I recently have been trying a 20-rep squat routine twice a week before my regular workouts. I recently started to develop some pain in my right knee. Could this be due to a strength imbalance? Do I need more posterior chain work? Any advice would be appreciated.
Ace I hate to see a reply go unanswered. But really I doubt this is a question anyone could answer (categorically). Maybe your technique is poor, and on the way up you are rotating ever so slightly. Maybe you are doing far too much. 20reps twice a week, if you are performing RM sets seems like a hell of a lot. How much experience do you have with the squat? If you have performed lower reps with no probs, then stick to that. As the old joke goes, a man walks into the doctors office, raises his arm and says, "Doc, it hurts when I raise my arm like this. What should I do?". The doctor replies "Dont raise your arm like that. Oh and that will be $200."
LOL, I'm not being supercilious with you ace, but really, pain is your bodies way of telling you something is wrong. Now unless you are prepared to pay some bucks to get yourself assessed, eg an ART practitioner, then your only other course of action is to abandon the squats. Then after a period of time slowly re-introduce them. Before that though I would make the suggestion of doing hindu squats, these are bodyweight squats. It is just my belief, but I don't think that most people should be rushing to leap under the squat bar until they can do 500 of these.
They are great for your knees, build up your muscle, and will leave you far more winded than even 20 rep squats.
Do a search with google, from memory, you'll find plenty of info on them on matt furey's site, and also on clarence bass's.
Hope this was of some limited help.