Endocrine Abstracts

Introduction: The training year of elite athletes is characterized by different kind and intensities of workload implying different level of metabolic responses of the skeletal tissue, assessable by measuring serum levels biochemical markers.

Methods: Fourteen top-level female skiers, from the Italian Women’s Alpine Ski Team (slalom and giant slalom), were tested at the end of the relative rest period (T1), the pre-competitive season (T2) and the competitive season (T3). Anthropometric and clinical data (age, height, weight, BMI, body fat%, VO_2max (l_O2/min), counter-movement jump (h)) were recorded at each timepoint. Serum levels of bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase (TRAP5b) activities and of osteocalcin (OC) and the carboxyterminal crosslinked telopeptide of type I collagen (b-CTx), were assayed together with the determination of 25(OH)D levels.

Results: No significant variation were found in anthropometric and clinical data over the training year. Formation markers, BAP activity (P<0.01) and OC (P<0.05) and the resorption marker TRAP5b activity (P<0.05) significantly increased from T2 to T3, while beta-CTx showed no significant decreases all over the study. The trends of all bone markers correlated one to each other at T2 versus T3. 25(OH)D levels increased from T1 to T2 and from T1 to T3 (P<0.01) but its variations do not correlate with any of bone markers.

Discussion: The passage through T2 to T3 stimulated the whole bone metabolism, as consequence of the heavy mechanical stimulation during the highly demanding competitive period. These variations were completely independent from the corresponding changes of 25(OH)D. All athletes showed an insufficiency of vitamin D even though they exercised outdoor, mainly at latitudes in which sunlight exposure is adequate.