Leg Extension
Extending the legs against resistance on a machine — isolates the quads through a clean, controlled range.
Also called: leg extensions, machine leg extension, quad extension
Illustrations: Exercise data by RepDB (repdb.co)
Setup
Sit in the machine with your back against the pad and the shin pad resting just above your ankles.
How to do the Leg Extension
- Extend your legs until they're straight, squeezing the quads at the top.
- Pause briefly without locking the knees out hard.
- Lower back down slowly to the starting position.
- Keep your back against the pad throughout — no leaning back to help the lift.
Leg Extension muscles worked
The Leg Extension works the quads.
Common Leg Extension mistakes
- Using momentum to kick the weight up.
- Letting the weight drop quickly on the way down.
- Arching the back off the pad.
Scale it
Easier: Lighter weight, or reduce the range slightly.
Harder: Pause 1–2 seconds at full extension each rep.
Pairs well with
Air Squat
The unloaded squat — the foundational lower-body pattern, used for warm-ups, circuits, and building movement quality.
Back Squat
The barbell squat — the heaviest-loadable lower-body strength lift, building quads, glutes, and trunk strength together.
Box Jump
An explosive two-foot jump onto a box with a soft landing — leg power and landing mechanics for stronger, springier strides.
Eccentric Step-Down
A slow-lowering step-down that emphasizes the eccentric phase — builds knee control and quad strength for downhill running.