Runner's knee - patellofemoral pain syndrome - is very common, felt as a pain in the front of the knee. Forces on the patella (kneecap) can be half a person's weight when walking but up to three times their weight during stair climbing and seven times their weight during squating! A review in American Family Physician highlights how common this condition is, causing16-25% of all injuries in runners. However, it commonly affects people who don't run at all, causing stiffness a