This article originally appeared on Sonima.com. About 1 in 4 Americans suffers from knee pain, according to a 2011 study published in the Annals of Internal Medicine. Rather than ignore that wincing discomfort until it’s unbearable, see if you can ease the ouch with these three simple strengthening exercises from Sonima’s pain and anatomy advisor, Pete Egoscue. You may be surprised to find that the pain you feel in your knee is due to weakness and instability in other areas of the body. The…