Dead Bug
The dead bug is a floor core exercise in which you lie on your back with your arms reaching up and your knees bent over your hips, then reach the opposite arm and leg away while your back stays flat. It trains the stomach muscles to hold the trunk still against the pull of the moving limbs, and it is a common warm-up and core-control exercise.
Also called: Deadbug, Supine Contralateral Limb Lower, Lying Anti-Extension · Equipment: bodyweight · Pattern: isolation
Step by step
- Lie on your back and lift your legs so your knees are bent to 90° and stacked over your hips, with your shins parallel to the floor.
- Reach both arms straight up so your hands are above your shoulders, and rest your head on the floor.
- Breathe out and brace so your back presses gently flat into the floor and your ribs stay down.
- Slowly reach one arm back overhead while straightening the opposite leg out until it hovers just above the floor, or as far as your back stays flat.
- Bring the arm and leg back to the start under control.
- Repeat with the other arm and leg, alternating sides on each rep.
- After the last rep, bring both knees back over your hips, set your feet on the floor and roll to your side to sit up.
- Back flat into the floor
- Opposite arm and leg reach away together
- Breathe out as the limbs reach long
- Reach only as far as your back stays flat
- Head heavy, neck long
- Ribs down throughout
In VALDA, these cues are one tap away on the exercise while you train.
What it trains
| Muscle | Role | Evidence |
|---|---|---|
| Rectus abdominis | Prime mover | C |
| Obliques (internal/external) | Prime mover | C |
| Transverse abdominis | Stabiliser | C |
| Erector spinae | Stabiliser | C |
| Hip flexors | Dynamic stabiliser | C |
Evidence grades: A = strong research base · B = good · C = limited · D = coaching consensus.
What goes wrong, and the fix
Back arching off the floor
Fix: Only reach as far as your back stays flat, keeping the knee bent if needed.
Rushing the reps
Fix: Take two to three seconds to reach out and the same to come back.
Lifting the head
Fix: Rest your head on the floor and keep your neck long.
Holding the breath
Fix: Breathe out steadily as the arm and leg reach away.
Moving the same-side arm and leg
Fix: Pair each arm with the opposite leg on every rep.
Ribs flaring as the arm goes overhead
Fix: Keep your ribs down and reach the arm only as far as your back stays flat.
What the research says
Rehab & prehab · first choiceGeneral fitnessSport performanceEndurance
- Muscle activity — An EMG study of the dead bug found abdominal activity was higher when the arms and legs moved together than with the arms alone, and higher at a faster pace. EMG measures activity, not growth.
- Lever length — An EMG study of a graded five-level core test found abdominal activity was generally higher at the levels with the legs further from the body, which is why straightening the leg makes the dead bug harder.
- Reps — Many programmes use 2–4 sets of 6–10 slow reps per side. There is no research on the best rep range for this exercise.
- Placement — Many lifters use the dead bug as a warm-up before squats and deadlifts or at the end of a session, often several times a week given its small fatigue cost.
- Progression — A common approach is to master the bent-knee version first, then straighten the leg, then add a band or light weight. There is no research comparing progressions.
Swap it mid-workout
With VALDA Pro, FLEX offers alternatives like these when you swap an exercise mid-workout.
Log the dead bug in VALDA, with these cues one tap away while you train and your history for it in one place.
General information about exercise technique, not medical advice. If you have an injury or a health condition, your healthcare provider is the right person to ask.