Purpose: The aim of this investigation was to determine if bone mineral density (BMD), bone turnover and bone composition of competitive female cyclists is affected by exogenous ovarian hormone intake. Methods: Fifteen healthy, premenopausal competitive female cyclists (Age = 26 ± 3 yrs), 7 eumenorrhic (EU) and 8 taking exogenous ovarian hormones (EH), completed dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) scans to assess body composition, bone mineral density, bone strength and fracture risk. Blood samples for the analysis of serum bone-specific alkaline phosphatase (BAP) and carboxyterminal crosslinked telopeptide of type I collagen (CTX), carboxy-terminal propeptide of type I collagen (C1CP), leptin and triiodothyronine (T3) were also completed.
Results: Groups were well matched as there were no statistical differences between the groups in maximal oxygen consumption, body composition, total volume of training and years of competitive cycling. No significant differences were seen in leptin or any of the bone markers; BAP, CICP, or CTX. EH did have higher serum T3 levels. While there was no statistical difference in total body and femoral neck BMD Z-scores, lumbar spine BMD Z-scores were significantly (p=0.006) lower in cyclists in the EH group compared the EU group (-0.85 ± 0.5 and -0.01 ± 0.5 for EH and EU respectively). Four of the 8 cyclists in the EH group had lumbar spine Z-scores in the osteopenic range (less than -1.0) and all had Z-scores less than 0. None of the EU group had Z-scores in the osteopenic range. No statistical differences were found in the pQCT results. There was a trend (p = 0.06) toward lower cortical thickness in the athletes using exogenous hormones.
Conclusion: Our results demonstrate that despite normal total body BMD, competitive cyclists taking exogenous ovarian hormones had significantly lower lumbar spine Z-scores than those not taking exogenous hormones; half of whom had lumbar spine Z-scores in the osteopenic range. The low impact nature of cycling was not associated with lower BMD as all the BMD values were within the normal range in the eumenorrheic cyclists.
|Advisor:||Casazza, Gretchen A.|
|Commitee:||Casazza, Gretchen A., Van Loan, Marta D., Waite, Brandee|
|School:||University of California, Davis|
|Department:||Molecular, Cellular and Integrative Physiology|
|School Location:||United States -- California|
|Source:||MAI 51/03M(E), Masters Abstracts International|
|Keywords:||Bone-specific alkaline phosphatase (BAP), Carboxyterminal cross-linked telopeptide of type I collagen (CTX), Dual energy x-ray absorptiometry (DXA), Peripheral quantitative computed tomography (PQCT)|
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