Completing Swiss ball hamstring curls are a good way to improve your hamstrings. To complete this exercise, put your feet on a Swiss ball, so that your heels are in a stable position on the ball, then lift your body off the floor and form a straight line from your shoulders to your feet. Then proceed to roll the ball towards your body by bending your knees. Hold the position for a few seconds then roll the ball out again and repeat the movement. This particular exercise will exercise your hamstrings and also works your core due to the unstable surface of the Swiss ball.