Bone mineral density and prevalence of osteopenis and osteoporosis in female elite athletes and controls

Introduction

Lack of physical activity is a risk factor for osteoporotic fractures [1] and in recent years, the use of exercise in maintaining bone health throughout the life span and ultimately preventing osteoporosis-related fractures has been brought into focus [1]. On the contrary, it has been hypothesized that some athletes may be at increased risk for osteopenia or osteoporosis (OP) [2], but the prevalence of OP in young female athletes and controls is not known. Therefore, the aims of this study were firstly to investigate bone mineral density (BMD) in athletes versus controls, and secondly to investigate the prevalence of OP in the same sample.

Methods

This is a two-phase study including part I: questionnaire study, and part II: measurement of BMD with dual-energy X-ray absorptiometry (Prodigy, Lunar). The total population of female elite athletes representing the national teams at junior or senior level, aged 13-39 years (n=938) and a same-age random sample of non athletic controls (n=900) were invited to participate. The questionnaire was completed by 88% of the athletes and 70% of the controls. Based on data from part I, a random sample of athletes (n=300) and controls (n=300), stratified based on age-groups and "risk-profile" for the female athlete triad, was invited to participate in part II of the study. One-hundred-and eighty-six athletes (62%) and 145 controls (48%) participated in both part I and II of the study. For the BMD results, only data from the adult subjects (≥ 20 years) are included (n=103 athletes and n= 120 controls).

Results

Mean total body BMD was higher in athletes (1.24 ± 0.08 g/cm2) than in controls (1.18 ± 0.08 g/cm2) (p<0.001). The prevalence of OP was significantly higher in controls than in athletes in all measurement sites (p<0.01) except for the lumbar spine (p=0.07). A total of 37 controls (30.8%) and 11 athletes (10.7%) were diagnosed with OP in one of five measurement sites (total body, femoral neck, trochanter, femur total or lumbar spine) (p<0.001).
Discussion/Conclusion
In accordance with other studies [3] we found a higher BMD in athletes compared to controls. Furthermore, more controls than athletes were diagnosed with OP which might indicate that athletic training may prevent loss of bone mass and the development of osteoporosis in females.

References

[1]. American College of Sports Medicine. (1995).Med. Sci. Sports Exerc. 27: i-vii.
[2]. Otis C.L. et al. (1997). Med. Sci. Sports Exerc. 29:i-ix.
[3]. Suominen H. (1993). Sports Med. 16: 316-330.