Oral Contraceptives and Bone Health in Female Runners

Abstract

Abstract : Highly trained female athletes may experience loss of menses because of their participation in intense physical activity. Previous cross-sectional research has shown that women with exercise-induced menstrual irregularities have a significantly higher frequency of stress fractures and low bone mass than normally menstruating controls. Longitudinal studies suggest that these women are losing bone mass over time. Low serum estrogen levels are believed to be a principal cause of the bone loss. If so, reestablishing normal estrogen levels in these women should prevent or retard bone loss and decrease the incidence of stress fracture. This was a 2-year randomized trial of the effects of oral contraceptives on bone mass and stress fracture incidence among 150 female competitive distance runners ages 18-26 years. Coordinating Center was at Stanford University and bone mass was measured at five sites: Massachusetts General Hospital, University of California Los Angeles, University of Michigan, Stanford University/Palo Alto VA Medical Center, and Helen Hayes Hospital in West Haverstraw, New York. In addition to a publication from baseline data, two manuscripts from this study have been accepted for publication. One manuscript, The Effect of Oral Contraceptives on Bone Mass and Stress Fractures in Female Runners, concludes that oral contraceptives may reduce the risk for stress fracture, but these data are inconclusive. second manuscript, Risk Factors for Stress Fracture among Young Female Cross-Country Runners, found that a history of stress fractures, lower bone mass, lower dietary calcium intake, younger chronological age, younger age at menarche, and possibly a history of irregular menstrual periods were associated with an increased risk. Another manuscript, The Effect of Oral Contraceptives on Body Weight and Body Composition in Young Female Runners, will be submitted for publication shortly. Two other manuscripts are in preparation.