The effect of regular fitness training, sex hormones, and turnover of selected bone markers on sclerostin levels in young women

INTRODUCTION: Regular physical activity (PA) is a recognized factor stimulating bone formation. In recent years, osteocytes have been shown to be involved in the metabolism of bone tissue in addition to osteoblasts and osteoclasts. The aim of the study was to analyze the effects of regular fitness training, sex hormones, and selected bone turnover markers on sclerostin levels in young women. MATERIAL AND METHODS: The cross-sectional study involved 78 women including 39 who regularly engaged in fitness training (for 1 h three times a week for 3 months) and 39 leading a sedentary lifestyle. Anthropometric measurements and glucose, lipids, insulin, estradiol, testosterone, free testosterone, androstenedione, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate, intact parathyroid hormone (iPTH), vitamin D, osteocalcin, β isomer of C-terminal telopeptide of type I collagen (β-CTx) and sclerostin levels were measured. RESULTS: Activity of women (study group) who were on a high level of PA ranged between 2262 and 6606 MET/min/week (mean, 3843.16; SD = 1230). All of the control group were on low level of PA (198-1617 MET/min/week; mean, 841.06; SD = 302.01). Significantly higher levels of iPTH and β-CTx were observed in the study than in the control group (p < 0.01). We did not observe differences in vitamin D (p > 0.12), osteocalcin (p > 0.23), or sclerostin levels (p > 0.37) between groups. There were significant negative correlations between log10 sclerostin and log10 DHEA levels (r = –0.24; p < 0.05). A multivariate stepwise backward linear regression model for sclerostin as an independent variable, with the explanatory variables physical activity, estradiol, testosterone, and DHEA levels, did not reveal any effect on changes of sclerostin levels. The model with the explanatory variables vitamin D, iPTH, β-CTx, and osteocalcin also did not show effects on changes of sclerostin levels. CONCLUSIONS: Our results show that regular fitness training, sex hormones, vitamin D, iPTH, β-CTx, and osteocalcin did not influence circulating sclerostin levels in young women.