How to Do Leg Extensions to Build Strong, Sculpted Quads

illustration of the leg extension exercise with a resistance band around the ankles
Unlike squats, leg extensions isolate your quads, helping you build greater strength in these muscles.
Image Credit: LIVESTRONG.com

Want to squat stronger or climb stairs more comfortably? Your quads can definitely help with that. And one surefire exercise that'll build this big muscle group is the leg extension.

  • What are leg extensions?​ They're a seated leg-lifting exercise where you straighten then bend your knee against resistance, according to Carolina Araujo, CPT, a New York-based certified personal trainer.
  • What muscles do leg extensions work?​ This move focuses on the muscles across the front of your thigh, also known as your quadriceps or quad muscles.
  • Who can do this exercise?​ This exercise is safe for people of all ages. However, if you have any knee pain or mobility issues, it's best that you leave this move out of your workout routine.
  • Are leg extensions as good as squats?​ Like squats, leg extensions will strengthen your quads, Araujo says. But they isolate these muscles, whereas squats move multiple joints and muscles at once, building more strength across your entire lower body.
  • Can you do leg extensions at home?​ You can! You can do this exercise at home with no machine — all you need is a chair and a resistance band (more on that below).

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Ready to strengthen your quads with no gym machines? Here's all you need to know about this exercise.

How to Do Leg Extensions at Home

Resistance Band Leg Extension

JW Player placeholder image
Activity Resistance Band Workout
Body Part Legs
  1. Begin seated with a mini resistance band (Amazon.com, $10.95) looped around your ankles, both feet planted on the floor.
  2. Root your right foot into the ground.
  3. Raise your left foot toward the ceiling, straightening the knee.
  4. Reverse the motion with control and bring the foot back to the floor.
  5. Repeat the motion on the other side.

Tip

As you do this exercise, sit tall with your spine as flat as possible. If needed, you can swap for a chair that has a backrest.

3 Benefits of the Leg Extension

1. It Makes You Stronger in the Gym

The main benefits of the seated leg extension are increased quad muscle strength and size, according to Araujo. These muscles play a big part in the look of your legs but also help you in other exercises.

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Squats and lunges (to name a few) are quad-dominant exercises that demand a lot of strength of your legs. By building these muscles, leg extensions can help you better perform these moves.

2. It Improves Daily Movement

Aside from the gym, day-to-day motions, like walking, running or climbing stairs all use your quadriceps. Adding leg extensions to your workout routine will help make these daily tasks a little easier, Araujo says.

3. It Helps Prevent Injury

Your quads are responsible for helping your knees move and bend properly, according to the Cleveland Clinic. They also help keep your knee joint stable in your daily movement. But if your quads are weak, they limit the motion and strength in your knees, increasing your risk of injury.

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2 Common Leg Extension Mistakes

1. Using Momentum

If you find yourself swinging your legs while you do this move, you're probably not doing them with good form, Araujo says. When you use momentum, you take the work out of your muscles, so you don't build as much strength.

Fix It

Raise and lower your legs with as much control as possible. When you're using a leg extension machine at the gym (more on that below), increase the weight if you're unable to control your legs.

2. Locking Out Your Knees

Although you want to straighten your leg at the top of the motion, you should still maintain a slight bend in your knees, Araujo says. When you lock out your knees completely, you put unwanted stress on the joint, which can increase your risk of injury.

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Fix It

As you straighten your legs, pause the motion before you completely lock out your knee joint, she says.

Leg Extension Variation

Leg Extension Machine

Chances are, your gym has a leg extension machine available, which is a great option if you want to lift more weight, Araujo says.

You can use this machine by sitting on the seat and placing a padded lever across your shins, knees bent at 90 degrees. Using the pin on the side of the machine, adjust to your desired weight. Then, straighten your legs against the resistance of the lever.

As a leg extension modification, you can adjust the machine to shorten the range of motion, Araujo says. The more you bend your knees, the harder the exercise becomes. But you can tweak the machine to minimize how much you actually bend your knees.

2 Leg Extension Progressions to Add to Your Lower-Body Workout

If you're looking for other ways to make this quad-driven exercise more challenging, try these progressions.

1. Eccentric Leg Extension

Slowing down the lowering part of an exercise (the eccentric portion) can promote growth by keeping the muscle working (aka under tension) longer, according to the American Council on Exercise (ACE).

To increase the muscle-building benefit of this move, lower your leg for a 4-second count.

2. Double Leg Extension

Like the gym machine, you can also do this exercise at home with both legs, Araujo says. Swap your mini band for a long-loop band and anchor one end around the back legs of a chair. Place the other end of the band around your ankles and repeat the exercise, lifting both legs at the same time.

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