Lie on your front with your forehead rested on a small towel.
Keeping them straight, move your arms out to your sides and up a little so that they point diagonally up and away from you.
Rotate your forearms out so that your palms face forwards.
Keeping your chest and head in contact with the floor throughout, squeeze your shoulder blades together, and then lift your arms off the floor.
Hold this position.
Relax and repeat.