How to Do the Machine Leg Extension
The machine leg extension isolates your quads by straightening your knees against a pad. It is a simple way to add quad volume without loading your back, useful for beginners, bodybuilders and anyone rebuilding leg strength.
Log every set of your Machine Leg Extension in Superlift
Muscles worked
Primary
- Quads
Secondary
- None to speak of
How to do the Machine Leg Extension
- 1
Sit in the machine and adjust the back so your knees line up with the pivot.
- 2
Place your shins under the pad, just above your ankles.
- 3
Grip the handles and brace your core.
- 4
Straighten your knees until your legs are nearly straight.
- 5
Squeeze your quads at the top.
- 6
Lower the pad slowly back to the start.
- 7
Keep your hips down on the seat.
Form cues to remember
- Squeeze at the top
- Lower slowly
- Hips stay down
- Don't swing the weight
Machine Leg Extension video tutorial
Common mistakes
Using momentum
Lower the weight and control both directions.
Lifting your hips off the seat
Adjust the seat and keep your hips down.
Locking out hard
Stop just short of locking and keep tension on the quads.
Dropping the weight
Take 2–3 seconds to lower each rep.
Sets and reps
| Muscle growth | 3–4 sets of 10–15 reps, 60 seconds rest |
|---|---|
| Endurance | 2–3 sets of 15–25 reps with a light load |
| Strength | 3 sets of 8–10 reps with a slower lowering |
Heavy leg extensions can stress your knees, so avoid jerking the weight. Use a controlled tempo and reduce the load if you feel knee pain.
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Track your Machine Leg Extension and watch it go up
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Machine Leg Extension FAQ
Are leg extensions bad for your knees?
For most healthy people, they are fine with controlled reps and sensible weight. If you have knee pain, use a lighter load or check with a professional.
What muscles do leg extensions work?
They isolate your quads, including the rectus femoris. They don't involve your glutes or hamstrings.
Leg extension vs squat?
Squats train many muscles at once, while leg extensions isolate the quads. Many lifters do both.
