Start in a 4 point kneeling position, with your hands under your shoulders and your hips over your knees.
Keeping your elbow bent to 90 degrees, lift one arm up towards the ceiling.
Hold briefly and then bring this arm down and across your chest, keeping your elbow bent to 90 degrees.
Keep trunk still and stable, only allowing the arm and shoulder to move.
Repeat for required number of repetitions.
