Leg Extension (Machine)
The Leg Extension Machine is a seated isolation exercise that specifically targets the quadriceps muscles on the front of the thigh. By stabilizing the hips and moving only at the knee joint, it allows for focused strengthening and development of the quads without engaging other muscle groups.
The AI optimizes this isolation exercise by analyzing your set duration and intensity to ensure you are maintaining constant tension rather than relying on momentum. By integrating your recovery data and previous leg training volume, the app adjusts the weight and rep targets in real-time to maximize quadriceps hypertrophy while protecting knee health. If you report joint discomfort, the system remembers this association and can automatically substitute biomechanically friendlier options like the leg press in future workouts.
Form Cues
- Align your knees with the machine's pivot point
- Hold the side handles for stability
- Extend your legs until straight but not locked
- Squeeze your quadriceps hard at the top
- Lower the weight slowly and under control
- Don't let your hips lift off the seat
- Don't kick the weight up using momentum
- Don't lock your knees forcefully at the top
- Don't let the weight stack slam down
- Don't rotate your feet excessively
Common Mistakes
- Misaligned knee pivot point
- Using excessive momentum
- Lifting glutes off the pad
- Shortening the range of motion
- Lowering the weight too fast
Muscles Worked
This exercise is the primary isolation movement for the quadriceps femoris group, targeting the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. It is particularly effective for strengthening the terminal knee extension and placing tension on the rectus femoris in a shortened position.
Primary
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