Osteocalcin and glucose metabolism in postmenopausal women subjected to aerobic training program for 8 weeks

Abstract

Results of animal studies suggest that osteocalcin (OC) plays an important role in the regulation of carbohydrate metabolism. The aim of the present study was to assess the relationship between biochemical indices of bone turnover and carbohydrate metabolism in postmenopausal women subjected to aerobic training for 8 weeks. The study was conducted on 44 postmenopausal women: 27 of them participated in the training program, and 17 did not undertake any additional physical activity during the study period (control group). Subjects performed a cycle-ergometer physical workout at a level of 70% to 80% of ventilatory threshold intensity for 8 weeks (40-minute sessions, 3 times per week). Serum concentrations of OC, C-terminal telopeptide of type I collagen, osteoprotegerin (OPG), insulin, and glucose were measured; and the homeostasis model assessment of insulin resistance index (HOMA-IR) was calculated before and after the 8-week training program. The training program caused significant decrease in levels of OC (P < .05), HOMA-IR (P < .05), and waist-to-hip ratio (P < .05). No significant changes were observed in C-terminal telopeptide of type I collagen, OPG, insulin, and glucose concentrations. Pretraining OC levels inversely correlated with concentrations of OPG (P < .05), glucose (P < .05), and insulin (P < .05) and with HOMA-IR values (P < .05). Our study revealed an association between serum OC concentrations and metabolic markers in postmenopausal women. Regular physical activity was associated with decrease in central adiposity and OC levels and slight reduction of insulin resistance. However, no direct relationships between training-related changes in OC concentrations and metabolic markers were observed.