How to Use the Leg Extension Machine for Quad Growth & Strength

The primary time you stroll into a brand new fitness center you in all probability discover a group of machines. You could by no means look their manner once more or they might be of curiosity to you relying in your aim and stage of expertise. The leg extension will get some hate for not being “purposeful” — sitting down whereas bending and straightening your knees will not be one thing it is advisable to do day by day.

However if you wish to develop huge quads, the leg extension can perform for that function. The power to isolate your quads on the leg extension machine is invaluable. It may be a fantastic addition to your program, particularly together with compound movements like squats, deadlifts, and lunges.

A person working out on the leg extension machine.
Credit score: Slatan / Shutterstock

Huge quads aren’t only for aesthetics. Constructing sturdy quads may also help you run sooner, soar larger, squat heavier, and learn to construct a mind-muscle connection as a newbie. Let’s get into the specifics of the leg extension — how and why to do it, what to keep away from, and different variations to strive — so you’ll be able to build eye-catching muscles with a function.

Editor’s Be aware: The content material on BarBend is supposed to be informative in nature, nevertheless it shouldn’t be taken as medical recommendation. When beginning a brand new coaching routine and/or food plan, it’s at all times a good suggestion to seek the advice of with a trusted medical skilled. We aren’t a medical useful resource. The opinions and articles on this website will not be meant to be used as analysis, prevention, and/or remedy of well being issues. They don’t seem to be substitutes for consulting a certified medical skilled.

Easy methods to Do the Leg Extension

Hop on the leg extension machine and prepare to develop your quads. Though the leg extension solely works your quads it’s nonetheless essential to interact your core, preserve correct posture, and create pressure via the remainder of your physique. 

Right here’s a step-by-step breakdown of find out how to management your physique and have interaction your muscle mass whereas supported by the machine for the leg extension.

Step 1 — Sit Tall to Set Up

A person sitting in a leg extension machine.
Credit score: Vladimir Sukhachev / Shutterstock

Regulate the peak of your seat so your legs are bent at 90 levels together with your decrease shins behind the pad. Sit again within the chair and maintain on to the handles by your sides. Retract your head. Pull your shoulder blades again and down. Draw your navel in direction of your backbone to interact your abs. Strive to not arch your again to keep up a impartial backbone.

Coach’s Tip: Preserve your again towards the pad and maintain the place earlier than beginning the motion. 

Step 2 — Lengthen Your Legs

A person extending their legs in the leg extension machine.
Credit score: Vladimir Sukhachev / Shutterstock

Inhale and brace your core. Exhale to increase your decrease legs till they’re parallel with the bottom. 

Coach’s Tip: Attempt to provoke the motion out of your quads to keep away from further stress in your knees. 

Step 3 — Decrease With Management

A person sitting in a leg extension machine.
Credit score: Vladimir Sukhachev / Shutterstock

Decrease your legs again to beginning place slowly with management. Resist the burden and gravity making an attempt to drag you down sooner. Preserve your backbone straight and core engaged.

Coach’s Tip: Keep away from urgent the backs of your knees into the pad when you decrease the burden down in the course of the leg extension.

Leg Extension Units and Reps

It’s essential to decide on your units and reps in another way primarily based on your goals so your muscle mass reply appropriately. For energy, consider heavier weight for fewer reps. Endurance coaching could have you lifting lighter for both extra reps or time. Hypertrophy will likely be someplace in between the 2. Listed below are a number of methods to program the leg extension to suit your objectives: 

  • For Muscle Mass: Carry out three to 4 units of eight to 12 reps. Go away one to 2 reps within the tank on the finish of every set.
  • For Power: Do 4 to 5 units of 4 to 6 reps at a heavy weight.
  • For Endurance: Do three units of 15-18 reps at a light-weight weight with minimal relaxation time.

Frequent Leg Extension Errors

The leg extension permits you to goal your quads with out stressing the remainder of your physique, so that you might be able to recuperate faster and accumulate extra quantity. To get essentially the most out of it, attempt to keep away from these frequent errors.

Arching Your Again

The seated place of the leg extension may also help shield your again, however you additionally want to interact your abs and management your backbone. It’s frequent to arch your again in the course of the leg extension as you focus your consideration and energy on the motion. 

A person using the leg extension machine.
Credit score: Vladimir Sukhachev / Shutterstock

[Read More: The Best Upper Back Exercises For Strength, Size, and Posture]

Concentrate on the place of your decrease again. If you end up compensating for a heavier weight by hyperextending your lumbar backbone strive going a bit lighter till you’ll be able to elevate with out arching your again.

Locking Your Knees Excessively

The leg extension could be a useful device for strengthening your knee joints however watch out to not add further stress by locking or hyperextending them on the prime of the elevate. Make sure you lift with a full range of motion and contract your quads laborious on the prime of every repetition, however don’t consciously give attention to snapping your knee joint into extension

Not Controlling the Descent

For those who’re going heavy or are reaching fatigue in the course of the leg extension there could also be a bent to drop your legs shortly after you attain the highest. As a substitute, attempt to management your descent as your legs slowly decrease again down in direction of the ground. 

Specializing in the eccentric a part of this train — or the lengthening of your quads — is integral for muscle hypertrophy. It could possibly additionally improve your bodily consciousness and your potential to maneuver heavier hundreds.

Leg Extension Variations

You will get lots of the quad-building advantages of the leg extension in a number of variations. You possibly can strive it together with your physique weight with progressions, go unilateral on the machine, or go for one other machine solely.

Body weight Leg Extension

You are able to do the leg extension with out the machine whereas seated in a chair. It is a nice choice for older of us or anybody who isn’t prepared for further resistance. You possibly can progress by including ankle weights

[Read More: The Best Foam Roller Exercises for Mobility and Better Movement]

You can too additional progress by standing up in the event you don’t want a chair. Stand in your left leg and draw your proper knee up till your proper leg is bent at 90 levels. Carry out body weight leg extensions together with your proper leg within the air after which repeat on the opposite facet.

Single-Leg Leg Extension

Persist with the leg extension machine for this one, however make it unilateral. You probably have any imbalances in your muscle measurement or energy, unilateral training may also help to even them out. Carry out leg extensions with one leg at a time to really feel the distinction.

Working one leg at a time on the leg extension permits you to commit most effort towards every rep, quite than letting your stronger facet choose up the slack of the weaker leg. 

Leg Extension Options

If the leg extension machine isn’t for you however you continue to wish to goal your quads, strive a few of these various lower-body compound actions. They will all be executed as bodyweight exercises or loaded with weights. 

You can too tweak every of those by altering the foot place or angle of your physique to be able to goal your quads much more. Your quads received’t be remoted however they’ll be working collectively and these essential movement patterns could make you stronger in on a regular basis life.


Studying to do a body weight squat is a superb various to the leg extension for rookies and older of us. Your quads will work to increase your legs however you’ll even be utilizing the remainder of your physique and studying to regulate your weight. While you’re able to progress, load it up for goblet squats with dumbbells or kettlebells, or transfer on to barbell back squats or front squats.

[Read More: The Split Squat Can Improve Mobility and Leg Strength]

In any kind of squat, focusing in your quads all through the whole elevate (or elevating your heels through weightlifting shoes) will assist get your quads into the sport. You can too take into consideration urgent your massive toe mound into the ground as you rise up; guarantee, although, that your total foot stays firmly involved with the ground and also you aren’t drifting onto your heels or fluttering up onto your toes. 


The step-up mimics the sample of strolling up a flight of stairs. This makes it a fantastic train and various to the leg extension for older of us. Additionally it is related for superior lifters since you’ll be able to step by step elevate the peak of the step to induce progressive overload.

To focus on your quads within the step-up, give attention to growing the peak of your step earlier than including weight. As you step, push into your massive toe mound to straighten your leg. You can be going via the movement of the leg extension by bending your knee as you step and lengthening it as you straighten. 

Bulgarian Cut up Squat

The Bulgarian split squat is a sophisticated unilateral exercise; think about it a development from a lunge. It’s a difficult various to the leg extension that may burn your quads to a crisp. You possibly can progress the Bulgarian by including weight or altering the elevation of your again leg.

You can too shift a few of the mechanics if you wish to goal your glutes or your quads: Leaning barely ahead and permitting your entrance knee to journey previous your ankle ought to apply a bit extra pressure to your quads as a substitute of your glutes.

Leg Press

For those who take pleasure in utilizing train machines on leg day however are open to different choices, think about the leg press. The leg press could not isolate your quads, however you can also make up for this by utilizing way more general weight.

For those who aren’t in a position to do lower-body compound actions exterior of machines, the leg press is an effective choice to get you working your decrease physique muscle mass and joints collectively on the identical time in one thing just like a squat sample.

Muscular tissues Labored by the Leg Extension

Though it’s essential to stabilize your full physique when doing this train, the leg extension technically solely works your quadriceps femoris muscle mass. Your quads’ major perform is to straighten your knee joint, however in addition they play into the way you stroll, run, kick, and soar. They will have an effect on your posture and assist stabilize your patella. (1)


Your quads include your rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius (therefore “quad”). Curiously, trendy anatomical analysis has revealed that there could also be a fifth compartment to the tissue, referred to as the tensor of the vastus intermedius (TVI). (1)

All sections of your quadriceps work to straighten your knee joint. Notably, your rectus femoris is biarticular; it crosses each your knee and hip joints. Because of this sitting again within the seat of the leg extension with an open hip angle could place extra stretch on that portion of your quads.

Working on the quads with the leg extension machine.
Credit score: Jasminko Ibrakovic / Shutterstock

[Read More: Active Stretches for Optimal Recovery & Performance]

Every part of your quadriceps contributes to completely different stability-related features round your femur, however for sensible functions, you’ll be able to consider your quads as one synchronous unit in the course of the leg extension — for essentially the most half.

Concentrating on Your Quads

Some fascinating knowledge has proven that you’ll be able to bias sure parts of your quads in the course of the leg extension by pointing your toes both inward or outward. An inward-pointing toe (which additionally creates inner rotation on the hip) could result in extra vastus lateralis activation, and vice versa. (2

Do observe that tweaking your method like this received’t drastically alter the consequences of the leg extension. It will not be price your time until you’re an intermediate or superior bodybuilder. 

Advantages of the Leg Extension

The leg extension is a quad-strengthening train with help from a seated place on the machine. Isolating your quads could have hypertrophy, energy, and joint well being advantages. 

Isolates Your Quads

The leg extension purely works your quads. It’s a single-joint motion of knee extension, which is the first perform of your quads. Isolation is nice for bodybuilders which can be searching for maximum muscle growth for aesthetics. The leg extension doesn’t tax your nervous system and physique like heavy squats do, thus making it simpler to recuperate from. 

Isolating your quads can even have strength-building advantages. In case you are trying to construct big-time leg energy it’s sensible to incorporate a wide range of leg-training actions quite than hammering away at one train indefinitely. 

Strengthens Your Knees

Since your quads perform to increase your knee and stabilize your patella, it follows that strengthening your quads can result in stronger knees. For those who’re new to train and haven’t discovered to interact your muscle mass correctly, particularly with free weights, the leg extension serves as a fantastic first step.

A person using the leg extension machine, with a coach checking his knees.
Credit score: Dragon Photos / Shutterstock

A leg extension is an effective place to purely strengthen your quads with the intention of enhancing your knees’ tensile capability, because you don’t have the added stress of supporting your physique weight throughout a free weight motion just like the squat or lunge.

Machines Are Accessible

Train machines catch some flak for not being “purposeful.” For those who’re somebody who sits loads at work it additionally will not be an optimum use of your restricted fitness center time to proceed sitting whereas exercising. However machines can really be a fantastic and secure choice for rookies or older of us who will not be comfy with free weights or performing workout routines on their very own.

While you use a machine just like the leg extension, you continue to must create pressure and preserve a great posture, however your stabilizing muscle mass don’t must work as laborious as they’d in a squat or lunge.

Lets You Practice Unilaterally 

The leg extension is supposed to be executed with each legs on the identical time, however it’s also possible to do a single-leg leg extension as a variation. Bodybuilders, as an illustration, can profit from this if they’re making an attempt to even out aesthetic imbalances of their quads, however the advantages don’t finish there.

A person in an orange shirt doing unilateral exercises on the leg extension machine.
Credit score: lunamarina / Shutterstock

For those who’re engaged on a sophisticated unilateral train like a pistol squat, you might discover that one leg is weaker than the opposite. Including in single-leg leg extensions may also help even out your quad energy. Or, in the event you play a sport that entails kicking like soccer, unilateral leg extensions can even assist hold each of your legs in preventing form.

Who Ought to Do the Leg Extension

The leg extension is a simple train that may assist construct muscle and energy in your quads. You probably have limited time in the gym and are in a position to do extra compound actions, it will not be price your time. For rookies, bodybuilders, and folks recovering from accidents, although, it may be a fantastic complement.


For those who’re brand new to the gym, studying to interact your muscle mass is simply as essential as rising or strengthening them. Isolation machines offer you an opportunity to hone in on the precise feeling of your quads working to increase your knees. You’ll be capable of take this with you as you progress into extra complicated workout routines.

A beginner using the leg extension machine.
Credit score: Vladimir Sukhachev / Shutterstock

[Related: The Gymgoer’s Guide to Whey Protein]

For older of us who might also be rookies, isolation machines just like the leg extension function accessible introductions to resistance coaching. The body weight variation executed in a chair may also be a fantastic choice; you’ll be able to work your quads with out having to help the remainder of your physique weight.


Bodybuilders can profit from the leg extension. They’ll be capable of do extra quantity at middle-range weights to stimulate progress and hypertrophy in their quads. Bodybuilders will typically do a number of accent actions throughout a leg exercise. Cap off your next leg day with the leg extension to take your quads to the brink with out worrying about full-body stability. 

If You’ve Been Away From the Gymnasium

Your quads play an essential position in extending your knees and stabilizing your patella. The leg extension can function a manner of rebuilding energy and muscle after a interval of inactivity. Make sure you seek the advice of together with your physician or doctor earlier than beginning any kind of train routine.

Construct These Quads

Functional fitness lovers could inform you to not waste your time on isolation machines just like the leg extension. Nevertheless, the leg extension might be helpful in case your objectives contain building strength and muscle in your quads. You possibly can incorporate leg extensions right into a program as an addition to extra sturdy workout routines that may hold you sturdy and ready for the bodily challenges of on a regular basis life.

For those who can’t or don’t wish to do the leg extension, the excellent news is you’ll completely work your quads via different workout routines like squats and lunges. However, in a pinch, if you’d like the help of the machine to pump out some quads positive aspects, hop on and provides it a strive.


Nonetheless have some questions on the leg extension? Let’s get some solutions.

Is the leg extension dangerous for my knees?

If executed appropriately and at an acceptable weight, the leg extension is under no circumstances inherently dangerous. Making use of mechanical pressure to any joint will create torque, and it’s the duty of your delicate tissues (as in, your muscle mass and tendons) to face up to that stress. So long as you observe good type and don’t push your limits too shortly, you have to be good to go.

Can I do leg extensions as a substitute of squats?

For those who’re bodily in a position to do squats, you must in all probability do squats. The leg extension solely works your quads, and in the event you’re trying to construct energy or muscle in your legs, squats will work all the muscle mass in your legs and train you to make use of them with out added help on the identical time.

I’ve a again damage, is the leg extension secure?

You probably have an damage, at all times seek the advice of together with your doctor earlier than beginning a brand new train program. The leg extension could also be secure for somebody with a again damage since you don’t want to face upright or load your backbone. That mentioned, you must nonetheless interact your core and shield your backbone within the leg extension.


  1. Bordoni B, Varacallo M. Anatomy, Bony Pelvis and Decrease Limb: Thigh Quadriceps Muscle. [Updated 2022 May 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.
  2. Stoutenberg, M., Pluchino, A. P., Ma, F., Hoctor, J. E., & Signorile, J. F. (2005). The influence of foot place on electromyographical exercise of the superficial quadriceps muscle mass throughout leg extension. Journal of energy and conditioning analysis, 19(4), 931–938. 

Featured Picture: Jasminko Ibrakovic / Shutterstock

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