Effects of Different Intensity Resistance Exercise Programs on Bone Turnover Markers, Osteoprotegerin and Receptor Activator of Nuclear Factor Kappa? Ligand in Post-Menopausal Women

Abstract

Objective: To investigate the effects of 12-week two-different intensity resistance training programs on bone turnover markers, bone mineral density (BMD), osteoprotogerin (OPG), and soluble receptor activator of nuclear factor kappa β ligand (sRANKL) in postmenopausal women. Material and Methods: Forty healthy women (aged 45-60 years) participated in the study. High-intensity group (HIG; n=14) worked 4 days a week and performed two sets of 8-10 repetitions at ~70-80% of 1 repeat maximum (RM). Low-intensity group (LIG; n= 13) worked in the same duration, with 13-17 repetitions, at ~40-50% of 1RM. Control group (CG; n = 13) did not perform any exercises. Body composition, 1RM value for 10 exercises, repetitions of sit-ups for 30 seconds, bone formation and resorption markers, serum osteocalcine (OC), bone alkaline phosphatase (BAP), βCrossLabs, OPG, and sRANKL levels were measured before and after the training program. BMD was measured via dual energy X-ray absorptiometry. Results: Resistance training caused increases in spine BMD in HIG and LIG (p< 0.05), and OC levels increased in the HIG (p< 0.05). We observed a significant difference between the percent change in HIG versus the percent change in CG in the spine BMD values (p< 0.01). sRANKL levels decreased significantly in all three groups. Strength measures increased in both exercise groups (p< 0.001), favoring the HIG. Conclusion: High-intensity resistance training may be more effective for increasing muscle strength and protecting against osteoporosis and fractures. Due to insignificant changes in OPG levels and significant reductions in sRANKL in all groups, measures of circulating OPG and sRANKL levels seem not to be so useful to predict BMD or bone turnover status after resistance training programs. Therefore, these parameters remain to be determined directly in the bone microenvironments together with BMD measures and bone turnover markers.