What 'Lift With Your Legs' Really Means
If the phrase “lift with your legs” never made any sense to you, you’re not alone. Trying to follow this advice can feel awkward, unnatural, and ineffective—even though it’s not wrong, exactly. One 1993 study showed that even when warehouse workers had been trained to “lift with the legs,” and even when they said they were doing their best to follow the instructions, in most cases it was pretty much impossible to lift in the textbook manner.
Why everyone wants you to lift with your legs
The main point of lifting with your legs is to avoid one particular mistake: rounding your lower back so forcefully that you’re putting yourself at risk for a herniated disc. If you lift something by squatting down, with your back vertical, you avoid that mistake. This turns the lift into a squat: Your back doesn't bend, but your legs and hips do.
Squatting with a weight makes a lot of sense if you're picking up something heavy from, say, a table. Instead of hunching over with your torso, it's better to bend your knees, hug the object, and then straighten your legs to stand up.
But when you're picking something up off the floor, the squat doesn't actually work very well, as those 1993 workers demonstrated. You need to actually get the item off the ground somehow, and most people don't have the mobility to start a squat all the way from the floor. If you're used to doing squats and deadlifts, you'll notice another problem: Weights that are hard to squat (especially from a deep squat) are often a lot easier to deadlift, because your back and hips are stronger than your legs.
Realistically, it is not only fine but sometimes necessary to use your back in lifting. That said, you have to pay attention to how you are lifting with your back to be able to do it right. The constant quipping of "lift with your legs" is meant to bypass this problem—you can't lift with your back incorrectly if you never lift with your back at all! But, again, we're back to the problem where the "lift with your legs" advice doesn't always give you all the tools you need for real-life lifting.
What you should actually do instead of lifting with your legs
In reality, you can move your body however you need to, as long as you keep your back roughly straight—stabilized by all those handy core muscles. I like how the Duke Environmental and Occupational Safety Office boils down lifting form to two simple rules:
Keep the load close to your body throughout the lift. Hug the load to your belly, which may mean kneeling on one knee or squatting asymmetrically, so that you’re almost straddling the thing you need to pick up.
Maintain your back’s natural curves, especially the arch in your lower back. Think of keeping your spine in the same neutral position as when you’re standing or walking.
That last one can be a little tricky to understand, but all it means is that you shouldn't bend your back or torso in any dramatic direction. Don't hunch over like a rainbow, or arch backward like, I don't know, a banana. If you bend over, it should be by using your hips as a hinge, not by curving your back.
If you master those two rules, you’ll protect your back without having to mimic any unnatural, awkward positions. Sometimes you'll see cheesy "lift with your legs" illustrations of lifting technique where a person squats to pick up a box, but then holds the box out in front of them—nobody does that, and it doesn’t even make sense. Your “power zone,” where you can lift the most, is with the object hugged to your belly. If you hug it to your chest or hips instead, that’s almost as good. Once you start holding it higher, lower, or out farther from your body, you can’t handle nearly as much weight safely. (This lifting guide has more illustrations showing how to pick up heavy boxes safely.)
Those two rules also explain why deadlifts are possible as a safe gym exercise: People who do those lifts make sure to keep their spine neutral, and the weight close to their body. There’s more than one way to safely lift.