Leg curls exercise the hamstrings, the muscles that run along the backs of your thighs. As well as firming and shaping your thighs, leg curls help with ordinary household chores and errands involving picking things up from the floor, including cleaning up after your kids or selecting items from the lower shelves at a supermarket. The hamstrings are actually composed of three individual muscles, the biceps femoris, the semitendinosus and the semimembranosus, which work together to bend your leg at the knee, to move your thigh backward and to prevent your knees from hyperextending. Because weak hamstrings can lead to knee instability, hamstring exercises such as leg curls can help prevent knee injuries.
Leg curls, like other strength-training exercises, should be done on two or three non-consecutive days each week. Warm up with 10 to 15 minutes of moderate intensity cardio before starting leg curls. Next, select a weight you can lift for eight to 12 repetitions with good form. According to the Mayo Clinic, a single set is sufficient for general fitness. As you become stronger, and find yourself able to complete 13 or 14 repetitions, increase the weight by 5 to 10 percent to continue to challenge your muscles. If you are performing compound leg exercises, such as deadlifts, squats, leg presses or Roman chair hyperextensions, do them before isolation exercises such as leg curls and leg extensions.
Seated Lever Leg Curl
Position yourself on a seated leg curl machine so that your back is flat against the backrest and your knees 4 to 6 inches in front of the edge of the seat. After adjusting the resistance, place your legs straight out in front of you with your calves on top of the roller or lever pad. Press your calves against the roller or pad as you bend your knees. When your knees reach a 90-degree angle, pause briefly and then straighten your legs gradually to return to the starting position.
Lying or Prone Lever Leg Curl
Since you lie face down on prone leg-curl machines, you should wipe down the machine or place a clean towel under where you will put your head before you work out, for both sanitary and aesthetic reasons. To begin your workout, lie face down on the machine with your knees extending a few inches beyond the end of the bench and your calves under the roller. Bend your knees up toward your buttocks and then return to the starting position. Use a steady controlled motion for best results; jerking the weight up and relying on momentum won't work your muscles as effectively through a full range of motion.
Cable Lying Leg Curls
You can perform prone leg curls using the low pulley on a cable machine. Place a bench perpendicular to the cable machine. Use ankle cuffs to attach your legs to the low pulley. Lie face down with your head pointed away from the pulley and your knees a few inches beyond the edge of the bench. Grasp to legs or front of the bench for stability and bend your knees until your feet point straight up to the ceiling. Straighten your knees gradually to return to the starting position.
- MayoClinic.com: What's Better for Strength Training — One Set or Multiple Sets?
- DrMirkin.com: How Muscles get Stronger
- MayoClinic.com: Strength Training: Get Stronger, Leaner, Healthier
- ExRx.net: Hamstrings Weakness
- ExRx.net: Thigh Exercise Menu
- ExRx.net: Lever Lying Leg Curl
- ExRx.net: Lever Seated Leg Curl
- ExRx.net: Cable Lying Leg Curl
- ExRx.net: Weighted 45-degree Hyperextension
- ExRx.net: Hamstrings
Carol Poster began writing professionally in 1974. Her articles have appeared in "Outdoor Woman," "Paddler," "Ski Magazine," "Women's Sports & Fitness," "Dance News," "Show Business," "The Athenian," "PC Resource" and "Utah Holiday," among other publications. Poster holds an M.F.A. in creative writing from Eastern Washington University, as well as a Ph.D. in English from the University of Missouri.