“The posterior tibialis is a muscle that originates on the back, or posterior, part of the tibia and fibula (your lower leg bones), up close to your knee,” explains Cathlin Fitzgerald, D.P.T, C.S.C.S.

Tight calves and shin splints are common issues runners face. But they shouldn’t be the only areas you pay attention to in your lower legs. If you’re ignoring a small stabilizing muscle called the ...