Matt Gemkow, the author of this content section at Select Fitness USA, boasts more than 15 years of fitness experience. He started out in sports and athletic training for many years and has since 2014 transitioned into heavy-weight training and bodybuilding. As a result, he has become one of the most experienced fitness equipment experts out there, and a valuable source of information.
Leg Press Vs. Leg Extension | What's The Difference?
You've probably heard of the leg press and leg extension exercises if you want to pump up those leg muscles and build a more muscular, massive lower body.
But which one is more effective? That's what we're here to find out.
In this article, we'll break down the differences between these two leg-busting exercises so that you can make the most of your leg day workouts.
So, let's dive in and see what the leg press and leg extension can do for you!
What is A Leg Press?
The leg press is a popular machine in the gym for its ability to safely and effectively mimic movements like the free-weight barbell squat.
It involves pressing a foot plate, loaded with resistance, with legs while seated or lying down on a machine.
The leg press is a compound exercise, meaning it works for multiple muscle groups simultaneously, Mostly the quads, hamstrings, and glutes.
One advantage of the leg press is that it allows you to easily overload the muscles involved in the exercise without compromising form and increasing the risk of injury.
This is because the machine takes some stress off your back and hips, allowing you to focus on and isolate your lower body.
There are different variations of the leg press machine, including the 45-degree leg press and the horizontal leg press. In another article, we go in-depth about the differences between all the types of leg press machines.
Overall, the leg press is an excellent exercise for building lower body strength, and size, by imitating compound free-weight movements like the squat, but with the assistance and stability of a machine exercise.
What is a Leg Extension?
The leg extension is another lower body exercise that targets the quadriceps muscles at the front of the thigh.
It involves using a machine to resist the movement of extending your knees.
The leg extension is great for targeting and isolating the quadriceps while leaving all other muscles out of the picture to train the one muscle group most effectively.
Additionally, it's a low-impact exercise, which makes it an ideal option for those who experience knee pain or discomfort with other lower-body exercises.
The leg extension machine has different variations, including Olympic weigh plate loaded machines and selectorized weight stack machines. Both perform the same exercise with an other way of resisting the range of motion.
The leg extension is an excellent exercise for building strength and size in the quadriceps muscles.
What is the Difference Between Leg Press and Leg Extension?
The main differences between the leg press and leg extension exercises can be summarized in a few main points.
First, the leg press primarily targets the quad, hamstring, and glute muscles, while the leg extension primarily targets the quads.
Second, the leg press places the user in a seated or lying position with the knees and legs in front of them, usually starting at around a 90-degree angle, while the leg extension places the user in a seated position, upright, with the legs bent and below them, as if they ae sitting in a chair like normal.
Third, the leg press range of motion involves the extension of the legs in three places; the ankles, knees, and hips. While the leg extension is focused on the extension (bringing the front of the foot forwards) of the knee joint.
Finally, the programming for each exercise differs, with the leg press often being used with heavier weight loads at a 6-15 rep range, while the leg extension is typically used with a lighter weight at a 10-25 rep range.
Let's dive a bit deeper into the differences of the two exercises and tell you everything you need to know to maximize both exercises.
Leg Press Vs. Extension Muscles Targeted
When it comes to leg day, it's essential to know which muscles each exercise you perform targets best and in what ways.
The leg press and leg extension are both exercises that primarily target the quadriceps, but they work in different ways.
Leg Press Muscles Worked
The leg press targets the quads, hamstrings, and glutes. When you perform a leg press, your quadriceps engage as you push the weight away from you.
Your hamstrings and glutes also work to help extend your hips and knees. The leg press is an excellent exercise for building overall leg strength and power.
Additionally, the leg press can be used in slightly different ways or positions to increase further or decrease the involvement of certain muscles.
Pro Tip: Change up the positioning of your feet to target different areas of your legs more prominently. We have a full Leg Press Foot Placement guide you should read.
Leg Extension Muscles Worked
The leg extension is an isolation exercise that primarily targets the 4 quadriceps muscles at the front of the thigh.
You move the weight by extending your knees when you perform a leg extension.
The starting position is seated with the legs below you as if sitting in a chair, and the user flexes their quads to extend the weight in front of them and straightens the knee joint.
Pro Tip: Rotate your Legs or change up which of the 4 quad muscles you hit the hardest. Rotate your toes inward to target the outer thigh, and rotate the toes outwards to target the inner thigh or tear drop of the quad.
Body Position Differences Of the Leg Press and Extension
When it comes to the body position differences between the leg press and leg extension machines, there are some notable distinctions.
The leg press machine requires the user to sit with their back against the backrest and their legs positioned at a 90-degree angle in front of them to start.
The legs are then extended at the ankle, knee, and hips to push the foot plate away from them and straighten the legs out. This is typically in a horizontal or incline orientation with a plate-loaded machine or selectorized weight stack machine.
On the other hand, the leg extension machine places the user seated with their legs relaxed and down in front of them as if they were sitting on a chair.
The extended position of leg extension exercise involves straightening the legs in the same seated position.
The ankles and hip joints are entirely static for the whole exercise, and the body's position remains the same other than the extension of the leg(s).
Biomechanical Range of Motion Differences
The biomechanical range of motion is another area where the leg press and leg extension exercises differ.
With the leg press, the user is pushing against resistance in a linear direction, whereas with the leg extension, the user is moving through a single joint range of motion.
This means that the leg press involves more muscle groups and a wider range of motion, while the leg extension targets a more specific, individualized range of motion to train that one muscle effectively.
Range of Motion of the Leg Press
Compound Movement: Involves multiple muscle groups and the use of multiple joints.
The range of motion of a leg press is similar to that of a barbell squat or deadlift.
The user is responsible for pushing a platform away from them, in a linear fashion majority of the time, with use and involvement of multiple muscles, muscle groups, and joints.
A leg press requires:
- Extension of the hips involves the glutes, hamstrings, and sometimes some of the lower back.
- The knee extension requires force from the quadriceps and is supported by the glutes and hamstrings.
- Use of the ankle joint. To a certain extent, the calf muscles may be active during a leg press, but the ankle joint 100% must be involved in the exercise as this is the point of contact to the footplate.
Range of Motion of the Leg Extension
Isolation Movement: Involves a single muscle group and a single joint.
The leg press range of motion is straightforward, requiring effort from just one muscle group, and involves the extension and flexion of just one joint.
When you extend your leg, you use the quad muscles to extend the knee joint, bringing your shin and foot forwards to straighten your leg.
This is the opposite of flexing your knee joint, which involves leg curl exercises.
Programming Sets and Reps for the Leg Press Vs. The Leg Extension
Programming sets and reps of the leg press and leg extension machine into your workouts will also be a major difference of the two exercises.
When it comes to how you utilize each machine or exercise in your workout, its the main difference, all else aside, of the two machines.
If you look at the nature of each of the workouts, leg press being a heavier compound exercise requiring more overall energy and the leg extension being focused on training one muscle and requiring less overall energy, its clear that they are used for different purposes.
It wouldn't make sense to start by targeting your quads and bringing them to full exhaustion to then hop on the leg press and try to do a bunch of weight...
Below we have detailed the specific use cases and target reps and sets for each leg press and leg extension machine.
Programming the Leg Press:
When to use it in a workout:
- At the beginning as the primary exercise of your leg day workout
- After a free weight compound exercise as a supplemental exercise
- As a light warm up in the beginning of any workout
- At the very end of a workout to burn out the legs
Ideal Set and Rep Ranges:
- Heavy: 3-5 Sets of 6-12 Reps
- Supplemental: 3-6 Sets of 8-15 Reps
- Light warm-up or finisher: 3-4 Sets of 10-25 Reps
Programming the Leg Extension:
When to use it in a workout:
- As a Leg Warmup
- During or after the Primary exercise as a supplement to the quads
- At the end as a quadricep burn-out finisher
Ideal Set and Rep Ranges:
- Heavy: 3-5 Sets of 10-15 Reps
- Lighter: 3-6 Sets of 15-25 Reps
Pros and Cons of the Leg Press vs. The Leg Extension
Leg Press Pros and Cons
- Targets multiple muscles as an overall leg exercise.
- Added safety and overloading ability with machine assistance and stability as compared to compound free-weight exercises
- Adjustability and compatibility for many people
- Easy to learn, and progress
- Hard to target individual muscle groups on their own
- Can be dangerous with too much weight or improper form
Leg Extension Pros and Cons
- Highly effective and isolated quad training
- Safe and less risk of injury due to poor form or too much weight
- Adjustability and compatibility to many people
- Very easy to learn and complete good form
- No hamstring or glute engagement whatsoever
- No direct benefit for, or correlation to, other exercises like the squat
Which is Better For Building Strength?
When it comes to building strength in the lower body, both the leg press and leg extension exercises are effective.
However, you could argue the leg press is generally considered to be better for building overall lower body strength, as it allows for heavier weights to be lifted and targets a larger number of muscles, including the quads, hamstrings, glutes, and calves.
The leg extension, on the other hand, primarily targets the quadriceps and may not be as effective for building overall lower body strength. It does however target more effectively the strength of the extension of the quads, which for some people, I.E. athletes, is very beneficial.
That being said, incorporating both exercises into your workout routine can provide a well-rounded approach to developing not only the quads but the full lower body.
What Happens if You Only Do Leg Extensions?
If you only do leg extensions on leg day, you may develop muscle imbalances and increase your risk of injury in activities like running, squats, deadlifts, and so on.
This is because the leg extension primarily targets the quadriceps, neglecting other important lower body muscles like the hamstrings, glutes, and calves.
Over time, this would lead to a weak posture chain which leads to other things such as poor posture.
Always give yourself a balanced and well round leg day workout plan that targets the quads effectively, as well as the other lower body muscles like the hamstrings, glutes, and calves!
Is Leg Press Bad for Your Knees?
The leg press is considered a safe exercise regarding your knees when performed correctly, with proper form and appropriate weight.
There are some instances, though, where the leg press may not be appropriate or may even increase the risk of knee injury.
If you have pre-existing knee issues, you should be very cautious with all leg exercises.
Additionally, if you perform the exercise with improper form, such as allowing your knees to cave in or extending your knees too far past your toes, you may put excessive stress on your knees and increase your risk of injury.
It's important to use proper form and weight, and to listen to your body if you experience any pain or discomfort during the exercise.
Are Leg Extensions Bad for Your Knees?
Leg extensions are not necessarily bad for your knees, but they can be if not performed correctly or with too much weight, similarly to the leg press and any exercise.
The knee joint can be put under much stress during this exercise, especially when the legs are extended fully.
To reduce the risk of knee injury, it is essential to use proper form, start with lighter weights, and gradually increase the weight as your strength improves.
It is also important to listen to your body and avoid pushing through any sharp or stinging pains or discomforts.
If done correctly, the leg extension is a very beneficial exercise for strengthening your knees!
Can the Leg Press and Leg Extension be Combined?
In fact, they absolutely should be.
Combining the leg press as a compound exercise and the leg extension as an isolation exercise is great for developing the quads and overall leg strength and size.
So, If You Had To Choose Just One, Which Is Better?
For the sake of the question, we have to say the leg press.
If you have access to only enough budget or space for one of the two leg machines, then absolutely go with the leg press. It will provide a more well rounded leg exercise and allow you to continue making leg progress.
If you are in a gym with both, use both. End of story.
Now that you know everything there is to know about the difference of the leg press and leg extension machines/exercises, you can get straight to leg gains!
Keep in mind the specific benefits and use cases of each machine and how you should use each one to your benefit.
Use the leg press as a compound exercise to target the lower body all around, and follow up with an isolated quadricep isolation exercise with the leg extension.