HOW: While lying supine, bring both of your knees up and your feet flat on the ground. Place the slider underneath one foot. Push down into the slider with you heel as your straighten your leg all the way out. Keep the other bent and your hips on the ground. Keep driving your heel into the slider and then slide it back in.
FEEL: You should feel your hamstring muscles working. You should also feel your core working.
COMPENSATION: Don’t slide your leg out too fast, keep it controlled.