# Weighted Seated Single Leg Knee Extension - Canonical: https://fitwill.app/exercise/10539/weighted-seated-single-leg-knee-extension/ - Media ID: 10539 - Primary muscle: Quads - Body part: Legs - Equipment: Weighted - Video: https://fitwill.app/videos/10539/weighted-seated-single-leg-knee-extension.mp4 ## Description Weighted Seated Single Leg Knee Extension is a simple but very targeted quadriceps exercise performed on the floor with nothing more than a weight plate and a low block or step. You sit with your torso angled back and supported on your hands, one leg out in front with the heel resting on a low platform, and a weight plate placed on the thigh just above the working knee. From there, you straighten the knee against the resistance of the plate, lifting the heel slightly off the block before lowering it back down under control. This movement isolates one leg at a time, which makes it easy to spot and fix differences in strength between your left and right quadriceps. Because the knee starts nearly straight and moves through a short arc, the emphasis sits right at the end range of extension, where the quadriceps, particularly the vastii and the rectus femoris running down the front of the thigh, have to work hard to fully lock the knee out. That end-range control is something many lifters never train directly, even with heavy squats or leg presses. The setup is what makes the exercise work. The plate has to sit on the thigh just above the kneecap, not on the knee itself, so the load presses the thigh down while the shin is free to rise. The low block under the heel gives the foot somewhere to rest at the start and creates a small, visible range of motion as the heel lifts when the knee reaches full extension. Leaning back on your hands lets you keep your back comfortable and your hips relaxed so nothing else steals work from the quads. This exercise suits people training at home with limited equipment, lifters who want extra quad volume without loading the spine, and anyone working on knee extension strength and control after the knee has been cleared for training. It is also a useful teaching tool: the short range makes it easy to feel the quad contract and learn what a fully straight, locked-out knee is supposed to feel like. Keep the repetitions slow and deliberate rather than fast. The range is short, so momentum offers nothing; the value comes from pressing the back of the knee down hard, holding the top briefly, and lowering with control. Start with a light plate until you can keep the thigh still and the movement coming purely from the knee, then add weight gradually. ## Instructions 1. Sit on the floor and extend one leg straight in front of you, then place your other foot flat on the floor with the knee bent for balance. 2. Rest the heel of your working leg on a low block or step so the foot is slightly elevated and the leg is close to straight. 3. Lean your torso back and place your hands on the floor behind your hips, fingers pointing forward, to support your upper body. 4. Lay a weight plate flat on the thigh of the working leg, a few centimeters above the kneecap, and hold it steady with one hand until you are set. 5. Brace your trunk lightly and keep the thigh relaxed and still; the only joint that should move is the knee. 6. Press the back of your knee down toward the floor to straighten the leg fully, letting the heel rise slightly off the block as the quadriceps contract. 7. Hold the fully extended position for a second, squeezing the quad hard with the plate pressing down on the thigh. 8. Lower the heel back to the block slowly, letting the knee soften only a small amount before the next rep. 9. Breathe out as you extend the knee and in as you lower the heel, keeping the breath steady throughout the set. 10. Complete all repetitions on one leg, remove the plate, then set up on the other side and match the rep count. ## Tips & Tricks - The most common error is placing the plate directly over the kneecap, which is uncomfortable and changes the leverage; keep it on the meat of the thigh above the knee. - If the plate slides during the set, put a small towel between the plate and your skin or hold it lightly with your free hand rather than clamping the thigh. - Watch the heel: if it never leaves the block, the knee is not reaching full extension, so either reduce the weight or focus harder on pressing the knee down. - Do not let the hips rock backward as you press; if your torso keeps sinking toward the floor, brace the trunk more and lean a little more weight into your hands. - Keep the kneecap and toes pointing straight up. Letting the leg rotate outward shifts work away from the quad and can pinch the inside of the knee. - Avoid bouncing the heel off the block. Because the range is so short, fast reps turn it into a reflex drill instead of quad work. - If the floor is hard on your heel or the block is too tall, swap it for a thin mat or a slightly lower step so the knee starts only slightly bent. - Warm the knee up with a few bodyweight versions before adding the plate, especially in cold rooms or early morning sessions. - Expect the non-dominant leg to feel weaker; never let the stronger leg dictate the rep count for both sides. ## Frequently Asked Questions ### What muscles does the Weighted Seated Single Leg Knee Extension work? It targets the quadriceps on the front of the thigh, with strong emphasis on the last few degrees of knee extension where the vastii and rectus femoris do most of the work. The hip and trunk muscles only stabilize; they do not drive the movement. ### Why is the heel placed on a block during the Weighted Seated Single Leg Knee Extension? The block supports the heel at the start and gives it room to lift as the knee straightens fully. It also confirms the leg starts in a near-straight position, so the exercise stays in that short, end-range arc. ### Can beginners do the Weighted Seated Single Leg Knee Extension? Yes, and it is actually a good beginner exercise because the range is short and easy to control. Start with no weight or a very light plate and learn to feel the quad contracting before adding load. ### How heavy should the plate be on the thigh? Use a weight you can press through a full, visible heel lift for 10 to 15 slow reps without the thigh or hips shifting. If the heel barely moves or the plate slides around, it is too heavy. ### Is the Weighted Seated Single Leg Knee Extension a substitute for a leg extension machine? It is not a full substitute because the range is much shorter, but it complements machine work by strengthening the lockout portion one leg at a time. It is a solid option when you have no machine available. ### Should my knee hurt when doing the Weighted Seated Single Leg Knee Extension? You should feel muscular effort in the thigh, not joint pain. If the knee itself complains, reduce the weight, check that the plate sits on the thigh rather than over the kneecap, and stop if discomfort persists. ### Why train one leg at a time instead of both knees together? The single-leg setup lets you match reps side to side and exposes any strength difference between legs. It also lets the plate sit securely on one thigh instead of balancing across two. ### How many sets and reps should I do? Two to four sets of 10 to 15 controlled reps per leg works well for most people. Because the range is short, prioritize a firm squeeze at the top over adding more weight. ### What should I do if the plate keeps slipping off my thigh? Place a towel on the thigh under the plate or wear longer training pants to add friction. You can also hold the plate lightly with your free hand while the other hand supports you on the floor.