How to Execute a Leg Curl

Control, posture, and ankle position is key to success

The leg curl is a basic isolation exercise the targets two primary muscle groups: the calf muscles (gastrocnemius and soleus muscles) and the hamstrings (the biceps femoris, semitendinosus, and semimembranosus muscles).

The leg curl is primarily a bodybuilding exercise used to increase muscle mass. It is not normally favored as an exercise for certain sports as it can cause the foreshortening (tightening) of the hamstrings as the muscles simultaneously grow and contract. As a result, flexibility can be impaired if the hamstrings are worked excessively.

Know Your Machine

The leg curl
microgen/Getty Images

The leg curl (also known as a hamstring curl) is executed on a gym bench with a levered lifting bar at the foot end of the machine. The exercise is performed lying flat on your stomach with your ankles tucked under a padded roller.

As you raise your feet toward your buttocks, cables connected to a system of pulleys smoothly lift the selected weight. As you lower your feet, the resistance is shifted, in part, to the buttocks (gluteus muscles), thighs (quadriceps), and front of the shins (tibialis anterior).

Newer ergonomic machines are angled so that hips are bent, placing less pressure on the lower back. There are also seated leg curl machines which operate under more or less the same principle.

Get Yourself in the Correct Position

leg curl
Getty Images

To start the leg curl, you will need to get yourself in the correct position and adjust the roller pad on the lifting bar.

Lying flat on your stomach, adjust the roller pad so that it rests comfortably on the back of the ankles just above the heels. You don't want the pads placed too high up on the calves as this can place undue pressure on the Achilles tendon and reduce the range of motion.

Choose the Right Weight

To properly execute a leg curl, always start with a lighter weight. What you don't want to do is have to yank the weight up by lifting the hips and flexing your lower back. This not only fails to isolate the calves and hamstrings, it can cause injury.

You should select a weight that allows you to do eight to 12 repetitions will reasonable effort.

If you want to build muscle mass, you would gradually increase the weight as you progress, To keep your hamstrings limber and avoid the lock-kneed bodybuilder's gait, always do warmup stretches before a workout.

If your aim is to increase power and performance, never overload the weights and be sure to counter the leg curls with leg extensions. Twice-weekly strength workouts are usually enough, particularly for runners.

Lift and Release With Control

Hamstring curl
Wikipedia Commons

The leg curl itself is pretty straightforward but requires you to focus on form throughout. To do a proper leg curl:

  1. Grasp the support handles lightly and lift your feet smoothly as you exhale, keeping hips firmly on the bench.
  2. Flex at the knee joint and pulls the ankles as close to the buttocks as you can.
  3. Hold for a second before releasing the weight with control. Do not let the weight drop. Inhale fully as you gradually return your feet to the starting position.
  4. Repeat the movement until you complete eight to 12 reps.

To a certain extent, you can target the hamstrings and the calf muscles by the movement of your toes. The hamstring can be targeted by pointing the toes (plantar flexion), while the calf muscle (gastrocnemius) can be isolated by dorsiflexing your foot (curling your toes toward the shin).