Pilates - Hamstring Curl on a Ball

Nirbhay Singh of Ozone Fitness N Spa shows to do Hamstring curl on a ball exercise.  Lie down with your face upwards. Put your hands straight on the ground. Place your feet firmly on the ball and lift your bump. Throw your ball forward and back. When closer, lift your bump higher and when ball is away move your butt down. Lift one of your legs and throw the ball forward and back using one leg. Repeat this with the other leg. Repeat this exercise for eight to ten times. Relax slowly, Put both the legs on the ball and stretch your lower back. Slow down and then relax.