No, this is not a blog about your awesome dance moves, but about how to move things (like heavy boxes) without causing a spasm in your back.
You've heard "lift with your legs, not with your back," but of course, guidelines for lifting correctly needs to be more specific than that. Using the backs of the legs (hamstrings) allows heavy loads to be lifted with the massive muscles in the backs of the legs. If you are using the fronts of the thighs (quadriceps) then sorry, you are still going to strain your low back.
What causes this low back over-load is the tucked position of the pelvis. Anytime your low back is in flexion (see movie for a visual) than the disks are primed for damage. Couple flexion with twisting and you've placed the spine in an extremely vulnerable position. Add a heavy load (piece of furniture, bag of potting soil, or box of books) and BAM! the psoas goes into a spasm to protect this area.
I made this quickie video so you can see the difference. Mostly because I don't have time to post in the middle of moving 🙂 and also because my Flip video cam was getting a lot of dust.
Ideally, we should be able to bend completely over at the hip joint with straight legs, but most of use have too-tight hamstrings, thus the bend in the knee (with the vertical shin, of course.)
I'm still going to post on how to stretch hamstrings later this week.
Really I am.
Stop bugging me, I'm trying to move.