I’m going to start one of your programs but have knee patella issues that prevent me from doing leg extensions and I’ve had issues with barbell squats also aggravating my knees. I’ve been working out at home and have been able to do split squats, lunges and goblet squats. I think I can also do lunges and hack squats. Which exercises can I sub for barbell squats and leg extensions? And at what rep ranges for your programs? Thank you!