Lie face down on an exercise mat with your legs extended directly behind you, forehead in contact with the floor and hands holding either end of a long resistance front of you in a wide Y-shape. Your arms should be fully extended. Keeping both arms straight throughout the movement, slowly bring the resistance band up and over your head until its directly behind you. You should finish with the resistance band resting at the base of your spine. With control, reverse the movement to bring the resistance band back to the start position, maintaining that straight-arm position and locked out elbow throughout. As your mobility improves, work to reduce the width of your Y-shape, whilst still maintaining full range of motion for the exercise. Be sure not to compensate for lack of mobility in your shoulders by flaring your rib cage when performing the movement. Keep your rib cage down and squeeze your glutes. Repeat for the recommended amount of reps (or time).