Hollow rock

Muscle group

Abdomen

Primary muscles

Abs

Secondary muscles

Obliques

1. Lie on your back. Lift your legs and shoulder blades off the floor, keeping your lower back pressed firmly into the ground.
2. Keeping your core tight and your body in this curved position, gently rock back and forth from your shoulders to your hips.
3. Maintain this tight, curved position throughout the movement.