How to Do Leg Extensions (5 Variations) – Illustrated Guide

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The leg extension is an isolation strength training exercise that targets your quadriceps. It involves extending your legs out to their full length, typically pressing against a padded bar on a leg extension lever machine.

Although leg extensions are usually performed on a machine, it's also possible to use a resistance band or free-weight dumbbells. In this guide, we explore 5 different variations you can add to your workout routine.

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Leg extensions vs other quads exercises

There are many exercises to choose from to target your quadriceps. The leg extension is an isolation exercise that specifically works your quads. This makes it different from squats, lunges and leg presses, which are all compound exercises, but which target your quads in one way or another.

But how do leg extensions compare to these exercises?

  • Leg extensions vs squats - The squat is a compound exercise, meaning it works multiple muscle groups at the same time. This includes your quads, glutes, hamstrings and lower back muscles. Squats demand good form and balance skill, which might be lacking for beginners. Leg extensions, on the other hand, are an isolation exercise that focuses entirely on your quads. This makes it an excellent choice for beginners looking to target and strengthen their quads.
photo - Man's legs showing large developed quads muscles
  • Leg extensions vs lunges - Lunges also target your quads, glutes and hamstrings. A major downside with the lunge is that it can put stress on your knees, particularly if performed with improper form. Because leg extensions allow for a controlled movement, there is less strain on your knees. This makes it a safer option if you are new to training or have knee problems.
photo - Woman performs leg extensions at the gym
  • Leg extensions vs leg presses - The leg press is another compound exercise that hits your quads, hamstrings and glutes. While leg presses are beneficial for overall leg development and functional strength, the compound nature of the exercise means your quads are not as targeted as in leg extensions. Another downside is that the leg press puts more strain on your lower back, particularly if performed with improper form. Because leg extensions are performed while seated, it is a safer exercise.

Quads muscle

Your quads (quadriceps) are the muscles at the front of your thighs. Their function is to straighten your knee from the bent position, and they help stabilize your knee joint. Your quads help in exercises like climbing, walking, running and jumping.

diagram - Showing the location of your quads in the front of your legs

Your quads are made up of four separate muscles - vastus lateralis, vastus medialis, vastus intermedius and rectus femoris. Each of these muscles originates from a different point on your femur and hip, and connect into a quadriceps tendon that attaches to your knee cap.

All variations of the leg extension target your quads muscles. Using a single leg extension allows you to develop one leg at a time, if you have a muscular imbalance.


Body weight seated leg extensions

illustration - How to do a seated leg extension

Leg extensions primarily work your quadriceps (quads) muscles. These are the large muscles in front of your thighs. As part of your workout routine, you can use this isolation exercise to strengthen your quads and improve your lower body strength.

In this variation, there is no additional resistance aside from your own body weight. This makes the exercise suitable for beginners just starting out on their fitness journeys. You can use this variation to practice the exercise and develop good form, before moving onto machine or dumbbell leg extensions.

How to do

  1. Sit on the edge of a chair or bench. Your feet should be flat on the floor. Hold onto the sides of the chair for support.
  2. Keeping your back straight and your chest lifted, extend one leg out in front of you.
  3. Hold for a moment at the top, then slowly lower your leg back down.
  4. Repeat for the other leg.

Sets and reps

To build muscle, aim for 3-4 sets of 8-12 reps. For endurance, you can increase the rep range to 10-15 reps.

Machine leg extensions

illustration - How to do machine leg extensions

Machine leg extensions is the most popular variation of this exercise. With the machine, you can adjust the weight to your level of strength, allowing you to easily increase the intensity of your workout.

How to do

  1. Adjust the machine to your height. Select a weight that is challenging but allows you to complete all sets and reps.
  2. Sit on the machine with your back against the padded seat. Your feet should be placed under the padded lever. Hold onto the handles for support.
  3. Extend your legs until they are straight.
  4. Pause at the top of the movement, then slowly lower back to the starting position.
  5. Repeat for the desired number of reps.

Single leg extensions

illustration - How to do single leg extensions

This variation focuses on one leg at a time. This can help you address imbalances between your left and right legs.

How to do

  1. Adjust the machine to your height. Select a weight that is challenging but allows you to complete all sets and reps.
  2. Sit on the machine with your back against the padded seat. Your feet should be placed under the padded lever. Hold onto the handles for support.
  3. Extend one leg until it is straight.
  4. Pause at the top of the movement, then slowly lower back to the starting position.
  5. Repeat for the desired number of reps, then switch to your other leg.

Resistance band leg extensions

illustration - How to do resistance band leg extensions

Unlike machine leg extensions, the resistance band leg extension does not require special gym equipment and can be done from anywhere, including at home. Resistance bands provide a different kind of tension compared to the machine. As you extend your leg out, the resistance increases, providing a unique challenge to your quads.

How to do

  1. Sit on a chair or bench.
  2. Loop a resistance band around one ankle and stand on the band with your other foot. Make sure there's some tension in the band before you extend.
  3. Extend your leg out in a smooth, controlled movement.
  4. Hold for a moment at the top of the movement.
  5. Finally, slowly lower back to the starting position.
  6. Repeat for the desired number of reps, then switch to your other leg.

Dumbbell leg extensions

illustration - How to do dumbbell leg extensions

The dumbbell leg extension is a more challenging variation. While both machine and dumbbell leg extensions are effective at targeting your quads, the dumbbell leg extension uses free weights. This demands more stabilization and engages more muscles than the machine exercise.

How to do

  1. Sit on a chair with your back firmly against the support.
  2. Hold a dumbbell between your feet, securing it with both ankles.
  3. Keeping your upper leg fixed, raise your legs up until they are extended out in front of you.
  4. Hold for the moment.
  5. Finally, lower back to the starting position.
  6. Repeat for the desired number of reps.

Tips

Progressive overload

If you are a beginner, start with a lighter weight until you master the proper form for the leg extension.

Gradually increase the weight as your strength improves over time. This increase puts greater challenge to your muscles and pushes your to its comfortable limits, which is an important part of progressing through strength and muscle gain workouts.

Avoid momentum

Avoid using momentum to lift the lever or dumbbell. Instead, focus on controlled movements on the way up and down.

Controlled movements ensure that the targeted muscles (your quads) are fully engaged through the entire range of motion. This ultimately leads to improved strength gains and muscle growth over time.