Leg Extension: How to Do It Right

You sit in the leg extension machine with your shins behind a padded roller and straighten your knees against the weight. Nothing else moves, so your quads get all the work and your back stays out of it. Below you will find how to set up the machine, how far to lift, the muscles worked, sets and reps, and the mistakes that make people's knees complain.

The leg extension works the quadriceps, the four muscles on the front of the thigh, and almost nothing else. All four heads straighten the knee, and the rectus femoris in the middle also crosses the hip, so it works a little more when you sit upright. Your core and your hands on the handles only keep the hips on the seat. That is why the leg extension is called an isolation exercise: it is the most direct way to load the quads.

For muscle growth, do 3 to 4 sets of 10 to 15 reps. Pause for a second at the top and lower under control. Rest 60 to 90 seconds between sets. Stop each set with 1 or 2 good reps left and add a plate once you reach 15 clean reps on every set. The leg extension works well with higher reps and even as a finisher with 20 reps. Heavy sets of 5 or 6 are not worth the strain on the knee.

The leg press and the squat train the quads, glutes and inner thighs together and let you move much more weight. The leg extension trains the quads alone, so it is the exercise to add when your quads lag or when you want a pump without loading the back. It also hits the rectus femoris in the middle of the thigh harder than squats do. Most people do best with a squat or leg press first and the leg extension after it. If your knees are sore from squats, use lighter weight and higher reps on the leg extension, and stop and see a professional if the pain stays.

Single leg extensions fix a weaker side and are easier to control. Toes pointed straight up is the normal setting. Pointing them slightly out or in changes very little, so pick the position that feels best for your knees. A pause of 2 seconds at the top makes a light weight much harder. In the app the exercise is called Leg Extension, and single leg sets can be logged with half the weight.

No leg extension machine? A squat, a leg press or a Bulgarian split squat trains the quads with more weight and brings in the glutes. At home, a reverse lunge with dumbbells or a slow bodyweight squat with a pause at the bottom works the same muscles. The moves below are the closest swaps.

The leg extension is the second exercise on Day C of Full Body Foundation, 3 sets of 6 to 10, with the leg press and the Bulgarian split squat as swaps. In Curves & Confidence it closes Day C with 3 sets of 8 to 12 for the quads. Log every set in GymDroid and the plan sets your next weight. On iPhone and Android.

Full Body Foundation · Curves & Confidence · Dumbbell Home Essentials

The quadriceps on the front of the thigh, all four heads. The rectus femoris in the middle gets a bit more work because it also crosses the hip. Nothing else moves, so the glutes and hamstrings get almost no work.

Not for healthy knees when the seat is set right and the weight is lowered under control. Problems come from a wrong seat position, dropping the weight and going too heavy. If a knee hurts during the set, stop and see a professional.

10 to 15 reps for 3 to 4 sets works best for most people. Pause at the top and lower for 2 seconds. Sets of 20 as a finisher work too.

After. Do the squat or the leg press first while you are fresh, then the leg extension for extra quad work. Before squats, a light set of 15 can warm up the knees.

Not the same movement without a machine. A reverse lunge, a Bulgarian split squat or a slow bodyweight squat trains the quads at home. A resistance band around the ankle on a chair is the closest copy.

Straight up is the standard. Turning the toes a little in or out changes very little. Pick the position that feels best for your knees.