What muscles does the bird dog work?

The muscles either side of your lower spine, holding your back still against a limb reaching away from it. Your glutes extend the leg and your shoulder holds the arm out. Among four graded trunk exercises, this was the one where the spinal muscles rose while the curl up was where the abs and obliques did.

Is the bird dog a lower back exercise or a core exercise?

Both descriptions point at the same thing done badly. It trains the muscles alongside your lower spine, and it trains them to hold a position rather than to bend and straighten it. Nothing about your back should move during a rep.

Why is this called the advanced bird dog?

Because the catalog treats raising one arm and one leg together as the step after raising each on its own. In the research that measures the exercise, that combined version is simply what a bird dog is, so treat the single limb versions as the way in rather than as a different exercise.

How high should I lift my arm and leg?

To the line of your back and no further. Clinical descriptions of the exercise cap it at parallel with the floor, because the height above that comes from arching your lower back, which is the movement the exercise is built to prevent.

Why does my hip rotate when I lift my leg?

Reaching a leg backward applies a twist to your pelvis, and turning is easier than holding. It is the exercise showing you where its limit is. Lift only as high as you can with both hip bones still facing the floor.

Is the bird dog good for lower back pain?

We cannot answer that, and neither can any of the studies behind this page. They measured muscle activity and how well people tolerated the exercise, not whether backs improved. That question needs someone who can see you.

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Bodyweight · intermediate · back

Bird dog advanced

Also called Bird dog, Quadruped opposite arm and leg raise, Quadruped arm and leg reach.

The short answer

The bird dog raises one arm and the opposite leg from a position on all fours, holds them out level, and swaps sides. The muscles either side of your lower spine are what it trains, and their job is to keep your back completely still while a limb reaches away from it. Nothing about your spine bends, which is the part the name Lower back tends to hide. Your glutes lift the leg and your shoulder holds the arm out.

How to do it

Step oneStart on all fours with your hands directly under your shoulders and knees under your hips.
Step twoBrace your core and simultaneously extend both your right arm forward and left leg back.
Step threeHold the extended position briefly, keeping your hips level and back flat.
Step fourReturn to the starting position and repeat on the opposite side, extending your left arm and right leg.
Step fiveContinue alternating, maintaining a neutral spine throughout.

What usually goes wrong

Each starts with what you would notice.

The hip on the side of your raised leg turns open toward the ceiling.

WhyRotation is what this exercise exists to resist, so rotation is the first thing that gives. Reaching a leg back applies a twist to your pelvis, and if the trunk stops holding, the pelvis turns instead of the leg going higher.

FixLift the leg to the height you can reach with both hip bones still pointing at the floor, and no higher. Balancing something light on your lower back makes the turn obvious the moment it happens.

Your arm and leg finish above the line of your back.

WhyThere is only so far the shoulder and the hip will reach on their own, and the extra height after that comes from your lower back arching. That is spinal movement in an exercise built on the spine not moving.

FixStop the arm and the leg level with your back and let that be the top. McGill's own description of the exercise says the arm and the leg should not go past horizontal, for exactly this reason.

Your whole body leans toward the arm and knee still on the floor.

WhyTwo limbs have left the ground on the same diagonal, so your base is now two corners of a square instead of four, and leaning is the easy way to keep from tipping.

FixSet your supporting hand and knee where the catalog steps put them, under the shoulder and under the hip, and push evenly into both. If you cannot get a limb out without leaning, raise one limb at a time until you can.

You are swapping sides continuously and never quite arriving anywhere.

WhyThe reps have run together, so the extended position exists for a fraction of a second between two transitions rather than being held.

FixReach out, arrive, and stay there long enough to notice whether anything is drifting. The catalog steps ask for a brief hold, and the hold is where you find out if your hips are level.

Both limbs or one at a time

The catalog calls this the advanced version, and there is a real ladder underneath that. Clinical progressions start on all fours with the back set in a neutral position, then raise one arm on its own, then one leg on its own, and only combine them once each half can be done without the pelvis or the shoulders rocking.

Where the label gets misleading is that in the studies that actually measure this exercise, a bird dog already means the opposite arm and leg going up together. That is the version researchers put on the table when they compare it with other trunk exercises. So the arm-only and leg-only versions are steps toward the exercise rather than easier flavors of it.

Practically: if the diagonal version rolls your hip open every time, one limb at a time is not a lesser exercise, it is the one you can currently do correctly. Combining them when you cannot hold the position trains the rocking, not the holding.

Bird dog or dead bug

They are mirror images. One has you face down on all fours reaching a limb away from you; the other has you on your back reaching a limb away from you. Both are asking the trunk to stay still while something moves.

The mirroring changes which muscles it lands on, because gravity is coming from a different direction. Face down, the reach threatens to arch your back, so the muscles either side of the spine hold against it. Face up, the reach threatens to pull your back off the floor, so the front of your trunk holds against it.

Both were included in one study of four graded trunk exercises. What that study reports is which exercise moved which muscle: the muscles alongside the spine rose with the bird dog, and the abs and obliques rose with the curl up. It does not give a head to head ranking of bird dog against dead bug, so we are not going to invent one. Doing both covers two directions, which is the honest reason to have both.

What the lower back is actually doing here

Filing this under the lower back is correct and it reads wrong, because most exercises filed there involve bending and straightening the back. This one does not, and the difference matters more than the label.

The clearest evidence for what is happening is diagonal. In 29 volunteers, the bird dog produced its highest readings in the internal oblique on the side of the raised arm and in the spinal muscles on the opposite side. That is a corner to corner pattern across the trunk, which is what you get from resisting a twist. It is not the pattern you get from extending a back.

So the demand comes from geometry rather than from effort. An arm reaching forward and a leg reaching back both apply a turning force to your trunk, from opposite corners, and the exercise is whether your back holds still against them. Reaching further makes the demand larger. Arching to reach further removes it entirely, which is why the height limit is not fussiness.

It is also worth being clear that this is not a hard exercise in the way a heavy set is hard. The load is your own arm and leg held out on a lever, and the demand is precision rather than effort: the further you reach, the larger the twist your back has to refuse, and arching to reach further removes the twist instead of adding to it. That is the point of the exercise rather than a criticism of it.

The bird dog is best known as one of three exercises Stuart McGill set out as a basic low back program, alongside a curl-up and a side bridge, chosen to load muscle while keeping the load through the spine small. What gets lost when that program is repeated online is that the limb positions were never the whole of it. Holding the back in one neutral position throughout, and stopping the reach where that position ends, is the exercise. Copying the shape without that is a different movement wearing the same name.

One thing we will not tell you is whether it helps a back. Every study here measured muscle activity. None of them measured whether anyone got better. If something hurts and keeps hurting, that is a question for a physiotherapist.

What it is for

The bird dog advanced (both hands raise) is a bodyweight exercise targeting the lower back and core stabilizers. By simultaneously extending opposite limbs from the quadruped position, this advanced variation increases the balance and stability demand compared to the standard bird dog, developing spinal control and full-body coordination.

Questions people ask

What muscles does the bird dog work?: The muscles either side of your lower spine, holding your back still against a limb reaching away from it. Your glutes extend the leg and your shoulder holds the arm out. Among four graded trunk exercises, this was the one where the spinal muscles rose while the curl up was where the abs and obliques did.
Is the bird dog a lower back exercise or a core exercise?: Both descriptions point at the same thing done badly. It trains the muscles alongside your lower spine, and it trains them to hold a position rather than to bend and straighten it. Nothing about your back should move during a rep.
Why is this called the advanced bird dog?: Because the catalog treats raising one arm and one leg together as the step after raising each on its own. In the research that measures the exercise, that combined version is simply what a bird dog is, so treat the single limb versions as the way in rather than as a different exercise.
How high should I lift my arm and leg?: To the line of your back and no further. Clinical descriptions of the exercise cap it at parallel with the floor, because the height above that comes from arching your lower back, which is the movement the exercise is built to prevent.
Why does my hip rotate when I lift my leg?: Reaching a leg backward applies a twist to your pelvis, and turning is easier than holding. It is the exercise showing you where its limit is. Lift only as high as you can with both hip bones still facing the floor.
Is the bird dog good for lower back pain?: We cannot answer that, and neither can any of the studies behind this page. They measured muscle activity and how well people tolerated the exercise, not whether backs improved. That question needs someone who can see you.