It seems that it is a fracture, but not really a fracture. I see references to stress fractures in your column now and then, and it is not clear what is meant. J.N. Stress fractures are breaks in a bone surface. If not allowed to heal, a stress fracture can develop into a thorough break across a bone.
Stress fractures have their origin in misuse or overuse of the bone.
Improper running mechanics can contribute. In some ways, a stress fracture is comparable to what occurs when you bend any pliable object. For example, if you bend and rebend a piece of metal often enough, eventually the repetitive force forms a surface fracture and ultimately a complete break. A stress fracture calls for rest of the stressed limb and an evaluation of the particular activity or exercise involved. Depending on a stress fracture's severity, it requires from four to 12 weeks of rest.