Ice baths are the recovery modality with the clearest evidence, and the evidence says something more interesting than either camp claims. They work. What they work on is not what most people are training for.
What they reliably do
Reduce perceived soreness and improve how recovered you feel over the following day or two. This shows up consistently, it is not placebo alone, and it matters in real situations: a tournament, a race week, a second session the same day.
The mechanism is a combination of reduced swelling, reduced nerve conduction velocity, and a genuine analgesic effect from cold. All of those are real and all of them are about symptoms.
The part that is usually left out
Cold water immersion soon after resistance training appears to reduce the hypertrophy and strength adaptations from that session. This has been shown repeatedly, and the proposed mechanism is straightforward: the inflammatory and signalling response you are damping down is part of how the muscle is told to adapt.
Which produces an uncomfortable conclusion. If you lift to get bigger or stronger and then sit in an ice bath, you are paying money and discomfort to partially undo the session you just did.
So when should you use one?
Use them when recovery beats adaptation. Multi-day tournaments, two sessions in a day, race weeks, the back half of a competition block. In those situations feeling functional tomorrow is worth more than the marginal adaptation from today.
Avoid them after sessions you want to grow from. Hypertrophy work, heavy strength work, anything in a build phase.
If you want both, separate them in time. Putting hours between the session and the cold is the common recommendation, and the further apart the better.
If you just enjoy it, that is a legitimate reason. Adherence to training matters far more than any of this, and a habit that makes you feel good and keeps you consistent is worth more than a small theoretical adaptation cost.
The protocol, without the theatre
The research clusters around 10 to 15 °C for 10 to 15 minutes. Colder is not better and carries real risk; longer is not better either.
The very short, very cold sessions that dominate social media are not better supported by evidence, they are better supported by being filmable. And cold showers, whatever else they do, are not the same stimulus as immersion.
What actually drives recovery
Sleep and food, by a distance that makes every modality on this page look like rounding. An extra hour of sleep will do more for tomorrow than any ice bath, and it is free.
That is not a reason to never take one. It is a reason to fix the two big things before spending money on the small ones, which is the opposite of how most people approach recovery.
The heat side of the argument is what sauna actually does, and the two together are cold plunge vs sauna.