Bone metabolism markers and vitamin D in adolescent cyclists.

This study aimed to describe bone metabolic activity in adolescent competitive cyclists compared to age-matched controls. The main result is that younger subjects present a higher bone turnover than the older ones. Moreover, cyclists under the age of 17 have higher scores on all markers than age-matched controls. PURPOSE: The purpose of this study was to describe bone metabolic activity in adolescent competitive cyclists compared to age-matched controls. METHODS: Twenty-two male adolescent cyclists between 14 and 20 years (y) and 20 age-matched controls participated in this study. Serum osteocalcin (OC), aminoterminal propeptide of type I procollagen (PINP), and ß-isomerized C-telopeptides (ß-CTX) were analyzed by electrochemiluminescence immunoassay (ECLIA); plasma 25 hydroxyvitamin D [25(OH)D] was analyzed by enzyme-linked immunosorbent assay (ELISA). RESULTS: Analysis of variance revealed no significant differences in bone metabolism markers and vitamin D between cyclists and controls. Cyclists over 17 y had a significantly lower concentration in bone formation and resorption biochemical markers compared to cyclists under 17 y (all P < 0.05). Moreover, controls over 17 y presented lower concentration for PINP (P < 0.05) compared to their peers under 17 y. Comparisons between cyclists and controls under 17 y revealed higher concentrations of OC and PINP (P < 0.05) in cyclists. Group interaction by age was found for OC, PINP, and ß-CTX (P < 0.01). Cyclists over 17 y had higher concentrations of [25(OH)D] (P < 0.05) than age-matched controls. CONCLUSIONS: The present results support the idea that cycling during adolescence may be associated to a decrease in bone turnover that may affect bone health later in life.