One of the most common injuries among runners is a stress fracture, or "runner's knee." This is a small crack in the bone in the lower leg, usually caused by overuse. The good news: It's highly treatable. There are three main types of stress fractures. The least common is the runner's shin splint, which occurs when the patellar tendon pulls on the kneecap and causes pain somewhere below the knee joint. That's easily treated with icing, massage, rest, and anti-inflammatory medication (like ibuprofen). A more serious stress fracture can occur in the mid-foot area. That's called a peroneal stress fracture and can cause severe pain and swelling in both feet — but only if it goes untreated for months. The most common form of running stress fracture is at the tibia (shin bone) area; this one can occur almost anywhere along that bone, including the back near your knee joint. It tends to take longer to heal than shin splints, so it's important to monitor how you feel after running for several weeks. You'll know you have a problem when you start experiencing pain in your quads or when your legs feel unusually heavy after a long run. If you experience these symptoms regularly, do consult a health expert.