5. Hamstring curl
Lie on your back with your knees bent, feet flat on the ground and the ball just in front of your feet. Place your heels on top of the center of the ball, and find your balance. With your hands on the ground next to your sides for support, tighten your core, and lift your hips off the ground until your body forms a straight line from heels to shoulders. From this position, press your heels into the ball, engage your glutes and hamstrings, and bend your knees, drawing the ball toward your hips. When you’ve pulled it close to you, reverse the movement, keeping your core tight and straight, and extend your knees, rolling the ball away from you.
Works: Hamstrings, glutes, core
6. Unstable shoulder press
With a dumbbell in each hand, sit on the stability ball as if it were a chair, your torso straight and tall. Place your feet flat on the floor with your knees bent at 90 degrees. Raise the dumbbells to your shoulders, your palms facing away from you and your elbows bent. Press your shoulders straight over your head, extending your elbows. Reverse the movement, and lower them steadily back to your shoulders.
Works: Shoulders, biceps, triceps
7. Unstable triceps skull crushers
Holding a dumbbell in each hand, sit on the ball as if it were a chair, and then begin stepping your feet forward, allowing the ball to roll up your back. When the ball is between your shoulder blades, engage your core, and press your hips to the sky, positioning your heels under your knees (bent at 90 degrees) so you’re using the ball as a bench.
Press the dumbbells straight over your chest with your arms extended and your palms facing inward. From this position, keep your upper arms fixed, and bend your elbows, lowering the dumbbells toward your forehead. Just before the touch, reverse the movement, engage your triceps and press the dumbbells up to start.
Works: Triceps, shoulders, core
8. Stability ball pikes
Using the same positioning you used when performing the unstable pushups, check your form to make sure your palms are directly under your shoulders and your body is forming a straight line from heels to head. This time, position the ball on your calves rather than higher on your legs.
Engage your core, press through your palms and the tops of your calves and feet, and draw your hips straight up to the sky, hinging at the shoulders as you draw the ball toward you so you enter a supported pike handstand. Carefully lower your hips, and return to start.
Works: Core, chest, shoulders, quads