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Leg extension

The leg extension works your quads. Start with 2 to 3 sets of 10 to 15 reps, stopping with about 3 reps in reserve. To build muscle, do 2 to 4 sets of 10 to 15 reps.

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Video on the way

We film every move with real women. Until then, follow the steps and the 3 tips.

  1. Tip 1Knee lined up with the pivot
  2. Tip 2Pause 1 second at the top
  3. Tip 3Lower slowly

Where you should feel it

In the front of your thighs, your quads. A burn near the end of the set is normal.

Main muscles
Rectus femoris, vastus lateralis, and vastus medialis

How to do it

  1. Sit with your back against the pad, line up your knees with the machine's pivot and place the pad just above your ankles.

  2. Hold the handles and straighten your knees until your legs are almost straight.

  3. Hold for 1 second at the top, squeezing your quads.

  4. Lower slowly to near the start without letting the weight stack touch down.

Common mistakes

  • Mistake

    Knee out of line with the machine's pivot.

    How to fix it

    Adjust the back pad until the middle of your knee lines up with the pivot point.

  • Mistake

    Kicking the weight up and letting it drop.

    How to fix it

    Lift over 1 to 2 seconds and lower over 2 to 3. The lowering works your quads too.

  • Mistake

    Lifting your hips off the seat to move more weight.

    How to fix it

    Hold the handles firmly and keep your hips down. If they lift, the weight is too heavy.

Sets and reps for your goal

GoalSetsRepsReps in reserveRest
Getting started2 to 310 to 15345 to 90 s
Muscle and definition2 to 410 to 151 to 260 to 90 s

Reps in reserve: how many more reps you could still do with good form when you end the set.

Variations

Same movement, other equipment

  • Single leg

    One leg at a time on the same machine to even out both sides.

  • Seated with an ankle weight

    Sit on a high chair or bench and straighten your knee with an ankle weight on.

  • Resistance band

    A band tied to the chair leg and your ankle, straightening your knee against it.

At home or with more support

  • At home: seated knee extension with an ankle weight

    Sitting at the edge of a sturdy chair, straighten one knee at a time with the ankle weight and lower slowly.

  • Prefer more stability? Shorter-range leg extension

    On the same machine with a light weight, extend only halfway and lower slowly. You stay seated and supported.

Taken? Swap it for one of these

They work the same main muscle.

Keep exploring

Sources

  • Sets and reps

    Currier BS, D'Souza AC, et al. American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews. Med Sci Sports Exerc. 2026;58(4):851-872.

    Full textPubMedDOI

  • Muscles worked

    Ema R, Wakahara T, et al. Inhomogeneous architectural changes of the quadriceps femoris induced by resistance training. Eur J Appl Physiol. 2013;113(11):2691-2703.

    PubMedDOI

  • Technique

    Pedrosa GF, Lima FV, et al. Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths. Eur J Sport Sci. 2022;22(8):1250-1260.

    PubMedDOI

Review

Draft. This guide is waiting for review by a certified strength and conditioning professional.

Updated October 31, 2026