Scorpion ("Prone scorpion" Lower trunk rotation/extension, heel to opposite hand, prone)

Lie on your front with your arms stretched out to the side and your hands flat on the floor.
Bring your right heel towards your left hand and tighten your right buttock.
Hold your left hip on the floor.
Repeat on the other side.
Make sure you keep your abdominal muscles tightened and keep breathing normally.
Keep your shoulders, upper body and feet on the floor and your knees together.