I know that the squat is supposed to be the king of lower body exercises, but I injured my knee playing high school football and ever since feel a pop in my left knee whenever I reach parallel. Should I continue to squat, only not go so low, or should I totally give them up for a different exercise?
The interesting thing about squats is that while they are indeed one of the very best exercises you can do for your entire body, many people find them difficult, if not impossible, to perform. Because squats place stress on so many areas of the body – from the back to the hips to the knees and even the feet – they can exacerbate chronic orthopedic conditions.
My advice to you is to forgo squats entirely. Just because your knee doesn’t “pop” unless you go below parallel doesn’t mean that that condition can’t evolve into something more serious. It’s not necessarily the depth that’s the issue but the exact motion your body follows as you squat.
I’m sure you’ve tried the leg press before and while they may not quite compare to the almighty squat, it is a reasonable facsimile. Another exercise you can try is the Smith machine squat. Because the bar of the Smith machine works in a fixed range of motion you have the opportunity to adjust your foot position, possibly to a point where your knees are protected. The hack squat is another exercise that offers a degree of control not available in the standard squat.
Normally I wouldn’t be so cautious as I am with my advice to you, but I have known many a strong man succumb to the vicissitudes of the squat and so, unless you are 100% comfortable with it. I would advise finding alternatives.