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

Abstract

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 (BMD) in postmenopausal women. We recruited 29 postmenopausal women (age: 62.67 ± 3.9 yr) without regular exercise habits to participate in a 24-wk program of alternating aerobic and resistance training exercise. Blood samples, body composition, and BMD were measured before and after exercise intervention. 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 dual-energy X-ray absorptiometry ( 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 appendicular skeletal muscle mass/height 2 ( r = 0.309, P = 0.031) improvements. 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.