Well you're the man to know how research on all this is still in its infancy, which is sad and odd, it means we kinda know less about our bodies than we know about the stars.

I always like to think about how our ancestors used to live. People used to recommend running every morning, and now they say that's either pretty much useless or even bad for you (for your knees for instance). I knew that was the case beforehand because running didn't make sense from an evolutionary perspective. People walk. They might even walk for long distances. Very long, sometimes. But they don't run unless it's for short bursts. Energy is like gold in nature and people do everything to preserve it. The body stores fat like it's gonna wait a year till its next meal but builds muscle like children eat broccoli: gruelingly. So it's kinda an odd sight, our fitness culture, of moving about like dancing, running on treadmills, not doing any actual work, none that a single doughnut won't undo. Some kind of manual labor like lifting stuff seems, from this perspective, like the most natural and healthy exercise.

Anyway, this comment is all over the place and I haven't really done the research to be perfectly informed!