Bone accrual in oligo-amenorrheic athletes, eumenorrheic athletes and non-athletes.

Abstract

BACKGROUND\nMechanical loading improves bone mineral density (BMD) and strength while decreasing fracture risk. Cross-sectional studies show that exercise advantage is lost in oligo-amenorrheic athletes (OA). Longitudinal studies examining the opposing effects of exercise and hypogonadism on bone are lacking in adolescents/young adults.\n\n\nOBJECTIVE\nEvaluate differences in bone accrual over 12\u202fmonths in OA, eumenorrheic athletes (EA) and non-athletes (NA). We hypothesized that bone accrual would be lower in OA than EA and NA, with differences most pronounced at non-weight bearing trabecular sites.\n\n\nMETHODS\n27 OA, 29 EA, and 22 NA, 14-25\u202fyears old, completed 12-months of the prospective study. Athletes were weight-bearing endurance athletes. Subjects were assessed for areal BMD and bone mineral content (BMC) using DXA at the femoral neck, total hip, lumbar spine and whole body (WB). Failure load (a strength estimate) at the distal radius and tibia was assessed using microfinite element analysis of data obtained via high resolution peripheral quantitative computed tomography (HRpQCT). The primary analysis was a comparison of changes in areal BMD, BMC, and failure load across groups over 12-months at the respective sites.\n\n\nRESULTS\nGroups did not differ for baseline age, height or BMI. Percent body fat was lower in both OA and EA compared to NA. OA attained menarche later than EA and NA. Over the follow-up period, OA gained 1.9\u202f±\u202f2.7\u202fkg of weight compared to 0.5\u202f±\u202f2.4\u202fkg and 0.8\u202f±\u202f2.3\u202fkg in EA and NA respectively (p\u202f=\u202f0.09); 39% of OA resumed menses. Changes in BMD, BMD Z-scores, and tibial failure load over 12-months did not differ among groups. At follow up, EA had higher femoral neck, hip and WB BMD Z-scores than NA, and higher hip BMD Z-scores than OA (p\u202f<\u202f0.05) after adjusting for covariates. At follow-up, radial failure load was lower in OA vs. NA, and tibial failure load lower in OA and NA vs. EA (p\u202f≤\u202f0.04 for all). Change in weight and fat mass were associated with changes in BMD measures at multiple sites.\n\n\nCONCLUSION\nDespite weight gain and menses recovery in many OA during follow-up, residual deficits persist without catch-up raising concerns for suboptimal peak bone mass acquisition.