How to Do Leg Curls: Proper Form, Variations, and Common Mistakes

Lying leg curls (also known in the short form, leg curls) is an isolation exercise that targets the back of the leg: the hamstrings and calf muscles. It can be performed in a variety of positions and makes an excellent addition to most any lower body strength training workout.

How to Do Lying Leg Curls

Lie face down on the lying leg curls machine, stretching your legs out fully. The roller pad should rest just above the heels, a few inches over your calves. Grasp the support handles on each side of the machine.

1. Exhale and flex your knees, pulling your ankles as close to your buttocks as possible. Keep your hips firmly on the bench.
2. Hold briefly.
3. Inhale as you return your feet to the starting position in a slow and controlled movement.

Benefits of Leg Curls

Leg curls target the hamstrings (biceps femoris, semitendinosus, and semimembranosus) and calf muscles (gastrocnemius and soleus muscles). When lowering your feet back down, your buttocks (gluteus muscles), thighs (quadriceps), and front of the shins (tibialis anterior) are activated too.

Strong, flexible hamstrings are essential for overall strength, balance, and stamina. Research has also connected hamstring strength with better sports performance, particularly sprint-based training and movements.

Strong hamstrings aren't just beneficial in the gym. Conditioning these muscles can also help you avoid injury in day-to-day activities involving your lower body use. This includes playing with kids, completing household chores, yard work, and more.

Strength and flexibility in this muscle group will also help as your body ages—especially if you are prone to knee problems or have joint or back pain.

Other Variations of Leg Curls

You can perform leg curls in a variety of ways to better meet your skill level and fitness goals.

Standing Leg Curl

Beginners may want to do leg curls while standing. Standing leg curls requires less hamstring strength because you do them without weights.

To do standing leg curls, stand with feet hip-width apart. Shift your weight onto one leg and bend the other at the knee, bringing that foot closer to the butt. Lower the foot and repeat on the other side.

Standing Leg Curl With Resistance Band

Adding a resistance band to your standing leg curl is one way to build strength in the hamstrings and calves if you don't have access to gym equipment. Place the band just above the ankles and lift your foot against the resistance.

Seated Leg Curl

You may prefer the seated leg curl variation if it is uncomfortable to be in a prone position or if you have lower back or neck pain. The other benefit to seated curls is that the machine's design prevents you from lifting your legs as you curl.

When doing seated leg curls, the thigh pad should rest just above the knees and the lower leg pad directly below the calf. While grasping the machine's handles, push down on the lower leg pad, pulling it as close to your butt as you can. Hold, then return to the starting position.

Nordic Hamstring Curl

What sets this curl apart is that, instead of keeping the body stationary and only moving the lower leg, the Nordic hamstring curl keeps the lower leg stationary as you move the rest of the body. Research connects Nordic curls with the reduced risk of a hamstring injury.

This variation involves kneeling on the floor, placing the ankles under an immovable object (or having someone hold them), and then leaning forward at the knee. Because you must control your body's forward lean, this curl requires more core muscle strength than the other variations.

Common Mistakes

Avoid these mistakes when doing leg curls to keep this exercise safe and effective.

Leg Pad Too High

If the padded lever is too high on your calves, this can place pressure on your Achilles tendon and reduce your range of motion. The first time you try leg curls, you may want to have a trainer or fitness instructor show you the correct position and help you adjust the roller pad if needed.

Not Using the Right Weight

To properly execute a leg curl, always start with a lighter weight. You don't want to force your body to overcompensate by lifting the hips and flexing your lower back. This fails to isolate the calves and hamstrings and can cause injury to your back.

If you want to build muscle mass, gradually increase the amount of weight as you get stronger. However, keep in mind that if your goal is to increase power and performance, you don't want to overload the weights.

Safety and Precautions

Bodybuilders use hamstring curls to increase muscle mass. However, fitness pros and athletes who play certain sports don't always favor the exercise as it can cause the foreshortening (or tightening) of the hamstrings.

Repeated contraction and muscle growth can impair hamstring flexibility if you overtrain and fail to stretch correctly. To keep your hamstrings limber, always do stretches after your workout.

Some people may want to avoid leg curls entirely because this exercise could exacerbate an existing problem, slow healing, or put you at risk for increased pain. This includes people who:

• Are recovering from injury or surgery involving the back, spine, or neck
• Have injuries or instability in the knee
• Have recently had knee or hip surgery
• Have ruptured or torn ligaments in the knee or ankle, such as your Achilles tendon or anterior cruciate ligament (ACL)

As always, talking with your doctor before starting a weight training program is best. If you work with a physical therapist or trainer, check with them for guidance on using the leg curl machine and whenever you feel ready to increase weight. Aim to complete three sets of 8 to 12 reps.

Try It Out

Incorporate this move and similar ones into one of these popular workouts:

• Lower Body Strength Training Workout
• Strength Circuit Workout
• Lower Body and Core Workout