Athletes already know the answer from years of cultural knowledge, research, and firsthand experience. No, it doesn't make your cardio fitness meaningfully better. If you did sauna training for years and then tried to ramp up for a marathon, you'd be hopelessly out of shape.

Endurance athletes obsessively track VO2 max, basically your body's ability to consume oxygen during workouts, and it certainly doesn't improve with sauna training.

It's like asking "if you only did puzzles, would you be smarter?" Well, in a way, yes, but if you actually want to compete with someone with a good education you have to read.

Same with physical exercise. It puts a lot of different stresses on your body that saunas don't. The question isn't "do saunas make you physically fit," because they don't. The question is "for people who don't want to exercise, does sauna training alone meaningfully extend your healthspan?" I'm guessing the answer is "a little but not enough," but I'm not sure.

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monkpit 5 hours ago | parent [-]

You’ve honed in specifically on VO2 but what about cardio health in general? Like light treadmill, not like a demanding marathon.

	▲	asdfman123 4 hours ago \| parent \| next [-]
		Cardio of course is short for "cardiovascular system," which consists of a whole lot of moving parts. Saunas improve some parts of it but certainly not all of it. Will fixing up your radiator fix your car? Maybe, if the radiator was the problem, but there's a lot of other stuff inside a car to work on, too. Your body evolved under the expectation that it would be stressed in numerous different ways, but those stressors can all be avoided in the modern era. If you want to most reliably recreate those stresses you need to do cardio and resistance training.
	▲	nradov 4 hours ago \| parent \| prev [-]
		A light treadmill session won't do much to improve your cardiovascular system health either. I mean it's better than nothing but don't expect too much.