I find definitely going no more than 90 degree to be better on the knee and this makes sense mechanically as well. The other may strengthen quads better but the more flex in the knee the more aggressive all angles are on everything from the patellar tendon to the menisci. The only way it could possibly be better is that if you do a full squat you cannot do nearly as much weight. I know in my case with my questionable patellar tendon I do much better going down no more than 90 degree bend at the knee.
This has been answered in a million places if you do a search online. Here are some starting points:
Starting Strength (60 page chapter on squatting)
Starting Strength Wiki
Stronglifts squat tutorial
Squat analysis
The Why of Full squats
In short: always squat below parallel - that is, where the crease of the hip joint is below the knee joint. It is a safer and far more effective way to train.
Most exercise physiologists agree that extreme points of flexion and extension are harmful to the knee. However, if you have trained your muscles to be stronger in that full range of motion, much of the force is taken off of your ligaments and tendons. Physiologists can't conclude that a low squat is bad for this exact reason. They see trained individuals who have no knee problems and get very, very low. It all depends on your genetics and the way you train. Most people don't need a squat much lower than perpendicular for their activities. If you do though, the important thing is to take the time, get flexible, keep tension in the muscles throughout the whole range, and don't lift more weight than you can.
I dont exactly do a whole lot of athletic activies, simply looking to pack on more muscle. I've been doing half squats for over a year now and wondering if I should or shouldn't change over.
best stretches for squat flexibility?
best stretches for squat flexibility?