I appreciate your response and perspective. Based on current reserach - in both rehabilitation and exercise science - I have to disagree about the machine. I do not doubt you experience pain when using the machine. There are many contributing factors to the experience of pain and the current reserach does not support this machine being danerous.

This machine is both safe and effective. The research that shows greater levels of stress at the front of the knee compared to squats does not represent harmful levels of stress. The leg extension machine does not contribute to the development of pain or injury.

While I prefer squats, the leg extension machine is appropriate in many cases for quadriceps development.

Our bodies are resilient. There are many myths regarding exercise technique and injury. For example, a rounded low back is safe when lifting, posture does not influence pain, and their is no ideal way to squat.

I am happy to share the research with you if you are interested.

Best,

Zach