Seated Leg Extensions to Strengthen Your Quadriceps
Movement card
| Body area | Legs and ankles |
|---|---|
| Also called | seated leg extensions, seated knee extension |
| Works | quadriceps |
| Type | Strength |
| Position | Seated |
| Hold | 1 to 3 seconds |
| Reps | 8 to 12 |
| Sets | 1 |
| Sides | Each side |
| How often | Once or twice a day, especially during long periods of sitting. |
| Equipment | Chair |
| Office visibility | Low |
Seated leg extensions are a strength exercise you can do right in your office chair. The movement involves straightening one leg at a time to engage the muscles on the front of your thigh.
This exercise is helpful for people who sit for long periods. It can activate thigh muscles that may become inactive during the workday.
What the seated leg extension works
This exercise primarily targets the quadriceps, which are the large muscles on the front of your thighs. Engaging these muscles helps to support the knee joint. You are using your own body weight to create resistance.
How to do it
Starting position: Sit tall in your chair with your back supported. Place your feet flat on the floor with your knees bent at a 90-degree angle.
- Brace your core muscles to keep your back straight and still.
- Slowly extend one leg out in front of you until your knee is straight but not locked.
- Squeeze the large muscle on the front of your thigh.
- Hold this position for a moment.
- Slowly and with control, lower your foot back to the starting position.
- Complete all repetitions on one side before switching to the other leg.
What you should feel
You should feel the muscles at the front of your thigh working as you lift and hold your leg. The sensation should be one of muscle engagement, not pain. You should not feel sharp pain in or around your kneecap.
Common mistakes
- Swinging the leg up with momentum instead of using muscle control.
- Locking the knee joint at the top of the movement.
- Leaning back or slouching in the chair.
- Moving too quickly through the exercise.
Make it easier or harder
- Easier: Do not extend the leg all the way.
- Easier: Perform the movement without holding the top position.
- Easier: Do fewer repetitions.
- Harder: Hold the extended position for longer.
- Harder: Slow down the movement, especially when lowering the leg.
- Harder: Add a light resistance band around your ankles.
Fitting it into a desk day
This is a discreet exercise that you can do under your desk anytime, even during calls or meetings. It is a quiet way to activate your thigh muscles when you have been sitting for a long time. You can fit in a set between tasks without leaving your chair.
Quick questions
How long should I hold a seated leg extension?
When your leg is extended, hold the position for a moment, between one and three seconds, before slowly lowering it back down.
What are common mistakes to avoid?
Avoid swinging your leg with momentum or moving too quickly. Keep your back straight and supported in the chair, and do not lock your knee when you extend your leg.
How can I make seated leg extensions harder?
To make the exercise more challenging, you can hold the extended position for longer. You can also slow down the movement, especially when lowering your leg.
When to see a doctor or physio
Stop this exercise if you experience any of the warning signs listed for this movement. If pain continues after you have stopped, consult a doctor or physical therapist for guidance.
- Sharp, shooting, or sudden pain in the knee.
- Painful clicking or popping in the knee joint.
Skip it or ask first if:
- You have a recent knee injury or have had recent knee surgery.
- You have knee pain that worsens with this movement.
How this page was put together: general guidance consistent with public workstation and movement-break resources from OSHA, CDC/NIOSH and the NHS, and with standard exercise handouts. It was drafted with AI assistance, checked in a separate review pass and edited under our editorial policy. It is not medical advice and no clinician reviewed it. Last checked October 2026.