Alternating Aerobics with Resistance Exercise Improves Bone Density and Circulating Irisin Levels in Postmenopausal Women

ABSTRACT Purpose Irisin plays an important role in bone-muscle crosstalk. The aim of this study was to elucidate the association of long-term exercise induced irisin response with body composition and bone mineral density in postmenopausal women. Methods We recruited 29 postmenopausal women (age: 62.67 ± 3.9 years) without regular exercise habits to participate in a 24-week program of alternating aerobic and resistance training exercise. Blood samples, body composition and bone mineral density were measured before and after exercise intervention. Results Upper and lower limb bone density (P = 0.004, P = 0.039), calf circumference (P = 0.001), circulating levels of irisin (P = 0.003) and osteocalcin (P < 0.001) increased by exercise. Whereas, waist circumference (P = 0.000), blood osteoprotegerin (OPG) (P = 0.041), receptor activator of NF-κB ligand (RANKL) (P < 0.001), RANKL/OPG ratio (P < 0.001) and estradiol levels (P = 0.003) decreased by training, respectively. According to the observed changes in the measured variables, the irisin circulating levels were significantly and separately related to upper limb BMD (r = 0.462, P = 0.006), lower limb BMD (r = 0.566, P = 0.001), total BMD (r = 0.490, P = 0.008) and T score of DAX (r = 0.489, P = 0.010). The increase in serum irisin levels was found to be positively and separately related to upper limb BMD (r = 0.414, P = 0.026), total BMD (r = 0.453, P = 0.014), calf circumference (r = 0.400, P = 0.031), and ASM/height 2 (r = 0.309, P = 0.031) improvements. Conclusions Long-term alternating exercise training improves bone density, body composition and circulating irisin levels in postmenopausal women, and irisin would mediate bone-muscle crosstalk to exert positive effect of exercise on bone health in postmenopausal women.