Objectives: Engagement in high volumes of physical activity coupled with energy restriction during periods of musculoskeletal development may compromise bone health. Jockeys limit caloric intakes on a weekly basis often from their mid-to-late teens. The aim of this study was to establish whether calcium and vitamin D supplementation would improve bone turnover markers (BTM) and non-weight bearing bone properties of young male jockeys.
Design: A six-month randomised, double-blinded, placebo-controlled trial with two groups of apprentice male jockeys was conducted.
Methods: Participants (age 20.18±3.23years) were supplemented with 800mg of calcium and 400IU of vitamin D (n=8) or a placebo (n=9) daily. Bone properties were assessed at the ultra-distal (4%) and proximal (66%) radius using pQCT at baseline and six months. Vitamin D, P1NP and CTX were assessed.
Results: ANCOVA results for blood-borne markers indicated higher vitamin D levels (18.1%, p=0.014, partial η2=0.38) and lower CTX (ng·L-1) (-24.8%, p=0.011, partial η2=0.40) in the supplemented group with no differences observed in P1NP. Analysis of bone variables indicated no between group differences in either trabecular or cortical bone properties at the 4% and 66% sites post-intervention.
Conclusions: This trial is the first to examine the efficacy of calcium and vitamin D supplementation in improving non-weight bearing bone properties in a young male athletic population. Results indicate positive alterations to bone metabolism; however, longer duration or higher dosage appears to be required to detect changes in bone material properties at the radius. Further examination of such interventions in weight-restricted athletes is warranted.
Keywords: Bone turnover markers; Peripheral quantitative computed tomography (pQCT); Radius; Weight-restricted.
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