31/10/2026
Excellent thoughts from Barbell Medicine
Andrew Huberman’s new book gives a few reasons to cold plunge, but here’s the one with a number attached. After you get out, he writes, “the sharp increase in adrenaline, norepinephrine, and cortisol we just triggered also sets in motion a dramatic and prolonged increase in dopamine.” So I pulled the study that dopamine number comes from. Three problems. The subjects sat in cold water for a full hour, not the one to three minutes the book prescribes. Of the three hormones he says spike, only one did: norepinephrine. Adrenaline didn’t move, and cortisol went down. The dopamine did climb about 250%, but who cares? The study never looked at mood, or at anything else you’d actually want from a cold plunge. The book makes this same kind of mistake over and over. Let’s talk about it.
The mistake is really two in one. The first is to overhype a mechanism that isn’t even real. Somebody tells you cold water spikes cortisol, and it drops. Or that depression comes from a chemical imbalance, too little serotonin, which is what the pills were supposedly fixing. While the meds can help, the mechanism is wrong: there’s no good evidence depression is caused by low serotonin at all. And for decades people blamed sore muscles the day after training on lactic acid, when the lactic acid is gone within about an hour and we still don’t really know what causes the soreness. The story gets repeated until it sounds like fact, and it travels quickly because a mechanism that “makes sense” is easy to sell.
The second version is when the mechanism is real, but exploiting it doesn’t change the outcome. After a heart attack for example, extra heartbeats predict sudden death. For years we gave drugs to stop the extra beats and the drugs did a great job. Then somebody studied the use of these drugs in this exact situation and the treated group died at a much higher rate, enough that they stopped the study early. We also used to stent clogged arteries in the heart for those with stable chest pain, until a trial with a fake surgery arm found the real stents relieved the pain no better than the sham. Beta carotene was supposed to lower cancer in smokers because as an anti-oxidant, it mops up the kind of damage that causes it. When tested, the studies found that the supplement group got 18% more lung cancer.
All of those made perfect sense on paper, which is exactly why you run the study instead of trusting the paper. With the cold plunge for example, the 250% was dopamine in the blood, which isn’t dopamine doing anything in your brain. It’s just another mechanism where the outcomes don’t follow. A recent review pooled 61 trials of recovery methods and found cold water no better than doing nothing for soreness, strength, or muscle damage. And if you do it right after lifting, it may reduce strength and muscle gains. This seems like a bad trade off for a bump in dopamine of unknown significance.
The best use case for a cold plunge is heat stress. If your core temperature is climbing faster than your body can shed it, from working outside, training in the heat, or from heat exhaustion, then cold water is the fastest way to cool a person down. I should point out that this is not really a fitness claim, it’s the go-to treatment for heat stroke. Short of that, you’re just a warm person getting into cold water. If you want to jump in a cold pool because you’re hot, go for it.
The same pattern runs through much of the other protocols we reviewed. We put about a dozen of these on trial for our Halloween episode, morning sunlight, continuous glucose monitors, saunas, readiness scores, a variety of supplements, and we did the same thing to Huberman’s book. Most are a confident mechanism with no outcome data, a couple are bassackwards, and nearly all of them come with a subscription. It’s free, linked in the first comment.
I think the underlying idea here is that you can micromanage your own physiology better than your body does. You can’t, fortunately. Your body maintains your blood pressure, electrolyte and volume status, pH balance, and more inside tight ranges that keep you alive and functioning. If you were in charge of all that, you’d probably mess it up because it’s far more complicated than a single mechanism.
For most protocols, the stakes are limited to time, money, and your attention. For others, they could cost you a lot more. If you really want to live better, make sure you choose wisely.
What optimization protocol do you think is worthwhile?
