Leg extension

Machine

Primary muscles

An isolation exercise for the quadriceps. Because the hip stays bent and does not extend, the rectus femoris works much harder here than in squats or leg presses.

Form cues

Align the knee with the machine's pivot
Squeeze at the top for a second
Control the lowering

Full leg extension guide →

What each muscle does in the leg extension

Muscle	Role	Action
Quadriceps	Primary	Extends the knee; the rectus femoris also flexes the hip

Primary muscles are the prime movers; secondary muscles assist or stabilise. The balance shifts with grip, stance, range of motion and technique.

Related exercises

Barbell back squat
Front squat
Conventional deadlift
Romanian deadlift
Walking lunge
Bulgarian split squat
Leg press
Lying leg curl
Barbell hip thrust
Glute bridge
Hip abduction
Hip adduction
Standing calf raise
Seated calf raise