Dead Bug
Lying on your back with hips and knees at 90 degrees, you lower one leg toward the floor while your lower back stays pinned down. Nothing about your spine is supposed to move — the abs work isometrically to resist the arch that the extending limb is trying to create, which makes this an anti-extension drill rather than a crunch.
Own the movement
Set up first, then execute. Every cue below is something you can check on your next set.
Before the first rep
- Lie flat and reach both arms straight up toward the ceiling, wrists over shoulders.
- Bring your hips and knees each to 90 degrees, shins parallel to the floor.
- Exhale hard and long to pull your ribcage down, then tilt your pelvis so your lower back flattens onto the floor.
- Squeeze your glutes lightly to lock that pelvic position — this is your starting position and it does not change all set.
- If you are unsure, put a hand under your lumbar spine and use the pressure on it as your gauge.
Every rep
Breathing & tempo — Long exhale as the limb extends, inhale as it returns. Three seconds out, one-second pause, three seconds back. The breath is a working part of the drill, not an afterthought.
Sets, reps & load
Where to start, and what to change when it stops being hard.
Bodyweight, and it stays bodyweight for a long time. Progress by range first — get the heel closer to the floor with the back still flat — then by adding the opposite arm reaching overhead, then by extending both legs at once. Only after all of that does a light dumbbell in each hand make sense. Weight added before the position is solid just makes the arch happen sooner.
What goes wrong
The errors that show up most often, and the cue that fixes each one.
Shorten the range: extend only until you feel the first hint of a gap, then come back. Keep a hand or a rolled towel under your lumbar spine so the moment it unloads you feel it and stop.
Three seconds out, three seconds back, with a one-second pause at full extension. Ten reps per side at that tempo is a set; forty fast ones are just leg movement.
Breathe out slowly through the extension and in as the leg returns. A held breath props the ribcage up, which is exactly the position you are trying to avoid.
Fix your eyes on the stationary shin and keep it vertical from the knee down. If it still drifts, press that heel gently against a wall or a foam roller to give it a reference.
Why bother
As your leg straightens, your psoas pulls on the front of your lumbar spine and your pelvis wants to tip forward into an arch. Holding your ribs down and your back flat against that pull is the entire exercise. The abs are being trained to stop movement, which is closer to what they do under a loaded bar than any crunch is.
The floor makes the drill self-scoring in a way almost no other core exercise is. Slide a hand under your lumbar spine, or press your back down onto it, and the moment a gap appears you know the rep failed. There is no way to grind out a bad set without noticing — which is why this is the drill to give someone whose back does not tolerate flexion.
Where it fits
Warm-up before squats and deadlifts, or at the end of a session, three to five times a week. Sets are short and quality-driven: 6-10 slow reps per side. It pairs well with a side plank and a bird dog, and it is the right substitute when repeated crunching bothers your lower back.
If this one isn't it
No kit, too hard, or too easy — here's where to go instead.
Asked and answered
I do not feel this in my abs at all. Is it working?
If your lower back stays flat and you are moving slowly, yes. Anti-extension work produces a low, steady burn deep in the abdominal wall rather than the sharp pump of a crunch. If you genuinely feel nothing, you are almost certainly letting the back arch — shorten the range and check the gap under your spine.
Should my heel touch the floor?
Only if your back stays down when it does. Range is the progression here, not the standard. Most people should stop 15-30 cm off the floor at first and earn the last stretch of travel over several weeks.
Dead bug or plank?
Both resist extension, so pick by what you need. The plank is a static hold and easy to cheat by sagging. The dead bug adds moving limbs, which is harder to fake and closer to what happens when you carry or press something. Doing both is fine; if you only do one, the dead bug gives you clearer feedback.
Can I do this every day?
Yes. It is low-load, low-fatigue work with no eccentric damage worth speaking of, so three to five sessions a week is reasonable and daily is fine as a warm-up. Keep the reps slow — the day it becomes something you rush through, it has stopped doing its job.