GXMMAT Leg Extension Curl Machine + Bumper Plate Sets (230lbs)

Strengthening the quadriceps through leg extensions can increase explosive power, supporting compound movements such as squats and deadlifts. If you notice that your hamstrings and glutes take on more load during compound movements, then you can strengthen the quadriceps to balance muscle activation. It also hepls in activities that require burst strength, such as sprinting or jumping. Additionally, it improves knee stability, helping to reduce and prevent knee pain and injuries, and can serve as a rehabilitation exercise after knee injury or surgery.

No, they are not the same. Leg extension machine mainly target the quadriceps on the front of the thigh, especially the rectus femoris. Quadriceps strength is crucial for jumping ability, explosive power, and landing stability. Doing leg extensions can further improve anterior chain strength and enhance performance in jumping and ball sports. Leg curl machine mainly target the hamstrings (including the biceps femoris, semitendinosus, and semimembranosus) on the back of the thigh. Strong hamstrings can increase posterior chain strength, protect the knee joint, and enhance explosive power and stride length, improving performance in deadlifts, squats, sprints, and weightlifting.

Using leg extension machine to strengthen the quadriceps itself does not harm the knees, but it's important to use an appropriate weight and maintain proper form. Excessive load or incorrect form will increase stress on the knee and patella, which causes pain. To prevent this, you can follow these guidelines:
1. Appropriate weights: start with a lighter load and gradually increase it over time.
2. Smooth movements: avoid sudden or fast motions. Extend your legs slowly and steadily.
3. Slight bend: avoid locking your knees at full extension when they experience the greatest stress. You can keep a slight 5°-10° bend at the end of the movement to reduce joint strain while still fully engaging the quadriceps.
4. Partial reps: If you experience knee discomfort, perform only partial range of motion (extending the knee from 90° only to 45°) to reduce joint stress.

1. Preparation: Adjust the backrest position so that your knees are placed directly in front of the seat base edge. Align your knees with the pivot point of the machine. The crease behind your knees should be close to the edge of the seat pad. And then rest the leg roller just above your ankles.
2. Lifting Phase: Slowly and steadily raise the leg roller upward and keep your upper body still. Make sure your hips stay in contact with the seat base, and your back rests against the backrest. Lean back a little, grip the handles, keep your hips down, and move only your legs throughout the motion.
3. Top Hold: When you reach the top of the movement, pause for one second at the peak and squeeze your quadriceps, but be careful not to hyperextend or lock your knees.
4. Lowering Phase: Slowly lower the leg roller back to the starting position.

Whether you should do more reps or increase the weights depends on your training goals. If you want to build muscle strength, you can increase the weight and lower the reps when doing leg exercises using cable machine. If your goal is to improve muscular endurance, you can lower the weight and increase the reps.

The important thing is to use a progressive training approach to prevent muscle injuries. For beginners, adding a small increment weight (about 5–10%) every 2–3 weeks is recommended. As the weight increases, your rate of adaptation will slow down — intermediate lifters may need to progress every 3–4 weeks, while advanced lifters may need 4–6 weeks before increasing the load.