How to do a Leg Extension

Reviewed by JP Michelsen, CPT, B.A. Kinesiology

About Leg Extension

Sets Logged
5,270,193
Popularity Rank
12th
Difficulty
Beginner
Quads Strength
100 mSCORE 1st
Equipment Required
  • Photo of Leg Extension Machine
    Leg Extension Machine

Target muscles worked

Primary Muscles
Quads
Secondary Muscles
None

Instructions for Proper Form

Leg Extensions are an isolation exercise that target the quads. Due to a severe lack of isolation movements for the lower body, this is a great option for specifically targeting your quadriceps. The use of a machine restricts your range of motion, and adds some stability to the movement. This can help your focus more on exertion than stabilizing the movement. The downside to this exercise is that it places a lot of tension on your knee. Keep your weights light, and focus on pausing near the end of your range of motion.

  1. Sit upright in a leg extension machine while placing the lower back just above your ankles in front of your lower legs.
  2. Your knees should be flexed to 90 degrees and the back pad should be contact with your lower back and shoulders.
  3. Grab ahold of the handles for additional support.
  4. Extend your legs in an upward arc until your lower legs are aligned with your thighs.
  5. Return to the starting position.

Common Form Mistakes

  • Too Much Weight

    This exercise inherently places a lot of tension on your knee. Adding too much further increases your risk of injury. You can do this exercise safely by focusing on controlling the movement, and limiting your range of motion prior to fully extending your leg.

Weight & 1 Rep Max Calculator

Average Leg Extension standards by male, female, weight, age and height

Use this calculator to see Fitbod's possible first recommendations for you. This would be your starting line, based on more than 4.5 billion logged sets from 1.1 million users.

  • beginner
    8
    reps
    50
    lbs
    1 Rep Max
    65
    lbs
  • intermediate
    8
    reps
    60
    lbs
    75
    lbs
  • advanced
    8
    reps
    75
    lbs
    95
    lbs

Enter your stats to calculate your Reps & Weight

How is this calculated?

Alternative Exercises to Leg Extension

Filter By

  1. 1. Single Leg Leg Extension

    Photo of Single Leg Leg Extension being performed
    60.6 mSCORESWAPPED 8,938 TIMES

    Single Leg Leg Extensions is a variation of Leg Extensions that uses one leg at a time. Like other leg extensions, this isolation exercise targets your quadriceps. By targeting one leg at a time, you can focus your attention on getting good muscle activation in each leg. In addition, this can help you identify and address strength imbalances between legs. While leg extensions can be a great way to build strength and muscle mass in your quadriceps, they can also place a lot of tension on your knees.

    • Beginner
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  2. 2. Leg Press

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    99.7 mSCORESWAPPED 5,822 TIMES

    Leg Press is a compound exercise that primarily targets the quadriceps. The exercise itself is fairly similar to a standard squat, with some key differences. The biggest of these differences is the added stability from supporting your back on the Leg Press Machine. The end result of these changes is a more stable movement that further emphasizes your quadriceps. Leg Press is an excellent exercise for anyone looking to build muscle mass or strength in their quads.

  3. 3. Machine Leg Press

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    95.1 mSCORESWAPPED 4,172 TIMES

    Machine Leg Press is a variation on the more standard Leg Press. Like the Leg Press, this is a compound exercise that primarily recruits the quadriceps. This is a great exercise for building strength and muscle mass in your quads. The use of a machine doesn’t change anything significant about this exercise, although your positioning may change depending on the machine you’re using.

    • Beginner
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  4. 4. Dumbbell Lunge

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    97.6 mSCORESWAPPED 2,901 TIMES

    Dumbbell Lunge is a variation on the more standard Lunge. Similar to other Lunge variations, Dumbbell Lunge is a compound exercise that primarily targets the quads. The exercise itself is the same as a standard lunge except for the added weight from holding dumbbells in each hand. This is a great variation for anyone looking to make their lunges a bit more challenging without adding more complexity to the movement.

  5. 5. Dumbbell Squat

    Photo of Dumbbell Squat being performed
    94.1 mSCORESWAPPED 2,595 TIMES

    Dumbbell Squat is a variation of the more standard Squat. Like other variations, this is a compound exercise that primarily targets the quadriceps. The advantage of using dumbbells rather than a barbell is that you have more freedom in your range of motion which can make this a more accessible variation for anyone with mobility limitations. With that freedom comes a bit more instability with this exercise though, which can help you further improve your squat for, and build the strength needed for heavier, or more complex variations.

  6. 6. Air Squats

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    92.1 mSCORESWAPPED 2,065 TIMES

    Air Squats are a bodyweight variation of Squats. Like other variations, this is a compound exercise that primarily targets the quadriceps. Without any added resistance this is easily one of the most beginner friendly exercises out there. It’s a great way to start building strength, and working your way towards more advanced variations.

  7. 7. Back Squat

    Photo of Back Squat being performed
    99.3 mSCORESWAPPED 1,778 TIMES

    Back Squat is one of the three Powerlifting movements, and one of the most common lower body exercises. It’s a great compound exercise that can help build strength and muscle mass in your leg, especially your quadriceps. It’s a staple in most fitness programs, and is often used as a metric for tracking lower body strength in general.

  8. 8. Dumbbell Squat To Shoulder Press

    Photo of Dumbbell Squat To Shoulder Press being performed
    98.1 mSCORESWAPPED 1,453 TIMES

    Dumbbell Squat to Shoulder Press is a combination of a Dumbbell Squat and a Shoulder Press. Both pieces of this exercise are compound movements that primarily target the quads and shoulders respectively. Combining these two movements is more than just the sum of its parts. It’s a very functional movement that has tons of practical applications, especially for sports. It’s also a great starting point for anyone looking to build the strength and conditioning needed for more explosive exercises like Thrusters, or eventually Olympic lifts.

  9. 9. Lunge

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    90.8 mSCORESWAPPED 1,400 TIMES

    Lunges are one of the most common lower body exercises out there. It’s a compound exercise that primarily targets your quads. In order to return to a standing position with this exercise you need to engage your quads in order to push yourself back up. This further emphasizes your quadriceps compared to other Lunge variations, however this also places more tension on your knee. By stepping forward with a single leg taking most of the load, you can more easily identify, and address any discrepancies in mobility or strength between sides.

  10. 10. Seated Leg Curl

    Photo of Seated Leg Curl being performed
    98.8 mSCORESWAPPED 1,287 TIMES

    Seated Leg Curl is a weighted, isolation exercise that targets the hamstrings. Because a vast majority of lower body exercises tend to be compound movements, this exercise is a great way to isolate the hamstrings for building muscle mass, and developing strength. The use of a machine restricts your range of motion, and adds stability, allowing you to focus on exertion more than stabilizing the movement.