A study in the Archives of Pediatrics and Adolescent Medicine scientific journal suggests that adolescent girls involved in high-impact sports and activities, such as running, basketball, gymnastics and cheerleading, face a higher risk of stress fractures, and long-term effects on bone health.

Over a 15 year period, a total of 6831 girls aged 9 to 15 were followed in an ongoing study.  Each hour per week of high-imapct activity increased the risk of stress fractures by 8 percent.

The lead author, Alison Field of Children's Hospital and Harvard Medical School in Boston, suggested that some of the time spent on high-impact activities should be replaced with low-impact exercise, such as cycling.