Exercise guide
Weighted Seated Single Leg Knee Extension
- Beginner
- Isolation
- Rep-based
- Lower legs
- Upper legs
- Waist
This unilateral isolation exercise targets the quadriceps, specifically the vastus medialis, to improve knee stability and correct muscle imbalances. Using a weight plate provides constant tension throughout the range of motion while seated on a bench.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Sit upright on the edge of a flat bench with your feet hanging freely.
- Place a weight plate on the lower shin of your working leg, just above the ankle.
- Grip the sides of the bench to stabilize your upper body and keep your core engaged.
- Position your non-working foot firmly on the floor or a step for support.
How to do it
- Exhale as you extend your knee, lifting the plate until your leg is parallel to the floor.
- Squeeze your quadriceps at the peak of the movement for a one-second pause.
- Inhale as you lower the weight back to the starting position using a controlled 3-second tempo.
- Perform all repetitions on one leg before switching to the other.
Form checklist
- Keep your torso stationary and avoid leaning back as you lift.
- Ensure the movement is driven solely by the knee joint without hip involvement.
- Maintain a slow, controlled speed to prevent the plate from sliding.
- Keep your toes pointed slightly upward to engage the entire quad.
Pro tips
- Focus on the mind-muscle connection by visualizing the quadriceps shortening as you lift.
- To maximize VMO (inner quad) activation, slightly rotate your foot outward at the top of the extension.
Make it harder
- Incorporate a 2-second isometric hold at the top of every repetition.
- Slow the eccentric (lowering) phase to 4-5 seconds to increase time under tension.
Frequently asked
- What muscles does the weighted seated single leg knee extension work?
- The weighted seated single leg knee extension primarily targets the quadriceps, and also works the abs and hip flexors as secondary muscles.
- What equipment do you need for the weighted seated single leg knee extension?
- The weighted seated single leg knee extension uses weight plate.
- Is the weighted seated single leg knee extension good for beginners?
- Yes. The weighted seated single leg knee extension is a beginner-friendly movement and a strong foundation to build on.