Bone geometry according to menstrual function in female endurance athletes

Athletes have higher bone mineral density (BMD) relative to nonathletes. In amenorrheic athletes BMD may be compromised by estrogen deficiency, but it is unknown whether this is accompanied by structural differences. We compared femoral neck bone geometry and density of a-/oligomenorrheic athletes (AAs), eumenorrheic athletes (EAs), and eumenorrheic controls (ECs). We recruited 156 women: (68 endurance athletes and 88 controls). Femoral neckBMD, section modulus (Z), and width were measured using dual-energy X-ray absorptiometry. Menstrual function was assessed by questionnaire and classified asEA(≤10 periods/year) orAA(≥9periods/year): 24 athletes were AA and 44 EA. Femoral neck BMD was significantly higher in EA than AA (8 %, difference) and EC (11 % difference): mean [SE] 1.118 [0.015], 1.023 [0.020] and 0.999 [0.014] g cm-2, respectively; p>0.001. Z was significantly higher in EA than EC (11 % difference): EA 667 [19], AA 625 [21], and EC 592 [10] cm3; p>0.001. Femoral neck width did not differ between groups. All differences persisted after adjustment for height, age, and body mass. The higher femoral neck Z andBMDin athletes, despite similarwidth,may indicate that exercise-related bone gains are endosteal rather than periosteal. Athleteswithamenorrhea had smaller increments in bone mass rather than structural adaptation. The maintained femoral neck width in controls may be an adaptive mechanism to conserve bone strength in bending despite inactivity-related bone decrement.© Springer Science+Business Media New York 2013.