Effect of different exercise trainings on β-cell function, insulin resistance, and osteocalcin levels in overweight men

Many findings have shown the potential relation between osteocalcin (OCN) and regulating energy metabolism. In addition, it has been revealed that physical activity increases OCN levels. Therefore, the present study aimed to investigate the effects of different exercise trainings on β-cell function, insulin resistance, and OCN levels in overweight men.

In this study, 33 overweight, young men [Body mass index (BMI): 29.32±0.75 and age range of 31.50 ± 2.23] were randomly divided into control (n = 11), aerobic exercise (n = 11), and resistance exercise (n = 11) groups. Participants of the exercise group were on the 8-week supervised exercise training program for three sessions per week. Weight, body fat percentage, and BMI were analyzed, and then OCN, insulin, and the homeostasis model assessment of insulin resistance (HOMA-IR) were assessed from fasting blood samples before and after the 8-week exercise program. Finally, data were analyzed by t test and analysis of covariance (ANCOVA).

Based on the results, BMI and body weight, insulin, glucose, and HOMA-IR reduced following the exercise (P < 0.05) whereas serum OCN significantly increased in aerobic exercise (P = 0.001) and resistance exercise (P = 0.000) groups. There were no significant changes in β-cell function in aerobic exercise (P = 0.512) and resistance exercise (P = 0.16) groups. Pearson correlation analysis demonstrated that OCN levels were not correlated with HOMA-IR (P = 0.743) and insulin levels (P = 0.143). However, OCN was positively associated with the homeostasis model assessment of b-cell function (P = 0.014) and glucose (P = 0.025).

The results of the present study confirmed that aerobic and resistance exercises cause some changes in body weight and BMI, as well as the OCN and HOMA-IR. Nonetheless, changes in OCN levels were not predictors of changes in insulin secretion from pancreatic beta cells.