I paggered my back @ 25 years ago through trying to lift a video game cabinet out of an amusement arcade on my own (15 & I thought I could lift anything). After that, I learned to lift properly but it still comes back.
Last month I was holding one of my moggies, leaned forward to let him down & it just went. So painful I had to take the day off work (which I actually hate doing).
This is one of the reasons I like my Ibanez SR, it's @ 8lb. Another good tool on stage is the bar stool (though maybe not for rock/punk).
Also my Markbass combo weighs less than most of the heads I've owned!