How To Do Leg Extensions
What is a leg extension?
See all leg extension variations
Leg extensions are an isolation exercise targeting the quads. This exercise is typically carried out on a leg extension machine, but there are banded alternatives which can be done outside of the gym.
If your goal is to improve the strength and size of your quads, leg extensions can be really helpful to include in your workout. While compound exercises like squats are great at building power, isolation exercises allow you to really hone in one a specific muscle and train it to failure, which can speed up gains. Leg extensions in particular are a great way to finish off a workout, or pre-exhaust your quads at the beginning of a workout.
Isolation exercises can also help if you struggle with muscle imbalances. For example, if you have weak quads, you may find your hamstring and glutes take on more load in compound moves. In this scenario, you can use leg extensions to build up strength in the quads to prevent this from happening.
Commonly asked questions on leg extensions
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Leg extensions are a safe exercise when performed correctly. However, it's important to use a weight that is challenging but manageable and prevent your knees from over extending during the movement.
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Focusing on form over weight is crucial with leg extensions. Going too heavy poses a greater risk of injury. Even without this risk, choosing a weight that is too heavy means you're more likely to rely on momentum rather than muscle to move the pad. Opt for a weight that is challenging but still allows you to do a controlled, smooth leg extension.
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The exact number of reps and sets you should do leg extensions for will vary depending on your goal. A good number to aim for is 3 sets of 8-12 reps. As you reach the top range of these reps, increase the weight to make it more challenging.
Leg extension tips
- When setting up the leg extension, make sure your knee is at a 90 degree angle. Anything less than this can irritate the knee joint.
- Select a weight that allows you to extend the leg straight in a controlled manner. If you are struggling to straighten your legs, drop the weight.
- Hold on to the bars at the side of the machine. This will increase stability and ensure that your quads are doing the hard work!
How to do a leg extension
Level: Beginner to Advanced
Equipment: Leg extension machine
- Adjust the machine so that you can sit with your back flat against the support and your knees bent at 90 degrees. The leg pad should in front of the top of your ankles, feet facing forward.
- Grip the bars on either side of the seat.
- Use your quads to extend your legs up until they are fully straight.
- Hold this position for a second and squeeze your quads before slowly lowering your legs back to the starting position.
How to do a single leg extension
Level: Beginner to Advanced
Equipment: Leg extension machine
- Adjust the machine so that you can sit with your back flat against the support and your knees bent at 90 degrees. The leg pad should in front of the top of your ankles, feet facing forward.
- Grip the bars on either side of the seat.
- Keep your left leg at a 90 degree angle while using your right quad to extend this leg.
- Hold at the top before slowly returning to the start.
- Repeat for your full reps before switching legs.
How to do a banded leg extension
Level: Beginner to Intermediate
Equipment: Chair, resistance band
- Sit on a chair with your legs flat on the floor, knees bent at a 90 degree angle.
- Wrap one end of the resistance band around your left foot, so you are standing on the band, and wrap the other end around your right ankle.
- Place your hands on the sides of your right thigh, or grab the sides of your chair and pull your weight into the chair. This will help to keep your quads stable.
- Squeeze your quad and straighten out your right leg until it is fully extended.
- Pause before slowly returning to the starting position.
- Repeat for the desired reps before switching legs.
If you’re not sure if any of the above exercises are suitable for you, please consult your doctor before you start it. Need guidance on how to perform the exercise? Ask a personal trainer at your gym.