[exdsq]

I recently read that a Finnish sauna practically counts as exercise for the cardiovascular system, I assume onsen have a similar benefit.

I'm sure I read somewhere that cold showers can be dangerous for people with per-existing heart conditions too.

I can't cite either right now but they should be easy to find with a Google search.

[Pete_D]

> cold showers can be dangerous for people with per-existing heart conditions

I think cold showers trigger the diving reflex[0] ("most noticeable effects are on the cardiovascular system, which displays ... in humans, heart rhythm irregularities"). I don't have a real source for that, but I tried cold showers a few times and found it impossible to breathe when I had cold water spraying on my face, like I could feel my airway closing involuntarily. Warm/hot water doesn't do that.

[0] https://en.wikipedia.org/wiki/Diving_reflex

[trumbitta2]

I know I have a heart condition (atrial fibrillation) and extreme cold, just like extreme heat, triggers my heart in ways I surely want to avoid at all times.