Serum Osteocalcin Concentration in Treadmill-Trained Adult Male Wistar Rats

Mechanical stress is considered to be essential for the regulation of bone mass. The purpose of this study was to determine whether treadmill exer-cise at moderate intensity induces alterations in blood osteocalcin con-centration in rats. Male Wistar rats, aged 5 months, were divided ran-domly into two groups: trained animals (n = 6) and controls (n = 7). Trained rats were exercised 5 days/week for 4 weeks on a motor-driven treadmill. Each exercise session lasted 60 minutes and the average loco-motion speed was 16.2 m/min. After completion of the training period, a blood sample was taken for osteocalcin measurement and the hindlimbs medial gastrocnemius muscles were excised and weighed. Comparative analysis showed significantly lower circulating osteocalcin levels in the exercised rats in comparison to control animals. It is possible that the observed decreased blood osteocalcin concentration is transient in na-ture. Factors including stress may also influenced the results. Serum osteocalcin concentration in treadmill-trained rats