Leg Curl Machine: What It Works & How to Use It

The leg curl machine, also called the lying leg curl, is a common gym exercise that helps improve physical performance and mobility, build muscle mass, and prevent injuries.

This exercise primarily targets the hamstring muscles, located at the back of the thighs. It also works the calves and glutes, contributing to overall lower-body strength and stability.

The leg curl machine should always be used under the supervision of a certified fitness trainer, who can recommend the correct form and weight based on each person’s physical condition and goals.

What it's used for

The leg curl machine is used to support physical rehabilitation, prevent injuries, improve mobility and performance, and promote muscle growth.

This is because the leg curl machine isolates the muscles at the back of the thighs, allowing for more focused strengthening of that area.

It can also help strengthen the calves and glutes to a lesser extent.

Muscles worked

The leg curl machine works the hamstring muscles located at the back of the thigh, including:

• The semitendinosus muscle, which controls movement in the hip and knee joints, helping with thigh extension, hip stabilization, knee flexion, and knee rotation;

• The semimembranosus muscle, which assists with knee flexion, hip extension, internal leg rotation, and hip stabilization;

• The biceps femoris, a long muscle at the back of the thigh that helps flex and externally rotate the knee and hip.

In addition to the hamstrings, the leg curl machine also works the gastrocnemius and soleus muscles in the calves, as well as the glutes.

How to use

To use the leg curl machine correctly, follow these step-by-step instruction:

1. Adjust the machine by selecting the desired weight and positioning the leg pad so that it rests just above your heels, with only your knees hanging off the bench;

2. Lie face down on the machine with your feet hip-width apart. Keep your core tight, your head aligned with your spine, and your shoulder blades drawn back and down;

3. Hold the handles to stabilize your torso and keep your toes pointed downward;

4. Exhale and bring your heels upward by bending your knees in a controlled motion toward your glutes, avoiding arching your back or lifting your hips;

5. Curl your legs until your knees bend beyond 90 degrees or until the pad nearly touches your glutes;

6. Inhale and slowly lower your legs back to the starting position in a controlled manner.

Try doing 3 to 5 sets of 6 to 15 repetitions, as recommended by a fitness professional.

Unilateral leg curl

The unilateral leg curl is performed one leg at a time. This variation can help correct or prevent strength or muscle imbalances between the two legs.

This happens because most people have a dominant side that tends to work harder during bilateral exercises.

Safety precautions

Important precautions when using the leg curl machine include:

• Avoid arching your back or turning your toes outward;

• Keep your abdomen, torso, and hips firmly against the bench during the entire movement;

• Do not drop your head toward the bench;

• Keep your spine stable and your core engaged throughout the exercise;

• Start with lighter weights and increase gradually;

• Stop the exercise and consult a doctor or certified trainer if you experience pain in your knees, hips, or back.

It’s also important to perform mobility exercises before using the leg curl machine to help prevent injuries. Examples include hip and ankle mobility drills and leg swings.