What Muscles Does Back Extension Work? A Simple Guide

What muscles does back extension work?

You may be wondering why the back extension is so frequently included in strength programs and why it’s such an important exercise. To understand why you’re doing it, you should know which muscle groups it targets and the roles they play in the movement.

So what muscles are used in the back extension? The spinal erectors and the muscles of the lower back are the main muscle groups worked in the back extension. They help you stand upright when you’re in a bent over position. The glutes and hamstrings also play a role in extending your hips as you lift your torso.

In this article, I’ll review each of the muscles used in the back extension and discuss ways to identify weaknesses in the muscles that are involved in the back extension. I’ll also discuss the muscles used in different variations of the back extension.

Muscles Worked While Doing Back Extensions (Basic Anatomy and Biomechanics)

muscles worked while doing back extensions

While many consider the back extension to be an isolation exercise for the lower back, it works a few other muscle groups as well.

The muscles used in the back extension are the :

  • Erector spinae (muscles that run up and down the spine)
  • Quadratus lumburom (muscles on the sides of your lower back)
  • Glutes
  • Hamstrings

Erector Spinae

The erector spinae are a group of three different muscles that run up the length of the spine: the illiocostalis lumborum, the longissimus thoracis, and the spinalis.

In the back extension, these muscles aid in the extension of the spine as you’re raising yourself back up from a bentover position.

Quadratus Lumborum

The quadratus lumborum is a muscle deep in your abdominals that sits on each side of your lumbar spine in your lower back.

Together with the erector spinae, this muscle aids in extension of the spine during the back extension. It also acts as a stabilizer and prevents your spine from twisting as you’re lowering and lifting your torso.


While the glutes aren’t the primary muscle group used in the back extension, they do play a role in extending the hips as you straighten your torso.

To activate the glutes even more, you can perform a back extension with your upper back rounded. I generally don’t recommend doing this when you’re new to the back extension because it can lead to you arching your lower back as well if you’re not careful, and that places extra stress on the spine.

But if you’re an experienced trainee, you can experiment with this variation. The rounded upper back position reduces the range of motion so your glutes remain engaged the entire time rather than just coming into play as you’re lifting yourself back up.


The hamstrings aren’t completely isolated during the back extension, but together with the glutes, they aid in hip extension as you’re returning to a more vertical position.

Can’t do a back extension? Check out our Best Back Extension Alternatives

Identifying Weak Muscles in the Back Extension

Identifying Weak Muscles in the Back Extension

The back extension may not be quite as technical as the squat or deadlift, but it is possible to have muscle weaknesses that prevent you from executing the movement properly.

Many of the common mistakes of the back extension are due to technical flaws, but they can also be caused by weaknesses in the muscles involved in the movement. Let’s take a look at some of these mistakes and discuss the reasons why they point to muscular weaknesses.

Hyperextending The Back

Back extensions are sometimes also called hyperextensions, but that doesn’t mean you should actually be hyperextending your back at the top of the movement.

If you find yourself doing this, it could stem from a lack of control and positional awareness. Having a trainer watch you or filming yourself while you’re doing back extensions can let you see if you’re moving through too large of a range of motion. You’ll then be able to practice and correct yourself the next time you do the exercise.

Trouble Keeping Your Spine Rigid

If you find it difficult to maintain a rigid torso during the back extension, you may have weak spinal erectors. And while the back extension will help you strengthen those muscles, it’s not worth doing if you have weaknesses that prevent you from doing it correctly.

Not being able to keep your back flat could also mean that your traps and rhomboids are weak. While they aren’t heavily involved in the back extension, they do play a role in helping you keep your shoulders down and back, which is important for maintaining a rigid spine.

It should also be noted that this is different than intentionally rounding your upper back to activate more of the glutes, as I described above. If you physically cannot keep your back straight during the back extension, it’s a sign that you have other muscular weaknesses to address.

Trouble With The Hip Hinge

The hip hinge sounds simple, but it can be difficult for many people to perform while maintaining a neutral spine. It’s especially challenging for people who sit all day for work, which causes tightness in the hips.

If you’re having trouble mastering the hip hinge, it could be a sign that you have poor hip mobility, which is also a common indicator of weak glutes and hamstrings.

To overcome this, you should incorporate 10-15 minutes of mobility work every day while also working on your glute strength through exercises like hip thrusts.

Lower Back Pain After Doing Back Extensions

You can expect a small amount of lower back fatigue after doing back extensions, but you shouldn’t have debilitating pain. If you do, you are likely moving through too large of a range of motion, as I already explained above, or letting your lower back round throughout the movement.

As is the case with hyperextending your back at the top, letting your lower back round can also be due to a lack of body awareness. But it could also point to weak abdominals or an inability to brace your core properly.

A strong core is just as important as a strong posterior chain, and if you aren’t working on strengthening the front of your abdominals, your lower back could be overcompensating. You may benefit from adding some direct core work to your routine.

Muscles Used in Different Variations of the Back Extension

Each back extension variation works many of the same muscle groups as the back extension, but certain muscles are activated more or less depending on the movement.


Supermans are an equipment-free variation of the back extension. They’re done by lying face-down on the floor with your arms outstretched and lifting your chest and legs as much as you can. Because you’re on the floor, Supermans don’t provide a large range of motion, but they work the lower back, glutes, and hamstrings.

In addition to performing spinal extension, as is the case in the back extension, the spinal erectors are also responsible for spinal flexion. When doing Supermans, they allow you to flex your spine in a backward motion as you’re raising your chest and legs from the ground.

The glutes are also activated as you’re lifting your chest and legs. And despite the limited range of motion, there is some hip extension involved in the Superman, which is where the hamstrings come into play.

Reverse Hypers

Reverse hypers are a little bit different than back extensions but they still target the glutes, hamstrings, and lower back.

Reverse hypers are sort of like a reverse hip hinge. Instead of starting in a vertical position and hinging forward at the waist, you start in a hinged position and swing your legs out behind you.

When doing a reverse hyper, you’ll rest your torso on a reverse hyper bench or another elevated, stable surface that allows your legs to hang down with your feet off the ground. You then use your lower back, glutes, and hamstrings to swing your legs back.

All three muscle groups work in tandem to extend the hips as your legs move behind you and your body becomes more horizontal to the floor.

Good Mornings

Good Morning

Good mornings are a barbell exercise in which you bend forward at the waist while holding a bar across your back. This is an excellent exercise for people who want to strengthen the posterior chain but don’t have access to a back extension machine.

In the good morning, the spinal erectors work to extend the spine as you return to a standing position. They also help stabilize the spine and keep it in a neutral position.

As well, the glutes and hamstrings are responsible for hip extension as you lift your torso back up.

Romanian Deadlifts

romanian deadlifts

Romanian deadlifts are another barbell exercise that strengthen the posterior chain, but you can do them with dumbbells, kettlebells, or bands as well.

Romanian deadlifts are typically performed with just a slight bend in the knees. This allows for greater activation of the hamstrings. They work to extend the hips and move them towards the bar as you rise from the bottom of the movement.

The spinal erectors aid in hip extension as well, but their primary role in the Romanian deadlift is to stabilize the spine and prevent you from rounding your back.

And just like they do in the back extensions, the glutes also work to extend the hips as you’re lifting your torso from the bottom position of a Romanian deadlift.

Final Thoughts

The back extension is an excellent exercise for working the spinal erectors, glutes, hamstrings, and lower back muscles.

The spinal erectors are the primary muscles involved in the movement because they aid in spinal extension as you’re rising from a bentover position. The quadratus lumborum in the lower back also helps keep your spine from rotating while the glutes and hamstrings work together to extend the hips.

There are several variations and alternatives to the back hyperextension if you don’t have access to a back extension machine. For example, Supermans are a bodyweight exercise that can be done anywhere while good mornings and Romanian deadlifts can be done with a barbell and plates.

I’d also recommend doing Romanian deadlifts and good mornings in place of back extensions if you want to target your hamstrings more.

Other Back Extension Resources

About The Author

Amanda Dvorak

Amanda Dvorak is a freelance writer and powerlifting enthusiast. Amanda played softball for 12 years and discovered her passion for fitness when she was in college. It wasn’t until she started CrossFit in 2015 that she became interested in powerlifting and realized how much she loves lifting heavy weights. In addition to powerlifting, Amanda also enjoys running and cycling.