HOW: Begin by lying on your back with a swissball underneath your feet/lower legs. Push into the ball with your feet lifting your hips up off of the ground. From here, continue to push into the ball as you roll it back towards your hips maintaining your hips off of the ground. Roll back to the starting position and relax.
FEEL: You should feel your hamstring muscles working.
COMPENSATION: Keep your hips up as you perform the hamstring curl.