title: The effect of calcium and vitamin D supplementation on bone health of male Jockeys.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
authors: School of Exercise Science, Australian Catholic University, Australia. Electronic address: leslie.silk@acu.edu.au.
authors: Leslie N
authors: LN
authors: Silk
authors: School of Exercise Science, Australian Catholic University, Australia.
authors: David A
authors: DA
authors: Greene
authors: School of Exercise Science, Australian Catholic University, Australia; The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, The University of Sydney, Australia.
authors: Michael K
authors: MK
authors: Baker
authors: School of Exercise Science, Australian Catholic University, Australia.
authors: Caron B
authors: CB
authors: Jander
mesh_terms: D000293:Adolescent; D000818:Animals; D015415:Biomarkers / Q000097:blood; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D016723:Bone Remodeling / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006736:Horses; D006801:Humans; D008297:Male; D044342:Malnutrition; D013851:Thinness; D014807:Vitamin D / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D050071:Bone Density Conservation Agents; D014807:Vitamin D; D002118:Calcium
keywords: Bone turnover markers; Peripheral quantitative computed tomography (pQCT); Radius; Weight-restricted