Wouldn't believe it if I hadn't seen it myself

[Geek King]

And is it just me, or does anyone else notice that crazy people seem to be unnaturally strong? It amazes me how, say, a 90-pound female patient with unmedicated schizophrenia can somehow throw three 200-pound guards off her.

Nope. See, non-crazies (maybe just less-crazy?) pay attention to this thing your body does when you push it too far. We call it pain. The far-gone crazy get themselves so worked up that they ignore the pain, and can push their bodies past boundries the rest of us know better than to cross. It is the same sort of thing when you hear about the 5'2", 120 pound grandpa lifting a car off of someone. The brain can shut that down if the stimulus is great enough, but you pay for it later.