How to do a Leg Extension
The leg extension isolates the quads by straightening the knee against a pad. Clean form keeps your back on the seat, reaches full extension with a squeeze, and controls the lowering. CalmArms grades range and tempo and counts each rep hands-free.
Muscles: Quadriceps (all four heads)
Demonstration: Leg Extension
How to do it with clean form
- 1
Sit with your back flat against the pad and shins behind the roller.
- 2
Extend your knees until your legs are straight, squeezing the quads.
- 3
Pause briefly at the top without locking harshly.
- 4
Lower under control — don’t let the stack drop.
Common leg extension mistakes CalmArms catches
Using momentum to kick the weight up.
Stopping short of full extension at the top.
Letting the weight slam down on the way back.
Lifting the hips off the seat to help.
How CalmArms grades the leg extension
Leg machines used to grade too generously; CalmArms now scores the leg extension on the same strict scale as everything else, so half and rushed reps show up in the grade.
Variations graded
Grade your leg extension on your next set.
Prop your phone and lift. CalmArms counts every rep and grades your form A–F, hands-free — on-device, no video uploaded.