Dead bug: how to do it, the harder versions, and what it trains

The dead bug is a core exercise done on your back. You start with your arms pointing at the ceiling and your knees bent over your hips, like an upturned beetle, then slowly lower one arm and the opposite leg toward the floor while your midsection holds your lower back and pelvis still. The job is not to move: the arm and leg are just the load your abs work against.

It's the starting point the core workout suggests before the plank. This page covers the steps, what the studies measured in the abdominal muscles during it, the harder and weighted versions, the faults, and the sets.

How to do a dead bug

1. Lie on your back with your arms straight up over your shoulders.
2. Lift your legs so your hips and knees are bent to 90 degrees, shins level with the floor.
3. Set your midsection: breathe out and let your ribs come down, so your lower back rests on the floor. That contact is your checkpoint for the whole set.
4. Reach one arm back over your head and straighten the opposite leg out toward the floor, both slowly, about two or three seconds, stopping just above the floor or sooner if your lower back starts to lift.
5. Bring them back to the start and do the other side. One rep is one side.

Slow is the point. If you can do it fast, slow it down until you can't.

What the dead bug trains

The studies here measured the abdominal muscles by ultrasound, as how much thicker they got during an exercise, or by electrical activity. Both are snapshots during a set:

• The deepest abdominal muscle. In 44 healthy women with Pilates experience, the dead bug produced a larger increase in the thickness of the transversus abdominis, the deep muscle that wraps around the waist, than the hundred, the hip roll, the side plank or a basic lying position.¹
• No clear difference from other core exercises, in a smaller study. In 13 healthy adults, transversus abdominis thickness showed no difference between the dead bug, the plank, the side plank, the bird dog, the glute bridge and a hip extension. The external oblique, on the side of the waist, was thicker in the dead bug than in the glute bridge or the hip extension, and the internal oblique was thicker in the side plank than in the dead bug.²
• Different muscles, different winners. In 44 healthy young adults doing seven core exercises, the dead bug and the side plank ranked first for the thickness of the multifidus, a deep back muscle, the bird dog first for the transversus abdominis, and the dead bug last for the internal oblique.³

Read together, no single core exercise came out on top for every muscle, which is why a core block mixes a few. The dead bug's place is the anti-arch job: holding your lower back down while your limbs move.

Draw in, or brace?

Two common cues: draw your belly button in toward your spine (hollowing), or tighten your whole midsection as if about to be poked (bracing). In the seven-exercise study, every exercise produced more thickening with hollowing than with bracing, averaged across the three muscles measured.³ Thicker during a rep isn't proof of more benefit over weeks. Use whichever keeps your lower back on the floor; many people find a gentle draw-in and a long breath out does it.

Harder versions, and the weighted dead bug

Level matters. In 10 healthy men doing the dead bug and three other common core exercises at five levels of difficulty each, muscle activity generally rose with each level.⁴ A ladder, from easiest:

1. Legs only: arms stay up, lower one heel to tap the floor with the knee still bent.
2. Arms only: legs stay up, reach one arm back at a time.
3. The full dead bug, opposite arm and leg, as in the steps.
4. Straighter, longer: the leg goes out fully straight, closer to the floor, with a pause at the end.
5. Weighted: a light dumbbell or plate in each hand, or ankle weights.
6. Banded: hold a band anchored behind your head, arms straight, so the band pulls while your legs move.

No study of a weighted or banded dead bug turned up in a PubMed search for this page. Move up a step only when the one before is easy with your lower back on the floor the whole set.

Dead bug or plank?

Both ask your midsection to stop your lower back from arching, the dead bug lying on your back with your limbs moving, the plank face down and still. The dead bug is the usual starting point, which is why it comes first in the core workout; in the seven-exercise study, the plank and the bridge ranked last for transversus abdominis thickness.³ They work well together: dead bugs first, then the plank as it becomes easy to hold well. The bird dog is the face-down partner, on hands and knees.

No trial that trained people with dead bugs alone and measured anything over weeks turned up in a PubMed search for this page. The page makes no claim about what weeks of dead bugs do.

The common faults, and a fix for each

• Lower back lifting off the floor. The most common one. Shorten the reach, keep the knee bent, or drop to the legs-only step.
• Going fast. Two or three seconds out, the same back.
• Holding your breath. Breathe out as the arm and leg reach.
• Same-side arm and leg. It's the opposite pair: right arm with left leg.
• Neck straining up. Head down on the floor, chin slightly tucked.
• Training through something that hurts. Working abs 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 slow reps a side, stopping while every rep still has your lower back on the floor.
• In a core block at the end of a session, beside a plank, a side plank and a carry, as in the core workout.
• Before lifting, one easy set works as a warm-up for the brace. (The warm-up has the rest.)
• Progress one step of the ladder at a time.

If you'd rather not plan it alone

The dead bug takes a minute to learn; fitting core work into a week that already holds squats and deadlifts, and knowing when to make it 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 slow dead bugs a side, and write down which step of the ladder you used.