i noticed this one day after looking into a mirror off to my side while doing cable rows (and then a friend asking me "haha, why does your back stick out like that?") when i bend over, my lower back sticks out, kind of like you'd expect my legs to continue out from it like i was lying down, but then it abruptly stops at my ass.
this is what my back looks like normally, standing up straight. i always have an arch.
then there's this. it's hard to get a picture but i think you can see what i mean. what the fuck? it kind of pushes my stomach out, too, which looks odd seeing as normally i don't have a stomach. i'm 5'9" about 160lbs.
my lower back does get sore often, and occasionally even hurts, but i thought that was normal with certain exercises. i squat atg but i work hard to keep an arch and i front squat anyway, it's never really given my back serious issues. does anyone have any insight???