THE EFFECTS OF 8 WEEKS OF WALKING EXERCISES OF DIFFERENT INTENSITY ON sRANKL AND OSTEOPROTEGERIN LEVELS IN PRE-MENOPAUSAL WOMEN

Abstract

This study aimed to clarify the possible positive effects of an eight week walking program of two different intensities on serum osteo-protegerin (OPG) and soluble receptor-activator of nuclear factor κβ ligand (sRANKL), referred as osteoporosis risk factors. Forty-four pre-menopausal women aged between 30-55 years enrolled in the study and were divided into brisk (BWG; n=15) and moderate tempo walking groups (MTWG; n=16), and controls (CG; n=13). BWG and MTWG walked five days per week starting with 30min per day, steadily increasing up to 51min, at 74% and 54% of their maximum heart rate reserve (HRRmax), respectively. Body weight, body fat ratio, body mass index (BMI), estimated maximal oxygen consumption (VO2max), serum OPG, sRANKL, and sRANKL/OPG ratio were measured before and following the program. Walking programs produced significant increases in VO2max favoring BWG; reductions in body weights, BMI, and body fat ratio in both exercise groups. Significant reductions in serum OPG levels of BWG (p<0.05) and MTWG (p<0.01) were also detected. There were no significant changes in the sRANKL levels and sRANKL/OPG ratios in any group. Significant improvements for protective effects against osteoporosis due to the reduction in serum OPG levels may be attained with either brisk or moderate tempo walking programs. However, brisk walking produces more dramatic effects on cardiorespiratory fitness.