Do former collegiate gymnasts maintain higher bone mineral density after a 34-year retirement from the sport?

Abstract

The purpose of this study was to determine if the higher areal BMD (aBMD) our group previously observed in former female collegiate artistic gymnasts (GYM; n=17) compared with controls (CON; n=10), is maintained in this cohort now entering menopause (mean age 56 years). This study assessed 20-year changes in fat mass (FM), percent fat (%FAT), fat-free soft tissue, and aBMD of the total body and regional skeletal sites using dual-energy X-ray absorptiometry, as well as cross-sectional differences in trabecular and cortical volumetric bone mineral density (vBMD) and geometry at the radius and tibia using peripheral quantitative computed tomography (pQCT). Independent samples t-tests were used to determine differences between groups at baseline and at 9- and 20-year follow-ups. Repeated-measures mixed model analyses were performed to determine differences in body composition and aBMD within groups over time and to quantify the magnitude of the effects of these variables. At the 20-year follow-up, GYM vs. CON had significantly lower FM and %FAT and higher total body aBMD (all P<0.05). Over 20 years, there were group and time effects at all measured skeletal sites (P<0.05), but no group x time interactions. At the 20-year follow-up, GYM vs. CON had greater total cross-sectional area (CSA), total vBMD, bone strength index (BSI), cortical bone mineral content (BMC), cortical CSA, and strength-strain index (SSI) at the radius, and greater BSI, total CSA, cortical BMC, cortical CSA, cortical thickness and SSI at the tibia (all P<0.05). These data show significant aBMD group effects at all measured sites over 20 years between GYM and CON; however, these differences were not as pronounced as they were at baseline and the 9-year follow-up. The pQCT data are in agreement with the aBMD data, and show that bone geometry differences exist between former gymnasts and controls, decades after retirement from the sport.