Abstract
PURPOSE: To determine if bone mineral density (BMD) and bone strength of competitive female cyclists is lower than the average population due to the low impact nature of their training. METHODS: Eight competitive female cyclists (Age = 26 + or - 4 yrs) completed a maximal cycle ergometer exercise test and dual X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) scans to assess body composition, bone mineral density, bone strength and fracture risk. Serum samples for bone-specific alkaline phosphatase (BAP), carboxyterminal cross-linked telopeptide of type I collagen (CTX), parathyroid hormone (PTH), serum 25-hydroxy-vitamin D levels and estrogen were also collected. Summary of Results. Characteristics of the group included a VO2max of 53.7 + or - 5.5 ml times kg-1 times min-1, body fat of 20.2 + or - 3.8% and a total volume of training of 10.5 + or - 3.3 hrs per week. Total BMD was 1.2 + or - 0.09, AP Spine was 0.93 + or - 0.12 and Femur was 0.89 + or - 0.08 g/cm2. Average z scores for total BMD was 0.1 + or - 1.1, AP Spine was -1.1 + or - 1.1 and Femur was -0.19 + or - 0.06. CONCLUSION: Our results demonstrate that despite normal total body BMD, competitive cyclists had AP spine Z scores in the osteopenic range. This is especially significant in that athletes usually have higher than average BMD. Recommendations to add weight bearing cross training into the training regimens of cyclists may be warranted.