Machine Leg Extension
Also known as: leg extension
- Secondary muscles
- Hamstrings
- Body part
- Upper Legs
- Position
- Seated
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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No other common movement isolates the quads the way the leg extension machine does: with the hips fixed and the pad at your shins, straightening the knees is the only way to move the weight. Squats and presses never fully load the final degrees of extension, and that top range is exactly where this machine earns its keep.
How to do the Machine Leg Extension
- Adjust the seat height and backrest of the machine to fit your body.
- Sit on the machine with your back against the backrest and your feet on the footpad.
- Grasp the handles or sidebars for stability.
- Extend your legs forward by straightening your knees, lifting the weight.
- Pause for a moment at the top, then slowly lower the weight back to the starting position.
- Repeat for the desired number of repetitions.
Tip: Point the toes slightly up and pause at the top of every rep.
Muscles worked
Primary
Quads · Legs
The quads straighten the knee against the pad and should feel a hard contraction at the top and a burn through the front of the thigh by the end of the set.
Secondary
Common mistakes
- Swinging the legs up — the weight should rise under control with a pause at the top, not kick up with momentum.
- Sitting too far forward — the knee should line up with the pivot point of the machine, so adjust the seat back until it does.
- Dropping the weight down — lower for three seconds and stop just before the stack touches to keep tension on the quads.
- Only doing partial reps — go to full lockout at the top and squeeze the quad hard for a count.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Muscle growth | 3–4 × 10–15 | 60–90 s |
| Endurance / finisher | 2–3 × 15–20 | 45 s |
| Strength | Not ideal — pick a compound lift for the same muscle | — |
Leg extensions go after squats or leg press as a quad accessory, or before them as a warm-up with light weight. Superset them with leg curls on the neighboring machine.
Variations and alternatives
Similar exercises
Without machine
Frequently asked questions
What muscles does the Machine Leg Extension work?
The Machine Leg Extension primarily works the quads. It also involves the hamstrings, which assist the movement and stabilise the joints.
Is the Machine Leg Extension good for beginners?
Yes. The Machine Leg Extension is rated beginner: it uses a machine and the movement is simple to learn. Start light, focus on the full range of motion and add load once every rep looks the same.
What can I do instead of the Machine Leg Extension?
If you cannot do the Machine Leg Extension, try the Seated Band Leg Extension. Each of them trains the quads through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Machine Leg Extension, a sensible starting point is muscle growth: 3–4 × 10–15 with 60–90 s rest; endurance / finisher: 2–3 × 15–20 with 45 s rest. Do it after your compound lifts. It is a finishing movement, not the main event.
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Exercise data and animations are licensed ExerciseDB content used in SetGrip. This page is for general information and is not medical or coaching advice.