What is a leg extension?
You’ve probably seen the leg extension machine in the gym (even if you haven’t been on it). It’s a weights machine that you sit in, with a padded roller above your knees and another on top of your ankles. You flex at the knees to straighten your legs, which focuses all the work on your quadriceps muscles.
But you might be wondering how to do leg extensions properly, what muscles leg extensions are good for, and even if leg extensions are better than squats or lunges.
Commonly Asked Questions On Leg Extensions
What are leg extensions good for?
What muscles do leg extensions work?
Leg extensions work all four heads of your quadriceps muscles, and allow you to maintain tension on the muscles during the concentric contraction, the squeeze at the top, and the eccentric phase.
Is leg extension better than squats?
Leg extension machines hold your body in place, and pin your upper legs to the padded seat. You will usually have handles to hold, too, which prevents you swinging your body. This all means the leg extension movement is small and controlled (unlike a barbell squat or dumbbell lunge). And you’ll need to keep the weight light on a leg extension machine, which is safe for your knees.
Will leg extensions make your legs bigger? Yes, especially if you combine them with other exercises like squats, lunges, step ups, and leg press. Leg extensions are a great way to build lower body strength because they isolate growth in the quads.
What are the benefits of leg extensions
Leg extensions isolate your quads
The leg extension machine supports your back like a chair, and holds your upper leg and knee in place. This means you will isolate all the work in one or both quads so you can build strength and size.
You can do dropsets on the leg extension
Dropsets are a great way to add volume to your workout, and the leg extension machine makes it super easy to drop the weight through a triple dropset until you’re working to failure.
Leg extensions are a great finisher for leg day
Because leg extensions isolate the quads with a relatively light weight, they are a brilliant finisher exercise for lower body day workouts, and a good option for a lighter leg workout if you want to go running.
Leg extensions give you a good muscle pump
Getting a good pump isn’t everything, but it sure is rewarding! You will be able to see and feel the pump happening as you sit on the leg extension working your quads.
Leg extensions are safe for your knees
Leg extension exercises can a smarter choice than bigger compound movements like squats and lunges, because the movement is more controlled.
Are leg extensions OK for knees?
It might seem as though doing leg extensions could be bad for your knees, but the opposite it true for most people. In fact, leg extensions are such a safe exercise that they are often advised as rehab work after knee or quad muscle injuries.
Leg extension machines hold your body in place, and pin your upper legs to the padded seat. You will usually have handles to grip on to, too, which helps prevent you from swinging your body. This all means the leg extension movement is small and controlled (unlike a barbell squat or dumbbell lunge). And you’ll need to keep the weight light on a leg extension machine, which is safe for your knees.
When to avoid doing leg extensions
Whilst we think leg extensions are a safe, effective exercise, they aren’t always the best choice for your leg day programming. Here are the key reasons to steer clear of the leg extension machine.
You’re short on time
If you don’t have much time for a leg workout, stick to the big compound exercises with free weights (like barbell or dumbbell squats, lunges, or the leg press).
You feel any knee pain
It goes without saying that you shouldn’t jump on the leg extension machine if your knees are hurting.
You’ve already done a high volume leg workout
Leg extensions are best for light, reppy work to pump the quads, so if you’ve already achieved that in your workout there’s no need to do more.
How to do a leg extension properly
Once you start working out on the leg extension, use the handles to keep your body driving back and down into the seat. Lock your knees at the top of the movement, but don’t swing your legs up and down. Control the entire rep from start to finish.
Leg extension variations
Dropsets
Do 10-12 reps at a high weight, then quickly drop the weight to around 60% and do 10-12, then drop again to a very light weight and rep out until failure.
21s
Choose one weight and do 7 reps in the top half of your range, 7 reps in the bottom half, then 7 full reps.
Slow eccentric
Fast up, pause at the top, and lower down for a count of 4. This one will get real spicy, real quick! How long should you hold the leg extension at the top of the rep? Count 1-2 seconds before starting that controlled lower down.
