A study has been published in the Archives of Pediatrics & Adolescent Medicine linking certain sports and increased risk of stress fractures in young girls. As April 2011 is National Youth Sports Safety Month, this article will discuss stress fractures and the results and implications of this study.
Stress fractures are a type of fracture in which small cracks appear in a bone without the bone actually breaking. They are most common in the legs and feet, because the bones of the lower extremities bear weight. There are cells in your bones that break down bone tissue, and other cells that build the bone tissue back up. In a healthy adult, there is a balance between bone mineral resorption and bone mineral replacement. In patients with osteopenia or osteoporosis, there is less replacement of bone minerals and more resorption. People with osteoporosis are at an increased risk for developing stress fractures without the physical activity that is normally necessary to develop stress fractures.
In healthy individuals, stress fractures are caused by force that is repeatedly applied to the bones in the legs and feet. Examples of activities that can cause this kind of force are running and activities such as gymnastics and basketball. Too much exercise involving repetitive force to the leg and feet bones actually increases bone resorption. If a person exercises and does not have adequate recovery time, they may have more bone resorption than bone replacement. This leads to weaker bones that are more prone to cracking, or stress fractures.
Stress fractures can be diagnosed using x-rays, bone scans and MRI scans; however, x-rays and bone scans may not show stress fractures until the injuries are a few weeks old. To allow stress fractures to heal, a patient may need to use crutches or a brace to take the weight off of the injured bone. Athletes with stress fractures should not play sports until the injury heals, and when returning to the physical activity, they should resume exercise gradually so they do not re-injure the bone. If the stress fracture is causing someone pain, doctors recommend taking acetominophen. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) may interfere with healing of the injury.
The study of bone fractures in young girls in the Archives of Pediatrics & Adolescent Medicine found that girls ages 9 to 15 who had more than eight hours of certain sports had nearly twice the risk of developing stress fractures than other girls in their age group that did not have this much high-impact activity. Sports that qualified as “high-impact” in this study included track and field, gymnastics, cheerleading and basketball. The risk of developing stress fractures when playing these sports increased with every hour spent practicing or playing the sport. Other sports and activities that were studied did not appear to increase the risk of stress fractures.
Girls with lower bone density and family history of osteoporosis were at greater risk for developing stress fractures during physical activity than girls with normal bone density and no family history of osteoporosis. Girls who had a later menarche, or first menstruation, were more likely to develop stress fractures. Weight did not affect the risk of developing a stress fracture, and neither did the presence of an eating disorder.
One approach to dealing with this increased risk of stress fractures in girls is to modify the training regimens that the girls have to go through. A good approach to practice would involve exercises that will still keep the girls in shape and prepared for their competitive sport, but would be less high-impact and cause less cumulative stress on bones.