How to do a Dead Bug Exercise Start in the upper sit-up position, with your knees bent. Lean backwards so your upper torso and head are flat on the floor. Bring your thighs towards your chest until they reach a 90-degree angle. This should bring your pelvis up slightly, forcing you to push your lower back into the floor. bend your knees 90-degrees. Lift both arms up vertically, keeping them straight and point your fingers towards the ceiling. Slowly extend one leg whilst engaging your glutes and core, try not to arch your lower back at any point. Simultaneously lower the opposite arm towards your head. Keep your arm straight as it brushes past your ear. Your hand and foot should hover a couple of centimetres above the floor. When you’ve fully extended, bring your leg and arm back up to the starting position. Repeat on the opposite side, alternate until you’ve reached the desired number of repetitions or time duration. The dead bug is a core exercise that mainly targets erector spinae, obliques, rectus abdominis and transverse abdominis. This is a great exercise to improve your core stability and can also help to improve posture.