Well I'm no expert, but I noticed that when you come up, you kinda jerk and lock your knees. In doing this, I wonder if this could cause damage to your knees in the long run. I'd like to know for myself, if a slow coming up all the way is better than doing it how you're doing?
well, you'll get people (coaches/trainers) telling you not to forcefully accelerate through the squat all the way up through lockout, but that's more fitness-industry regurgitation, which helps people who are out of shape not get injured.. but you have to think about how much more vicious locking out of the joints is, in say a running jump etc.. in fit athletes, locking out completely is fine.. most athletes are taught to accelerate the bar with max speed all the way up, regardless of how heavy it is.. this will always cause some kind of full extension at the knee/hip.. it really is not much of a problem, it only becomes a problem in less-fit individuals, sedentary, elderly, etc..
as always though, listen to your body.. if you lock out and you feel it is bothering your knees, cut it out and see how you feel.. locking out has never posed a problem with myself or anyone i've trained, in fact i would say it has helped prevent injury, as it helps develop the VMO more, which stabilizes the patella during all types of movements.. weak vmo is a cause of many many knee injuries.
peace!
