[Alex3917]

I dunno my theories here have been aging pretty well:

https://news.ycombinator.com/item?id=948637

https://news.ycombinator.com/item?id=2595017

I'm sure there is a placebo aspect, but I wouldn't underwrite the anti-inflammatory component or the sensory stimulation component either.

[WalterSear]

The anti-inflammatory effect of heat shock protein release is well documented and understood. It's the trigger your immune system uses to start recovery after a fever.

As is cryotherapy, as a method of inducing heat shock protein release.