Movement:
Start in a plank position. Your body should form a straight line. Keep your legs wide for support and to prevent the hips from moving side to side as you perform the exercise. Brace your abs and engage the core by pulling your naval to your spine. Slowly and controllably raise your arm forward, performing a shoulder flexion. Slowly bring return to the starting position. Alternate arms and repeat. Your hips should not be moving as you perform this exercise.