Bird dog: how to do it, the harder versions, and what the studies found

The bird dog is a core exercise on hands and knees: you reach one arm forward and the opposite leg back until both are level with your body, hold, and switch. Your arm and leg move; your back and hips don't. That's the whole exercise: holding a flat, level body while it's pulled off balance and twisted by one arm and one leg.

It's the face-down partner of the dead bug, which does the same opposite-arm-and-leg job lying on your back. This page covers the setup and the position cues, the muscles the studies measured during it, how to make it harder, what one training trial found, the faults, and the sets.

How to do a bird dog

1. Set up on hands and knees: hands under your shoulders, knees under your hips, back flat like a table top, eyes on the floor just in front of your hands.
2. Set your midsection, enough that your back stays flat when you move. Don't let your belly sag or your back round up.
3. Reach one arm forward and the opposite leg back, slowly, until both are level with your body. Thumb up, heel pushing back, as if someone were pulling your hand and foot apart.
4. Hold for two or three seconds with your hips level: no tilting toward the side of the raised leg, no twisting.
5. Return both to the floor, or just brush the floor, and do the other side. One rep is one side.

A cup or a light object balanced on your lower back is an old cue for the flat back. If it would slide off, the leg is too high or your hips are turning.

Muscles worked

Most of these studies are short lab measurements of muscle activity, or of how much a muscle thickens during the exercise. They describe the bird dog during a set, not what it builds over weeks.

• The glutes. In 30 healthy adults, 19 men and 11 women, the arm-and-leg lift on all fours was the exercise of nine that the authors suggested may help strengthen the gluteus maximus; most of the rest stayed under 45% of a maximal contraction.¹
• The sides of the waist and the back muscles, crosswise. In 29 healthy volunteers, the bird dog produced its greatest activity in the internal oblique on the side of the raised arm and in the erector spinae, the long back muscles, on the opposite side.² That's the twist the exercise asks you to resist.
• The back muscles, more than crawling. In 31 healthy young men, the erector spinae thickened more in the bird dog than lying on the back, in a lying heel lift or crawling on all fours.³
• A deep back muscle, with less help from the surface ones. In 34 healthy adults with fine-wire electrodes, the deep multifidus was more active in a reverse hyperextension than in the bird dog, but in the bird dog it did the largest share of the work relative to the surface back muscles of the four exercises tested. Adding 10% of body weight made a negligible difference.⁴
• The deep abdominals. In 44 healthy young adults doing seven core exercises, the bird dog ranked first for the thickness of the transversus abdominis, the deepest abdominal muscle, and with the side plank showed the greatest overall increase when the belly was drawn in.⁵

How to make it harder

Two studies measured the levels. In 10 healthy men doing the bird dog at five levels of difficulty, peak activity in the multifidus and the erector spinae rose as the level went up.⁶ In 57 physically active young men with a phone strapped to the pelvis to measure wobble, lifting an arm and a leg was harder than lifting one limb, a knee on a half-ball was harder than a forearm on it, and moving the limbs was harder than holding them still.⁷ A ladder, from easiest:

1. One limb: one arm forward, or one leg back, the other three on the floor.
2. The full bird dog, opposite arm and leg, with a hold at the top.
3. Moving: from the top position, bring the elbow and the opposite knee in under you, then reach long again, without touching down.
4. Longer holds, 5 to 10 seconds, still level.
5. Less stable: the supporting knee on a cushion or a balance pad.
6. Loaded: a light ankle weight or a band around the working foot, kept only while the hips stay level.

What six weeks of it did in one trial

In a six-week trial, 60 physically active young men were split into a control group and two groups that trained only bridges and bird dogs, twice a week, at a measured difficulty: one with harder versions, one with more volume. Neither training group improved more than the control group on the trunk stability, trunk endurance or balance tests. Between them, the harder-version group changed somewhat more on the bridge and bird dog control tests themselves, and the higher-volume group on the endurance tests, but those differences between the two groups weren't significant either.⁸ The authors suggest the doses, typical of warm-ups and fitness routines, were low, and that the men had no apparent trunk-control deficits to begin with.

So the trial supports a narrow reading: the bird dog trains you at the bird dog. It's a good way to learn to hold your body still while your limbs move. It isn't, on this evidence, a substitute for the heavier work in the core workout, and this page makes no claim about the back itself.

The common faults, and a fix for each

• Leg too high. Level with your body is the top; higher just arches the lower back.
• Hips tilting toward the raised leg. Keep both hip bones pointing at the floor. Lower the leg until they do.
• Back sagging or rounding. Flat like a table top, before and during the reach.
• Rushing. Two seconds out, a hold, two seconds back.
• Looking up. Eyes on the floor in front of your hands keeps your neck in line.
• Training through something that hurts. Working muscles are normal; a sharp or lasting hurt isn't. Stop, and see a doctor or a physical therapist.

Sets, reps and where it goes

• Two or three sets of 6 to 10 reps a side, each with a two- or three-second hold, stopping while every rep is still flat and level.
• In a core block at the end of a session, beside the plank and the dead bug.
• As a warm-up, one easy set before a lifting session.
• Progress one step of the ladder at a time, only when the step before is easy and still.

If you'd rather not plan it alone

The bird dog takes a minute to learn; deciding how much core work your week needs, and which of it should be harder, is the part a page can't do. Coaching is the version where your workouts are built around the days you actually have, and a weekly call looks at the week you just had and rebuilds the next one. Coaching to build muscle explains how that works, and here's how to apply. Otherwise: at the end of your next session, do two sets of eight bird dogs a side with a three-second hold, and write down which step of the ladder you used.