Home / The muscles of the legs / leg extension

leg extension

The leg extension, which can be translated by extension of the legs to the machine, is one of the best exercises of insulation of the quadriceps (front part of the thighs), at the same time simple and effective.

Its effectiveness comes from working in isolation, the movement made involving no other muscle. It does not require more very great strength and no particular technique.

Although secure thanks to the machine sitting position this exercise are not without risk. It places significant tension on the knees which can cause pain or injury when using heavy loads.

 The leg extension is recommended for beginners, and those wishing to preserve their back.

Why do leg extension?

For bodybuilding practitioners, the leg extension machine is one of the best exercises to develop and especially gives definition to the anterior part of the thigh (quadriceps). This exercise is also very important in rehabilitation, especially with light loads by working in full amplitude and maintaining the contraction for several seconds.

Unlike other exercises, it is a movement that solicits a single joint (monoarticular) and focuses only on the quadriceps. You will not have any assistance from your hips, glutes, or pistachios here. By targeting the quadriceps this way, you get a very high degree of localized intensity (deadly burning). Because your bust is supported, this exercise lends itself easily to one-sided work. By working one leg at a time, you can bring each quadriceps to total exhaustion.

(I see you as a person with an interest in bodybuilding! )
So I advise you of these products that you will need in this sport:

How to make the move?

Sitting on the machine, both thighs are in good contact with the seat. Place the bottom of the shins against the sleeves, so that, your knees are at an angle of 90°or more.

The back is straight or slightly leaning back and resting against the backrest. Grab the handles on each side of the seat to ensure your stability.

Inhale deeply and exhale while extending the legs. Hold the contraction for 1 or 2 seconds.

Breathe in slowly bringing the shins back almost to the vertical. Repeat the movement, taking care to keep the tension in the muscles all the time.

For balanced development, keep the toes pointed directly forward or slightly outward.

If you find it difficult to fully stretch your legs, lean as far back as possible, especially if the machine seat is tilted.

5 training tips

1 – Because the thighs are still during this exercise, there is a lot of pressures on the knees, which can be dangerous. To decrease this pressure, do not allow the shins to come back too far under the thighs (knee angle 90°or less) at the bottom of the movement.

2 – Full extension of the knees is important to achieve maximum contraction of the vastus internal and vastus external muscles. Their strength is crucial to keep the patella in place.

3 – Do not take too heavy loads: they prevent stretching of the legs completely and create excessive stress on the knee joint.

4 – Steep pistachios can hinder you to fully stretch your legs. In this case, lean as far back as possible to give these muscles some slack. Also choose a machine with a seat that is flat and not inclined, which will reduce the tension at the pistachios.

5 – To vary and get a little stronger contraction of the vast internal, turn the tip of the feet inward by stretching the legs completely. To put more emphasis on the outer vast, turn them outward.

What muscles are required?

Only one muscle is involved during the leg extension: the quadriceps, which are composed of four distinct beams having the same action. The right anterior, which is a relatively long muscle stretched in the middle of the thigh. A little smaller, but powerful, the crural muscle is located under the anterior right at mid-height of the thigh. The vastus medialis and the vastus externa are respectively located on the inner and outer sides of the thigh. These four muscles are inserted by a common tendon on the patella, itself fixed on the tibia.


Exhale when extending the legs. Inspire in a downward phase.


In unilateral or elongated

To vary the exercises, you can try to perform this movement unilateral, one leg at a time, or to practice the elongated leg extension if your room has such a machine.

To target the vast lateral or vast medial

We have seen that the leg extension solicits the quadriceps as a whole, but you can focus on one vast rather than another if a delay is felt. By pointing your feet inward, you will feel more the vast lateral (external), against the vast medial (internal) if you position your feet to the outside. As a beginner, no need to worry about such detail but with experience, this kind of adjustment can be valuable, especially in a competition goal where muscle balance is essential.

The sissy squat, a good alternative to isolating his quadricepsInteresting variant of the leg extension, the sissy squat also makes it possible to perform a work of isolation of the quadriceps. This exercise can be done with or without a machine.

 Think of the curl leg! 

We can not say it enough when we strengthen a muscle group, it is essential to work also antagonistic muscles. Thus, in parallel with the realization of the movement of leg extension, which makes it possible to solicit the quadriceps, think absolutely to strengthen your hamstrings, thanks to exercises such as leg curl. Too often, these posterior thigh muscles are neglected, which regularly causes knee injuries.

(I see you as a person with an interest in bodybuilding! )
So I advise you of these products that you will need in this sport:

Techniques for intensification of quadriceps work

The leg extension lends itself wonderfully to various intensification techniques, which can solicit a muscle to 100%. In this case, it is a question of optimizing the work of the quadriceps.

The leg extension in pre-fatigue

For the purpose of pre-fatigue, it will be necessary to perform a targeted muscle isolation exercise followed by a basic exercise in order to “tire” him to subsequently feel it better and solicit it. In the case of the leg extension, to target the quadriceps, you can realize your usual series, usually from 12 to 15 repetitions, then follow immediately with squat, which is the basic exercise must during your “leg day”.

Degressive series

The degressive series can intensify your session of the day with a goal of muscle growth. Here, you will perform your series with the leg extension until the failure then you will immediately drop the load of about 30% to start on new repetitions until the failure. If the heart tells you, you can again achieve a degressive series by decreasing by another 30% to push the work of the quads in their last retrenchments. Nevertheless, this technique is exhausting for the muscle and the nervous system. Use it wisely and not all of your exercises in one session.

Please follow and like us:

About Body@Building_Step

Check Also

Front Squat

When it comes to forging thighs of spartans, Squats often return to the mat. But …