last weekend, I was carrying an 80-pound speaker and didn't see a 6-inch step down. Instantly, my body dropped. In my head, I had a quick flash of blown knee or lower back. But I was fine. I don't think a person that didn't use deadlifts & squats on a regular basis could have taken that drop. I kept walking like it was nothing, completely shocked I didn't fall. I had enough muscle to absorb the impact.
it seems like most injuries (for well-trained people) occur doing silly things.
An untrained person is going to pull his back picking up groceries. We got that shit.
But today my back got funny for a minute just bending over sideways to pick up a book off a desk I don't use. Some weird angle of height and twisting (and it's cold/rainy). Instant sensation of "I'm going to the ER"... then i stretched and whatever kink it was, disappeared and I was fine.