Why you need it: This exercise helps to connect the activation and mobility of your shoulder muscles to the movement of your entire body. It also improves balance and core stabilization, Richey says.
How to do it: Lie face down on top of a stability ball with the ball positioned under your belly button and pelvis, both legs extended out behind you, toes tucked under. If it's too hard to balance on the ball in this position, you can press your heels against a wall to help stabilize your body.
With your chest lifted off the ball (your spine should be slightly extended and straight) and your chin drawn into your chest, extend both arms overhead by your ears, making a 'Y' shape, thumbs facing up to the ceiling. Next, without moving your body, reach both arms straight out to the sides of your shoulders into a 'T' shape, palms facing down to the floor.
Complete the move with the letter 'A' by pressing your arms down and back by your hips, squeezing your shoulder blades together, keeping your thumbs to the ceiling, palms facing away from your body. Do two sets of 15 reps, taking a short rest by rounding over the ball in between sets.
If you want to make this move more challenging, you can add a set of light dumbbells, Richey says.