Leg Extension
Also known as: Knee Extension · Quad Extension
Pure quad isolation, and the only common movement that fully loads the rectus femoris at short lengths.
- Primary
- Quadriceps
- Secondary
- —
- Equipment
- Machine
- Type
- Isolation
- Level
- Beginner
How to do it
Set up
- Adjust the seat so your knee lines up with the machine's pivot point.
- Set the ankle pad just above your feet, on the lower shin.
- Sit back into the seat and hold the handles.
Perform the rep
- Extend your knees until your legs are straight.
- Pause and squeeze at the top.
- Lower slowly to a full stretch.
- Keep your hips and lower back in contact with the seat.
Common mistakes
-
Swinging the weight up
Using momentum defeats the point of an isolation exercise. If you are bouncing out of the bottom, reduce the load.
-
Lifting the hips off the seat
Means the weight is too heavy. Stay seated and reduce it.
-
Cutting the range at the bottom
The stretched position is valuable. Let the weight come all the way down under control.
How to programme it
3sets
12–20reps
60 srest
A finisher, not a main lift. Take these close to failure: the fatigue cost is low and the quads respond well.
Variations
- Single-leg extension: fixes imbalances
- Paused extension: 2 s hold at the top
- Sissy Squat: bodyweight alternative with a big stretch
Frequently asked questions
Are leg extensions bad for your knees?
For healthy knees, no. Older concerns about shear force were based on studies of injured or reconstructed knees. If you have existing knee pain, reduce the range at the top and keep the load moderate.