The Leg Curl Machine allows user to perform leg extensions to exercise the quadriceps. A leg curl is a piece of exercise equipment that isolates the hamstrings. It consists of a bench that the athlete lies on, face down, and a padded bar that fits over the athlete's heels. It is a piece of exercise equipment that isolates the hamstrings. It consists of a bench that the athlete lies on, face down, and a padded bar that fits over the athlete's heels. Leg Curl Machine allows people to comfortably and safely strengthen out the muscles on the back of the thighs.