What muscles does the reverse Nordic curl work?

The quads, working while lengthening as you lean back. Rectus femoris takes the most of it, because it is the one quad head that also crosses the hip and this position keeps the hip open while the knee bends. Behind that, your glutes are stopping your hips from folding and your abs are stopping your back from arching. Both are working hard without moving anything.

Is the reverse Nordic curl the same as the Nordic hamstring curl?

No, it is the opposite one. The Nordic lowers you forward and your hamstrings resist it. The reverse Nordic lowers you backward and your quads resist it. Same kneeling start, different direction, different muscle.

Why is my lower back doing all the work?

Because your back is arching to buy range your knees were meant to give. Pull your ribs down toward your hips and go back only as far as you can without the arch appearing. That distance will be short at first, and it is the real one.

How sore should I expect to be?

Very, after the first session, and we would rather say so than be reassuring about it. Lowering under load is what produces soreness, it has been measured at the knee extensors peaking between 24 and 72 hours, and the second session is far milder than the first. Do less than you think you can on day one.

Does the reverse Nordic prevent quad injuries?

Nobody has measured that. What has been measured is what it does to the muscle: 8 weeks of it lengthened the fascicles in rectus femoris by about 10 percent, and 4 weeks of stopping gave back about half of that. Whether that changes injury rates is an open question, and the Nordic hamstring curl's injury record does not carry across to it.

How far back should I lean?

As far as you can lean and still get yourself back up, which is likely a few inches at the start. The range you can reverse is the range you have, and it grows over weeks rather than within a session.

What is this exercise actually called?

Most people call it a reverse Nordic curl, or just reverse Nordics. You will also see natural leg extension and bodyweight leg extension. The research calls it the reverse Nordic hamstring exercise, which is a confusing name for a quad exercise, and it is worth knowing so you can find the studies.

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Bodyweight · advanced · upper legs

Reverse Nordic curl

Also called Reverse Nordic, Reverse Nordic hamstring exercise, Natural leg extension, Bodyweight leg extension, Kneeling quad extension.

The short answer

The reverse Nordic curl is a knee-bend done backward from tall kneeling. You kneel up, hold your hips open, and lean backward under control so your knees bend while your body stays in one line from knees to head. Your quads do the work, and they do it while lengthening, which is a different job from lifting you back up. Your glutes hold your hips open and your abs keep your ribs where they are, and neither of those is producing the movement.

How to do it

Step oneKneel on both knees on a mat with your body upright.
Step twoSlowly lean back by extending at the knee joint, lowering your torso toward the ground.
Step threeKeep your hips forward and your body in a straight line from head to knees.
Step fourHold for a moment at the lowest comfortable point, then contract your quads to return to upright.

What usually goes wrong

Each starts with what you would notice.

You lean back and the front of your thighs barely notices.

WhyYour hips have folded, so your backside is drifting toward your heels rather than staying stacked over your knees. That brings your weight closer to the joint it is turning around, and a shorter distance means less for the quads to hold.

FixSqueeze your backside before the first rep and keep your hip bones pointing forward the whole way down. If holding that limits you to a small lean, the small lean is your range today.

The lean shows up as an ache in your lower back.

WhyYour ribs have flared and your back has taken the range the knees were supposed to give, so the movement is happening above your hips instead of below them.

FixPull your ribs down toward your hips and start again from upright. Whatever distance you can travel with the ribs down is the part that belongs to your quads.

You get partway back and then drop the rest of the way.

WhyThe further you lean, the more of your bodyweight hangs off your knees, so the position keeps getting harder right through to the bottom. Most people run out somewhere in the last third.

FixStop the descent while you can still reverse it, and end the set on the first rep that needs rescuing. Reaching both arms forward as you go acts as a counterweight, and setting your hands down behind you turns a rep you cannot finish into a controlled stop rather than a fall.

You could barely get down stairs for three days after your first session.

WhyLowering under load is the version of muscle work that reliably produces soreness, and it has been measured at the knee extensors doing exactly that: soreness peaking somewhere between 24 and 72 hours, with a measurable drop in force while it lasts.

FixDo far less than you think on the first session, a handful of short reps and nothing more. The second session is much milder than the first, and that pattern is well documented, so the first one is worth underdoing.

The front of your knee hurts before you have leaned back at all.

WhyYou are kneeling with your bodyweight through the front of your knee on a hard floor, which is a separate problem from the exercise.

FixKneel on a folded mat or a doubled towel. If something hurts and keeps hurting, that is a question for a physiotherapist.

Reverse Nordic curl or Nordic hamstring curl

The names are two words apart and the starting positions look alike from across a room, which is why these two get mixed up constantly. They are opposites.

A Nordic hamstring curl kneels you down with your ankles held and lowers you forward, face toward the floor. Your hamstrings resist that, so the muscle that bends your knee is the one slowing the fall. The reverse Nordic kneels you down with nothing holding your ankles and lowers you backward. Your quads resist that, so the muscle that straightens your knee is the one slowing the fall.

One is a hamstring exercise and one is a quad exercise, and which way you are leaning is the whole of the distinction.

They also sit a long way apart in how much evidence exists. The Nordic has been studied for injury rates across thousands of athletes. The reverse Nordic has one 8-week study of what it did to a muscle and one study of how hard it works the quads. Both are worth doing. Only one of them has that kind of record behind it.

Reverse Nordic or a single-leg squat

This comparison got measured, and the result is not the one the reverse Nordic is usually sold with.

Researchers set it against three bodyweight squat patterns, a single-leg squat, a forward lunge and a Bulgarian split squat, and recorded how hard the quads worked on the lowering half of each.

The reverse Nordic came out similar to the squat patterns for two of the three quad muscles measured, and lower than the single-leg squat for the third. Among the squats themselves, the single-leg squat beat both the lunge and the Bulgarian split squat across all three.

Read that as a correction rather than a reason to drop it. It needs no equipment, it holds your hip open in a way a squat does not, and it is genuinely difficult. It is not, on the evidence, the hardest thing you can ask your quads to do on the way down.

What the fascicle study found, and what it did not

This exercise is nearly always introduced as the quad version of the Nordic hamstring curl, with the implication that it protects the front of your thigh the way the Nordic protects the back of it. One of those two has injury data. The other does not.

What the reverse Nordic has is an 8-week training study in 26 people who had never done it before. It used ultrasound to measure rectus femoris, the quad head that also crosses the hip. Fascicle length went from 7.82 cm to 8.57 cm, roughly 9.6 percent, and muscle thickness, pennation angle and cross-sectional area all rose significantly alongside it. That is a real change in a muscle, produced by a bodyweight exercise, in 8 weeks.

The half of that study nobody quotes is what happened next. After 4 weeks of not doing it, every one of those measures fell significantly again. The changes were reversible, and the authors say so outright.

What has never been measured is whether any of it lowers the rate of quad strains or knee problems. No trial has looked. The Nordic hamstring curl earned its reputation from injury counts across 8459 athletes in team sports, and the reverse Nordic has nothing of the kind. The analogy between them is a hypothesis, not a finding.

So the honest summary is this. It changes the muscle while you keep doing it, we do not know what that buys you, and it will make you very sore the first time.

What it is for

The kneeling quad extension is an advanced bodyweight exercise that eccentrically loads the quadriceps by leaning backward from a kneeling position. It builds significant quad strength and is used as a progression toward exercises requiring knee flexion control.

Questions people ask

What muscles does the reverse Nordic curl work?: The quads, working while lengthening as you lean back. Rectus femoris takes the most of it, because it is the one quad head that also crosses the hip and this position keeps the hip open while the knee bends. Behind that, your glutes are stopping your hips from folding and your abs are stopping your back from arching. Both are working hard without moving anything.
Is the reverse Nordic curl the same as the Nordic hamstring curl?: No, it is the opposite one. The Nordic lowers you forward and your hamstrings resist it. The reverse Nordic lowers you backward and your quads resist it. Same kneeling start, different direction, different muscle.
Why is my lower back doing all the work?: Because your back is arching to buy range your knees were meant to give. Pull your ribs down toward your hips and go back only as far as you can without the arch appearing. That distance will be short at first, and it is the real one.
How sore should I expect to be?: Very, after the first session, and we would rather say so than be reassuring about it. Lowering under load is what produces soreness, it has been measured at the knee extensors peaking between 24 and 72 hours, and the second session is far milder than the first. Do less than you think you can on day one.
Does the reverse Nordic prevent quad injuries?: Nobody has measured that. What has been measured is what it does to the muscle: 8 weeks of it lengthened the fascicles in rectus femoris by about 10 percent, and 4 weeks of stopping gave back about half of that. Whether that changes injury rates is an open question, and the Nordic hamstring curl's injury record does not carry across to it.
How far back should I lean?: As far as you can lean and still get yourself back up, which is likely a few inches at the start. The range you can reverse is the range you have, and it grows over weeks rather than within a session.
What is this exercise actually called?: Most people call it a reverse Nordic curl, or just reverse Nordics. You will also see natural leg extension and bodyweight leg extension. The research calls it the reverse Nordic hamstring exercise, which is a confusing name for a quad exercise, and it is worth knowing so you can find the studies.