o.k., whenever I do squats I end messing up my knees. I can leg press 16 plates with no pain. I figured out that the reason this is happening is because I have far too much forward knee flexion on the descent. The center of gravity shifts forward on my way down and my knees travel too far forward. I squat with my knees and not my hips. Is this a balance issue? Flexibility?? How can I fix the problem? I want to perfect my form and hit the squats hard with 5X5.