If you're struggling to grow or strengthen your quads with just squats and lunges, leg extension exercises can help. We share our top tips for getting the most of this exercise at the gym and at home.
- What are leg extensions? Leg extensions are an exercise where your thighs sit static on a chair while you extend your knees and raise a load toward the ceiling.
- What muscles do leg extensions work? Leg extensions primarily work the four muscles that make up your quadriceps on the front of your thighs: rectus femoris, vastus medialis, vastus lateralis and vastus intermedius.
- Can you do leg extensions at home? Yes! If you don't have access to a leg extension machine you can still perform this exercise using bands, ankle weights or small free weights.
- Who can perform leg extensions? Most people can perform leg extensions. They're easy for beginners to learn, and they're also useful for stronger, experienced lifters. However, if you have a history of knee pain or injuries you should consult your doctor or physical therapist before trying leg extensions.
- What's the difference between a leg extension and a leg curl? Leg extensions are an extension motion that targets your quads on the front of your thighs. Leg curls are a flexion motion, targetting your hamstrings on the back of your thighs.
Video of the Day
How to Do a Leg Extension With Good Form
Leg Extension
- Adjust the position of the machine seat so that your knees are in line with the fulcrum (the round piece that connects the lever to the machine).
- Align the lower moving pad to rest on the front of your shins and the upper support pad should lower until it places gentle pressure on your thighs.
- Initiate the movement by pressing up against the moving pad with your lower legs.
- Raise the weights until your legs are practically parallel with the floor.
- Finish the rep by bending your knees and lowering the weights all the way back down in a controlled manner.
Leg Extension Benefits
1. It Builds Your Quad Muscles
It's tough to truly isolate muscles because the human body is so interconnected (this is also known as the kinetic chain). Nevertheless, certain exercises can target specific muscles, while reducing the assistance of others. These moves can help strengthen weak links or grow stubborn muscles.
Leg extensions are one of the only movements that train your quads without also recruiting help from your glutes or hamstrings. They can help athletes who have difficulties growing or strengthening their quads with compound exercises like squats or lunges.
Strong quads can help you improve your performance at the gym. They're also important for other activities, like climbing stairs, hiking downhill and running.
Another bonus? It's also easy to use advanced muscle-building techniques with an extension machine, including drop sets and tempo training (more on that below).
Can You Do Leg Extensions Instead of Squats or Lunges?
Although isolation exercises, like leg extensions, can strengthen weaker spots, it's not a good idea to completely dismiss compound lower-body movements. These exercises target your quads along with your glutes, hamstrings, calves and core muscles.
Nearly all real-world movements involve a coordinated effort between multiple muscles and joints in your lower body. If you want to be strong and move well, you need to make sure compound exercises constitute most of your workouts. Isolation training is a helpful tool but it should not replace movements that train your body to work as a larger unit.
2. It's Accessible for New or Injured Athletes
The leg extension exercise is simple to learn and perform properly. This can make it a good fit for those who feel don't feel comfortable performing more complex exercises.
Isolation exercises, like extensions, are also often used to continue training around injuries. If you can't perform standing lower-body movements due to a hip, lower back or ankle injury, you can usually still train your quads using leg extensions.
Low-intensity leg extension variations can even be used to help rehab knee injuries according to a 2021 article in International Journal of Sports Physical Therapy.
Warning
Always consult with your doctor or physical therapist before trying a new gym machine.
Common Leg Extension Mistakes
1. Incorrect Set Up
As with all exercise machines, you need to adjust the leg extension to fit your body. If you don't, the exercise can feel uncomfortable, slow your progress and cause potential aches and pains.
Start by adjusting the seat so that your knees are in line with the fulcrum. This is the turning point of the lever, a round metal piece that sits close to the machine and connects the leg lever to the base.
Next, adjust the moving pad that sits on the front of your shins (right between your knees and ankles). Make sure the pad feels comfortable and doesn't sit way too high on your lower leg.
It's also a good idea to adjust the machine to use a full range of motion if you want to maximize your quad gains. Adjust the range so your legs move as far back underneath your body as possible in the bottom of the exercise. The only exception to this would be if a medical professional has instructed you not to bend your knees past 90 degrees.
Finally, make sure you lower the thigh support pad so that it prevents your upper leg from moving without placing uncomfortably high pressure on your legs.
2. Incomplete Range of Motion
Using a full range of motion helps recruit more muscle fibers and can maximize the strength and muscle gain you get from this exercise. This applies to both the bottom and top of your leg extension.
Set up the machine so that when you are sitting, your knees are bent past 90 degrees and your feet are as far back underneath your body as possible. Starting from this stretched position can lead to more quad development.
Push your legs up until they are almost completely straight (don't lock them out) and parallel with the floor. Do not hyperextend your knees by continuing to push your lower legs higher than your thighs. Some people like to do a 1- to 2-second pause at the top to make sure they're not selling themselves short.
If you have a history of knee pain or injury, you may want to intentionally use a reduced range of motion, according to a 2014 study in the Journal of Orthopaedic & Sports Physical Therapy. Force on your knees is lowest from 90 degrees of knee flexion to about 45 degrees of knee flexion during leg extensions, the study found.
Translation: You want to set up the machine so you begin with your knees bent at 90 degrees, then only press your legs up about 45 degrees.
Again, though, if you have sensitive joints or knee injuries, it's best to consult a doctor before you try any new exercises or gym machines.
3. Using Too Much Weight
It's easy to load up more weight than you can handle and muscle up your leg extensions using lots of body momentum. But do your best to avoid this, as it will hurt your results and place unnecessary strain on your joints.
Perform your leg extensions with a slow and controlled tempo. It's better to use less weight and stay honest with your form than to go fast or heave your body around.
Should You Go Heavy on Leg Extensions?
Some experienced trainees with healthy knees can eventually load their leg extensions with heavier weights. For most folks, however, lighter loads will feel better on their joints. In most cases, it's better to focus on using a slow tempo and a full range of motion before increasing the load. Save the heavy quad loads for squats, leg presses and lunges.
Leg Extension Variations
1. Eccentric Leg Extension
- Set up the machine properly for your body (more on that above).
- Initiate the movement by pressing up against the moving pad with your lower legs. Continue raising the weights until your legs are almost parallel with the floor.
- Finish the rep by bending your knees and lowering the weights all the way back down in a slow and controlled manner. Count 3 to 5 seconds on the way down.
Tip
Lower the weight as much as you need to control the speed and motion of the exercise. Slowing down and emphasizing the eccentric (lowering) portion of a lift can increase muscle damage, leading to greater muscle growth. It's also a good way to make an exercise more challenging without needing to use a heavier weight.
2. Single-Leg Extension
- Set up the machine properly for your body (more on that above).
- Initiate the movement by pressing up against the moving pad with one lower leg. Keep the other leg bent and relaxed beneath you. Continue raising the weights until your leg is almost parallel with the floor.
- Finish the rep by bending your knee and lowering the weights all the way back down in a controlled manner with one leg.
- Be sure to do all the reps on both sides.
Generally, everyone has a stronger side of their body. The single-leg variation of leg extensions is a great way to build unilateral strength. You can use this exercise to help improve muscle imbalance between your two legs.
3. Standing Cable Leg Extension
- Attach an ankle cuff to a cable pulley set at about hip height. If you don't have a cuff, you can also use a single soft handle. Secure the cuff to your ankle, or slide your foot through the handle.
- Stand in front of the cable machine, taking a few steps away. You can hold onto the machine for balance as needed.
- Begin with the weighted side knee bent and your foot back behind by your body. Initiate the movement by pushing down and forward with your foot until your knee is almost straight.
- Finish the movement by bending your knee and raising your foot back behind you in a controlled manner.
- Be sure to do all the reps on both sides.
4. Resistance Band Leg Extension
- Attach one end of a long-loop resistance band to a sturdy object. Sit on a chair or bench out in front of the anchor with the other end of the band looped around your ankles.
- Initiate the movement by pressing up against the band with your lower legs.
- Raise the band until your legs are almost parallel with the floor.
- Finish the rep by bending your knees and lowering the band all the way back down in a controlled manner.
5. Mini Band Single-Leg Extension
- Sit on a chair or bench with a mini band looped around your ankles.
- Initiate the movement by pressing up against the band with one leg. The other leg should stay in position beneath you. Continue raising the band until your leg is almost parallel with the floor.
- Finish the rep by bending your knee and lowering the band all the way back down in a controlled manner.
- Be sure to do the reps on both sides.
No exercise machine? No problem. You can use an ankle weight to mimic a leg extension machine right at home.