Bone loss in adolescent female runners

When most people think of stress fractures and osteoporosis, they think of women going through (or already have gone through) menopause. One of the most commonly affected demographic groups, though, are young female runners. That is by far the most common type of patient I see with a stress fracture – the Charleston high school or college cross country or track runner with a stress fracture in a bone of the foot, ankle, or leg.

It has been shown that an individual develops about half of his or her bone mineral content during his or her adolescent years. In these formative years, factors such as decreased or absent menstrual cycles, lower body mass indices, decreased caloric intake, and participation in endurance running sports can negatively affect bone loss. An important question then becomes whether these young female athletes regain that lost bone.

Female runners are at risk for bone loss

In the June 2011 issue of Medicine & Science In Sports & Exercise, Michelle T. Barrack, Ph. D. et al. present the results of a study attempting to answer that question. They analyzed 40 female runners with an average age of 15.9. They then administered a survey three years later to evaluate menstrual status and sports training and performed DEXA scans to assess bone mineral density.

Their findings were not encouraging. 87% of the female runners with low bone mineral density at the first test still met the criteria for low bone mass three years later. Compared to females with normal bone mass levels, those with decreased bone mass tended to run more total miles and more miles in the offseason. Almost half had menstrual irregularity or took oral contraceptives for menstrual irregularity. What was harder for the authors to determine was whether the bone loss was irreversible or whether those females engaged in activities, such as increased running, or had factors, such as menstrual irregularities, that prevented them from regaining bone mass.

Also read:
The role of bone density in stress fractures
Stress fracture: Frequently asked questions about this injury

I hope female athletes and their parents and coaches read this post. This study emphasizes how important it is to take bone health seriously. High school and college track and cross country runners (and athletes of other running sports) are at risk for bone loss and subsequent stress fractures. I would strongly encourage them to seek medical attention from a sports medicine physician for any lingering bone pain and determine if they have a stress fracture. In addition to stopping the repetitive stress to get the fracture to heal, I would stress that she get a bone density test to evaluate for bone loss and treat it if found.

In addition, young female athletes need to understand the risk factors for bone loss and avoid them or correct them. If a high school or college female athlete is not having regular menstrual cycles, she should discuss that issue with her OB-GYN or family doctor. She should eat enough calories per day to meet not just average daily caloric needs, but the increased nutritional demands of high-level athletes. And she should not try to intentionally restrict her caloric intake. If any such issue exists, she should seek the advice of a sports nutritionist.

This study shows that once bone loss occurs in adolescent runners, it is unlikely to significantly improve. Almost 9 out of 10 young female runners in this study continued to have low bone mass three years later. Since adolescent years are the years for much of the body’s bone development, these low levels are likely to persist throughout life. Young females need to work to develop proper bone mineral content early in life and keep their bones healthy throughout their sports careers.