here we are, years later, talking through mechanisms that were barely articulated when that documentary aired.
The knowledge base has several Ryan Duey conversations. What strikes me across all of them is how his thinking has evolved. His earlier framing was personal and experientialâthe mental resiliency, the consistency, the neural pathway rewriting. This episode goes deeper into mechanism, and that's where things get genuinely interesting.
The core claim here is more specific than it first appears. It isn't simply "cold is good for metabolism." It's that the shiver response is the metabolic trigger. That distinction matters enormously.
When your body shivers, it's recruiting thermogenic mechanismsâbrown adipose tissue activation, increased norepinephrine, the whole cascade. But here's what Duey gets right that many practitioners miss: you don't need extreme temperatures to hit that threshold. Low fifties Fahrenheit can trigger the shiver response. No need to push into the thirties. The benefit lies in reaching the biological threshold, not in maximizing suffering.
This aligns with everything I've seen across the knowledge base. A full episode with Ciaran Flan covers cold exposure and immunity from a different angleâand the same pattern holds there. The body doesn't optimize based on how miserable you were. It optimizes based on whether you crossed the threshold that demanded adaptation.
Recovery timing is where things get genuinely contested. Cold water immersion immediately after strength training blunts the inflammatory signaling that drives hypertrophy. The mechanisms are well-documented. If your primary goal is muscle growth, cold plunging right after your lifts may be working against you.
But here's the nuance Duey navigates carefully: most people aren't competitive bodybuilders optimizing for maximal hypertrophy. For general health, mood regulation, and metabolic function, the tradeoffs look entirely different. The inflammation cold suppresses post-workout is the same inflammation that causes delayed onset soreness, that slows tissue repair in athletes doing repeated daily efforts, that accumulates over weeks of hard training.
The practical answer is simple: for strength adaptations, separate your cold work by at least four hours or move it to the morning before you train. For everything elseâmetabolism, mood, recovery from sportâthe timing is yours to design.
What I find most valuable in Duey's framing is the emphasis on sustainability through ritual. He talks about the consistency of doing something hard daily, and the neural pathway rewriting that follows. I'd put it this way: the habit loop is itself therapeutic.
When you commit to a daily cold practice, you're not only activating brown fat and spiking dopamine. You're building evidence, day by day, that you can approach discomfort deliberately and come through the other side. That's the psychological adaptation that no mechanism study fully capturesâand it compounds in ways the physiology data doesn't measure.
The recommendation is this: find your threshold, not your limit. Water cool enough to trigger the shiver response, two to five minutes, three to five times per week. Build the ritual before you build the intensity. The dose matters less than the consistency. That was true when Wim Hof said it in 2015. It's still true now.