How to do it: Lie facedown on top of a Swiss ball so your back is flat and your chest is off the ball. Let your arms hang straight down from your shoulders, your palms facing behind you [A]. Keeping your elbows flared out, lift your upper arms as high as you can by bending your elbows and squeezing your shoulder blades together. Your upper arms should be perpendicular to your torso [B]. Without changing your elbow position, rotate your forearms up and back as far as you can [C]. Pause, then reverse the movement. If you can do more than 12 repetitions, use dumbbells.