LEG CURLS - DONT HYPEREXTEND

179. LEG CURLS - DON T HYPEREXTEND Many of the older leg extension machines allow you to extend the legs past the locked-out position. In other words you can hyperextend at the knee joint. While you may be giving the hamstring muscles a better stretch, you are also forcing the knee joint through a greater range of motion than it was designed for. Try to keep your legs from locking out completely on leg-curl exercises.