Bone Health of Female Elite Cyclists Is Characterized by Impaired Cortical and Trabecular Microarchitecture

Purpose: Many elite road-race cyclists have low areal bone mineral density (aBMD) as previously shown by dual-energy X-ray absorptiometry (DXA). However, aBMD provides limited insight into bone quality. Therefore, this cross-sectional study aimed to assess volumetric BMD (vBMD), bone microarchitecture, and bone strength in elite road-race cyclists using high-resolution peripheral computed tomography (HR-pQCT), along with aBMD measured by DXA. Methods: Twenty female elite (Tier 3/ 4) road-race cyclists (21±2 y; BMI 20.8±1.6 kg/m²) had DXA scans at the hip, lumbar spine, and total body to assess aBMD, and HR-pQCT scans at the distal radius and tibia to assess vBMD, bone microarchitecture, and failure load. Z-scores were calculated for all outcomes, with Z-scores <-1 considered as low or impaired. The risk of low energy availability was assessed using the Low Energy Availability in Females Questionnaire (LEAF-Q). Results: Low aBMD was observed in 20%, 25%, 35%, and 10% of the participants at the hip, femoral neck, lumbar spine, and total body, respectively. Low total vBMD was present in 45% and 40% at the distal radius and tibia, respectively. With regard to bone microarchitecture, the tibial cortical area and tibial cortical thickness were low in 40% and 60% of the participants, respectively, and number and thickness of trabeculae at the tibia were low in 40% and 30% of the participants. The impairments were less pronounced at the distal radius. Failure load was low in 15% (radius) and 20% (tibia) of the participants. Conclusions: Along with low aBMD, a substantial proportion of female elite cyclists had impaired bone microarchitecture, mainly characterized by a low cortical area and thickness and low trabecular number and thickness, especially at the distal tibia.