What is wrong with saying “Lift with your knees, not your back”?

How many times have you been told “lift with your knees not you back!”?

At work, doing odd jobs at home or maybe even at a BBQ, whenever you lift something, someone’s got to say it.

But what does it actually mean? And why is not the best thing to say?

What they’re trying to say

When people say this, what they’re trying to say is “don’t bend you back” or “keep your back straight.”

Back pain after lifting could be a muscle or ligament strain, or potentially a disc bulge. This could be due to over bending or twisting your spine without having the strength to appropriately support the extra load. Disc bulges are more often associated with normal wear and tear (aka ageing) but can also be the result of trauma, or direct force.

Why it’s wrong to say "Lift with your knees, not your back”

Whether it’s “lift with your knees” or “keep your back straight,” it’s still not completely accurate as it can lead to some confusion.

“Lift with your knees” forgets half the body

When you say “Lift with your knees,” you’re forgetting a whole, major joint that is in between the knees and the back.

The hips.

The glutes are the major bending and straightening movers of the hips.

They are often touted as the largest and strongest muscles of the body, so why are they forgotten during lifting?

Not only may you lose glute involvement, you also decrease the use of your powerful back extensor muscles and it’s also easier to forget about the core.

The core muscles surround the hips and back, directly protecting the back through bracing. So taking attention away from this area means you could be taking away an important protective mechanism.

“Keep your back straight” is confusing

When you say “straight back” or imply it, it is common for people to get confused with a “straight back” and a “perpendicular back.”

So they keep their back straight and upright and don’t bend forward at the hips. 

A straight line is straight, no matter what angle it is on.

You can keep a “straight,” or even better a “neutral” back posture, while you bend at your hips.

In the gym world, this is called a Deadlift, although your squats should also involve a smaller forward lean with your body and thrust back up using the glutes as well!

As already mentioned, misunderstanding the meaning of “straight back” misses the opportunity to involve the glutes and back extensors and may decrease core involvement.

It also significantly decreases the depth you can reach down to. As a demo, imagine you back is upright and tight against the wall, keep it there and try to pick something of the ground.

It’s hard, if even possible.

So then you start to see some weird compensations and funny looking lifts.

Compromises your balance

Many people, to avoid bending their back and maybe because their leg muscles are tight, squat down on to their toes, with their heels off the ground. This is not the safest strategy as it may compromise your balance, especially with a forward lean and heavy forward load. I can also place extra load through the ankles.

Increases risk to other joints

Doing all this, focusing on your knees and forgetting, well, basically the rest of your body, puts extra load through the knees in ways they either weren’t designed for or just aren’t strong enough for.

This may increase wear and tear on the knee joint. While wear and tear is 100% normal, you don’t need to stress them out more than needed.

Plus, avoiding all bending may also result in compensations of trying to reach with your arms in funny postures. Again, placing extra, inappropriate load through them.

What to say instead

The saying also goes “lift with your legs,” but again, not everyone interprets that to mean glutes!

So to protect your back it would be more accurate to say “brace your core and lift with your knees and hips,” or maybe “tense your abs and lift with your legs and arse.” - Doesn’t quite have the same ring to it. We’ll work on a better slogan and get back to you!

Although, if you see someone lifting unsafely, they might need some specific exercise prescription and lessons from the pros.

Learn from the pros

There are so many different types of lifts, as well as stretches and exercise that can help you and your staff execute them safely.

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Author: Biara Webster, Exercise Physiologist