Excessive force on bone causing a hairline crack to appear. Symptoms: A very specific area of pain and tenderness that will normally feel worse on weight bearing but may also hurt when not weight bearing (even at night). The most common sites for a stress fracture in runners are the inside edge of the tibia (shin bone) and the metatarsals (the long toe bones). Common causes: Overtraining � doing too much, too soon. Poor technique or imperfect biomechanics can also be a factor. What to do: Seek medical advice for a diagnosis if you suspect a stress fracture. Do not run, or you risk a full-blown fracture and much longer away from your running.