I believe too that one has to squat if they can, as it is the most difficult and demanding exercise one can do. If this is so, it also becomes the most potentially productive exercise one can do. I don't believe one can squat "slowly". One can and should squat "rhythmically" with enough body lean and movement to maximize their leverages and maintain what is for them, a safe position and this is what they should do. This is what I do when I squat, especially when I squat heavily. Remember, one DOES NOT EVER SQUAT "UPRIGHT". There must be some body lean (without rounding the back) so that the hips are behind the bar, the upper body and lower body are aligned so that the resistance can be counterbalanced, and most importantly, so that the hips "have some place to go" as they are driven forward as one comes out of the bottom position. If one tries to stay literally upright, the hips cannot be moved forward and one cannot then squat with a weight that will stimulate changes in their body.
- Dr Ken