Author(s): HILKENS, L., VAN DIJK, J.W., Institution: HAN UNIVERSITY OF APPLIED SCIENCES, Country: NETHERLANDS, Abstract-ID: 1565

INTRODUCTION:
Impaired bone health has been consistently reported in elite road cyclists, raising the question of whether reduced bone mineral density (BMD) is a general characteristic of cycling or a discipline-specific phenomenon. Therefore, we assessed BMD in elite cyclists across different cycling disciplines.
METHODS:
In this cross-sectional study, 95 male and female elite and world-class cyclists from different cycling disciplines (road cycling: n=72, 22±4 y; BMX: n=11, 26±4 y; sprint track: n=11, 23±5 y) underwent dual-energy X-ray absorptiometry to assess total and regional BMD and body composition. Between-group differences in body composition were analyzed using ANCOVA with sex as a covariate. Z-scores were calculated for BMD and interpreted based on the American College of Sports Medicine BMD classification (Z-score <-1 indicates low BMD) and used to determine the prevalence of low BMD. Associations between body composition variables and BMD were assessed in the overall sample using partial correlations adjusted for sex. Data are presented as mean±SD.
RESULTS:
After adjustment for sex, both body mass and BMI were lowest in road cyclists (65.1±8.1 kg; 20.7±1.5 kg/m²), followed by BMX (78.1±11.7 kg; 24.3±2.6 kg/m²), and sprint track cyclists (85.1±12.9 kg; 26.4±2.1 kg/m²). All pairwise group comparisons were statistically significant. Lean mass was ~13 kg higher in sprint track cyclists and ~6 kg higher in BMX cyclists compared to road cyclists (both P<0.01), whereas fat percentage did not differ between groups (P=0.11).
Low BMD was observed exclusively in road cyclists, with a prevalence of 48% at the lumbar spine, 36% at the hip, 38% at the femoral neck, and 44% at the total body. Corresponding mean Z-scores in road, BMX, and sprint track cyclists were −1.0±1.1, 1.1±0.9, and 1.5±1.1 at the lumbar spine, −0.6±0.8, 0.7±0.9, and 1.9±0.6 at the hip, −0.7±0.8, 0.9±1.1, and 2.6±1.0 at the femoral neck, and −0.9±1.1, 1.1±0.9, and 2.0±0.7 for the total body.
Across all cyclists, body weight, BMI and lean mass were moderately to strongly associated with BMD at all skeletal sites when adjusted for sex (r = 0.59 to 0.79, P<0.001 for all).
CONCLUSION:
Impaired bone health is highly prevalent in elite road cyclists but absent in BMX and sprint track cyclists, who displayed high to very high BMD. Discipline-specific body mass and lean mass, as well as differences in training-related mechanical loading, likely contribute to these marked differences in BMD.