Things I did not know two hours ago:
1) Although they look and feel solid and outweigh their average user, most exercise machines are actually made of hollow bars and tubes of metal. They're pretty lightweight, and ordinarily that's a good thing. Ordinarily.
2) While aware that repeatedly stressing the same portion of anything will eventually deform or break it, I had no idea that the amount of force put out by the leg of an exercising human over a period of maybe a month was capable of creating sufficient stress.
3) Hollow metal hitting a concrete floor sounds like a gunshot when you're standing on top of the metal in question. It's also loud enough to be heard on every floor of a two-story building with a basement, although the basement's construction means it generally "eats" sound.
4) It cannot put a dent in cement - however, it also doesn't absorb the shock of more or less stomping full force on said cement. In other words, folks, it hurts when you land on it barefoot, and if you aren't hanging on you're going to fall over sideways.
I'm fine, aside from a really jumpy heart rhythm and a sore heel, but the machine's totaled. Good thing it was free. It's going out to the curb as soon as we figure out how to muscle it up the stairs.
And here I was, thinking the most exciting part of my day was locating some worthwhile stuff at a few garage sales.