This static crunch helps develop core and hip stabilization.
How to do it: Lie with your hips, lower back, and shoulders in contact with the Swiss ball. Place your hands behind your head and pull your elbows back so that they're in line with your body. Lift your shoulders off the ball, looking down towards your legs. Brace your abs in tight as you slowly lift your left leg up to hip height, keeping your knee bent at 90-degrees, trying not to move your body. Lower your foot back to the floor and repeat on the other side. That’s one rep. Repeat 15 times total.