If you don’t have a leg extension machine, weighted isolated extension of the knee is difficult to do.
If you search the web for leg extension alternatives, you’ll find article after article that just gives you quad exercises. Whilst they include excellent, effective exercises they don’t really replicate the leg extension particularly closely. The leg extension in the truest sense extends and flexes the leg at the knee, whilst minimizing hip extension and flexion.
This part is key.
As a certified personal trainer for almost 20 years I know it’s very difficult (almost impossible) to replicate this isolated movement pattern without a machine.
So the exercises here are going to be approximations of the leg extension to bring about similar results, not exact replicas. In this article, I’m going to show you the best leg extension alternatives, some of which need no specialist equipment whatsoever.
- What’s the problem with general leg exercises as a leg extension alternative?
- What muscles do leg extensions work?
- How to do leg extension alternatives without a machine
- Alternative way to load the quads without a leg extension machine
- Leg extension alternatives – the bottom line
What’s the problem with general leg exercises as a leg extension alternative?
The knee is a hinge joint, meaning it has two movements – ‘flexion’ (bending) and ‘extension’ (straightening).
In a leg extension machine, the movement is isolated at the knee – the hips and surrounding muscles don’t help the movement at all. This isolation of the quads is what makes leg extensions unique; lots of exercises use knee extension. Very few isolate the knee to do so.
In almost every other exercise involving the quads, the hips are engaged too. Whilst this is excellent from a strength and muscle building results point of view, it’s not truly a leg extension because the quads aren’t isolated.
In the alternatives I’ll suggest here, I’m going to try to reduce the involvement of the other muscles as much as possible.
For what it’s worth I think that unless you are doing them for rehab or bodybuilding ‘muscle isolation’ purposes, there are better quad exercises than the leg extension. We’ll discuss the functionality and the research as to why later in this article here.
What muscles do leg extensions work?
Leg extensions isolate the quadriceps muscles at the front of the thigh. This is a group of 4 muscles, including the:
- Rectus femoris (the main bulk of the muscle)
- Vastus medialis (the inner part of the thigh)
- Vastus lateralis (the outer part of the thigh)
- Vastus intermedius (in the middle behind the rectus femoris).
The activation of the quads varies depending on the range of movement during the exercise, as highlighted by this research from 2014. In the study, various foot positions and ranges of movement were used to assess muscle recruitment patterns. The overall results were…
- Vastus lateralis (outer thigh) activity increased towards the middle and end of the range of motion (the top two-thirds of the leg extension).
- Vastus medialis (inner thigh) was similar, but only as the set progressed. By the eighth repetition most activity was seen in the latter half of the movement.
- For the rectus femoris (main part), there was no difference in activation at any part of the ROM.
This means if you want to use the leg extension, adjusting the range of motion can have an effect on the muscle recruitment patterns and therefore results.
Word of warning though – there is very strong research showing that leg extensions load the anterior cruciate ligament throughout the range of movement. Oddly this decreases the faster the reps are performed (within reason).
It’s good advice then to avoid the leg extension (here’s how) if you have current or previous ACL issues and are not under the supervision of a qualified medical professional.
How to do leg extension alternatives without a machine
You may ask “how do I perform a leg extension without a machine?”
These exercises replicate the movement as effectively as possible, without resorting to exercises that are a million miles from a leg extension as per most other articles!
1. Dumbbell Leg Extensions
This is the closet replication of a machine leg extension you can do in a gym. It presents an extra challenge in that you have to engage the adductor muscles in order to hold the dumbbell between your feet. It’s limited therefore by the size and weight of the dumbbell you can grip.
An important coaching point here is to make sure your feet are off the ground when you have the dumbbell between them. otherwise, there’s too much hip flexor engagement.
An example of how NOT to set this up can be found here – she’s too low to the ground, so has to use her hip flexors to help lift the dumbbell off the floor. This puts too much pressure on the hip flexors and doesn’t isolate the quads very well.
Compare that to the above example where the lifter’s feet are off the floor when the lift starts and you’ll see the difference.
Equipment needed for dumbbell leg extensions:
- Incline bench/ plyo box
- Plate to lift the bench/box higher (optional – only use if required)
How to do a dumbbell leg extension:
- Set the bench to an incline and test the height – your feet should be off the floor when you sit on it.
- Hold the dumbbell between your feet and lift it off the floor.
- Extend the legs out quickly but smoothly.
- Lower to the start position under control.
- Repeat as many times as required.
Dumbbell leg extension muscles worked:
- Hip flexors (minor involvement)
2. Reverse Nordics
Reverse Nordics are a good alternative to leg extensions because unlike most other exercises, they really do isolate the knee as a point of flexion and extension. The hips, core, and torso remain tight throughout the movement meaning the quads do most of the work.
There is an abdominal control element through the movement as well, making it more functional. Finally, it’s an exercise that requires no equipment so it is very quick and easy to set up.
Equipment needed for reverse Nordics:
How to do a reverse Nordic:
- On a mat, kneel upright on both knees, keeping your body as tall as possible
- Push the glutes forward to engage the lower back
- Slowly lower yourself backwards until your quads are fully stretched
- Using your quads, pull yourself back to the starting position
- Repeat as many times as required.
Inverted rows muscles worked:
- Hip flexors
3. Plank Leg Extension
This is an exercise that won’t build huge muscle or strength, but it’s an effective high-rep exercise using limited kit. It also helps to isolate the quads fairly effectively, with an added shoulder and core stability element thrown in too.
The plank leg extension isn’t a well-known exercise but it certainly is an effective one. It doesn’t require much in the way of technique, but it certainly helps if you have a base level of strength – you’ve got to support your body weight throughout the exercise.
Equipment needed for plank leg extensions:
- Plyo box or bench to put your feet on
How to do plank leg extensions:
- Place your feet on the plyo box and your hands on the floor.
- Bend your knees and lower them towards the floor, keeping your back straight throughout.
- When the shins are parallel to the box, straighten your legs out completing the extension
- Repeat as many times as required (higher reps work best here)
Plank leg extensions muscles worked:
4. Backwards Prowler Push
This is a serious quad exercise and can be tweaked to emphasize strength or endurance by adjusting the weight. It requires a prowler and plates, but the movement is very similar to a leg extension without the need to use a leg extension machine.
It does require more space than a lot of people have, but if you have the room and equipment, this is an incredible leg extension alternative for you to include in your training programs. It removes most of the hip engagement and focuses mostly on the quads, just like a leg extension.
Equipment needed for backward prowler push:
- Prowler, space and plates
How to do a backward prowler push:
- Load the prowler with weight and lean backwards against the handles
- Drive the prowler backwards by pushing with the legs, keeping your back straight
- At the end of the length of the run, turn around and come back
Backward prowler push muscles worked:
5. Wall Sits
I’m not a massive fan of wall sits (mostly because I think they’re boring!) and they’re too easy to cheat on. That being said, when done properly, wall sits are a good leg extension alternative because they force the quads to work whilst removing most of the hip engagement.
It’s not an isolation exercise, but the static nature of it creates a lot of time under tension for the quads. If you do use wall sits in your training, they’re a good idea as a leg finisher, but don’t rely on them to build super strength or muscle.
Equipment needed for wall sits:
How to do a wall sit:
- Lean against the wall, making sure you don’t drop your thighs below parallel to the floor.
- Maintain the position as long as needed
Wall sit muscles worked:
Alternative way to load the quads without a leg extension machine
In the vast majority of cases, you’ll be using the leg extension to place more emphasis on the quads in order to make them stronger.
If that is your goal, there are safer ways that put less stress on the ACL (as discussed earlier).
One of the best ways I know of emphasizing the load on the quads whilst protecting the knees is with a slant board. A slant board is an angled board that is used to elevate the ankles during a squat, similar to a raised heel on a weightlifting shoe.
I’d recommend buying a slant board like this one for this.
You can see how to do a slant board squat in the short video below…
Research shows that slant boards improve quad muscle group activation (in particular the vastus medialis) whilst increasing the range of motion of the exercise. It also helps to reduce the size of the forces on the patellar tendon that runs over the knee, reducing injury risk. This also allows people with some knee problems to squat effectively.
You can find our popular 12-week beginner weight lifting routine here if you’re looking for a program to build muscle and strength safely.
Leg extension alternatives – the bottom line
The leg extension is a unique exercise in the sense that it’s a movement that is difficult to replicate exactly.
However, it’s possible to create the same effects in a slightly different (and arguably more effective) manner.
In this article we’ve covered leg extension alternatives, the effects of the exercise, and how tweaking the movement will bring about a different training effect. You’ll also know more about how the quads work and how to adjust the exercise to suit your training requirements and issues.
Looking for more quad exercises you can do from home? Check out our leg press alternatives for some better-suited exercises to work your legs.