You have definitely heard the saying “bend with your knee, not your back”. In theory, this is to keep a “flat back” which is a protected back. But practically speaking only bending with your knees may put you at a disadvantage.
You probably know someone who has “thrown out their back” while lifting something, doing a half bend, or picking something up off the floor. I can tell you that as a chiropractor I know many of these people.