shoes actually causes more stress by reducing the body's natural shock-absorbing action, thus increasing the frequency of running injuries. During exercise that applies more stress to the bones, it may help to increase daily calcium (2,000 mg) and vitamin D (800 IU) intake, depending on the individual. Treatment For low-risk stress fractures, rest is the best management option. The amount of recovery time varies greatly depending upon the location and severity of the fracture, and the body's healing response. Complete rest and a stirrup leg brace or walking boot are usually used for a period of four to eight weeks, although periods of rest of twelve weeks or more are not uncommon for more-severe stress fractures. After this period, activities may be gradually resumed as long as the activities do not cause pain. While the bone may feel healed and not hurt during daily activity, the process of bone remodeling may take place for many months after the injury feels healed. Incidences of refracturing the bone are still a significant risk. Activities such as running or sports that place additional stress on the bone should only gradually be resumed. Rehabilitation usually includes muscle strength training to help dissipate the forces transmitted to the bones. With severe stress fractures (see "prognosis"), surgery may be needed for proper healing. The procedure may involve pinning the fracture site, and rehabilitation can take up to six months. Prognosis Anterior tibial stress fractures can have a particularly poor prognosis and can require surgery. On radiographic imaging, these stress fractures are referred to as the "dreaded black line." When compared to other stress fractures, anterior tibial fractures are more likely to progress to complete fracture of the tibia and displacement. Superior femoral neck stress fractures, if left untreated, can progress to become complete fractures with avascular necrosis, and should also be managed surgically. Proximal metadiaphyseal fractures of the fifth metatarsal (middle of the outside edge of the foot) are also notorious for poor bone healing. These stress fractures heal slowly with significant risk of refracture. Epidemiology In the United States, the annual incidence of stress fractures in athletes and military recruits ranges from 5% to 30%, depending on the sport and other risk factors. Women and highly active individuals are also at a higher risk. The incidence probably also increases with age due to age-related reductions in bone mass density (BMD). Children may also be at