Effects Of Aerobic Combined Resistance Exercise On BMD And Serum Irisin In Postmenopausal Women

Objective:To investigate the effects of aerobic combined with resistance exercise on bone density and serum irisin levels in postmenopausal women,and provide theoretical and experimental data for exercise-based prevention and treatment of postmenopausal osteoporosis.Methods:29 postmenopausal women（aged 52-70 years）were divided into a control group（CG,n=14）and an exercise group（EG,n=15）.The EG participated in a 24-week program of aerobic and resistance exercise:aerobic exercise consisted of group fitness classes lasting approximately 60 minutes,twice a week,for a total of 48 sessions,with exercise intensity maintained at 55-65%of HR_max;resistance exercise consisted of elastic band training for the first 12 weeks and adjustable weight equipment training for the next 12 weeks,lasting approximately 60 minutes per session,twice a week,for a total of 48 sessions,with intensity set at 50-85%of 1RM.Aerobic and resistance exercise were alternated every other day.The CG did not participate in any exercise,and all subjects were instructed to maintain their usual lifestyle and dietary habits.Before and after 24 weeks,the subjects’ height,weight,BMI,waist circumference,calf circumference,total body bone density（including head,upper limbs,lower limbs,trunk,ribs,pelvis,and spine）,T-score,Z-score,lean body mass,limb skeletal muscle index（including ASM/height2,ASM/weight,ASM/BMI）,irisin,bone gamma-carboxyglutamic acid-containing protein（OCN）,myostatin,insulin-like growth factor-1（IGF-1）,type Ⅰ procollagen N-terminal peptide（PIMP）,type Ⅰcollagen carboxy-terminal peptide（CTX）,osteoprotegerin（OPG）,receptor activator of nuclear factor κB ligand（RANKL）,testosterone（T）,and estradiol（E₂）were measured.Results:1.After 24 weeks of aerobic combined with resistance exercise intervention,the calf circumference and appendicular skeletal muscle mass index（ASM index）of the exercise group（EG）significantly increased（P<0.05）,while waist circumference significantly decreased（P<0.05）.There were no significant changes in height,weight,BMI,waist circumference,calf circumference,lean body mass,and ASM index of the control group（CG）（P>0.05）.2.After 24 weeks of aerobic combined with resistance exercise intervention,the upper limb bone density,lower limb bone density,total body bone density,T-score,and Z-score of the EG significantly increased（P<0.05）,while the pelvic bone density significantly decreased（P<0.05）.The trunk bone density,spinal bone density,total body bone density,and T-score of the CG significantly decreased（P<0.05）.The differences in upper limb bone density,lower limb bone density,and total body bone density between the EG and CG were significantly greater（P<0.05）.3.After 24 weeks of aerobic combined with resistance exercise intervention,the serum levels of irisin and osteocalcin in the EG significantly increased（P<0.01）,while the serum levels of bone protective factor,RANKL,estradiol,and the ratio of RANKL/bone protective factor significantly decreased（P<0.05）.The serum levels of bone protective factor and estradiol in the CG significantly decreased（P<0.05）.The serum levels of calcium-binding protein in the EG were higher than those in the CG（P<0.05）,while the serum levels of myostatin and CTX in the EG were lower than those in the CG（P<0.05）.The differences in serum irisin and osteocalcin levels between the EG and CG were significantly greater（P<0.05）,while the differences in serum RANKL and RANKL/bone protective factor ratios were significantly smaller（P<0.05）.4.The correlation analysis results showed that irisin was negatively correlated with age（r=-0.388,P=0.037）and positively correlated with upper limb bone density（r=0.494,P=0.006）,lower limb bone density（r=0.582,P=0.001）,trunk bone density（r=0.393,P=0.035）,pelvic bone density（r=0.436,P=0.018）,total body bone density（r=0.485,P=0.008）,and T-score（r=0.468,P=0.010）.The difference in serum irisin level was positively correlated with the difference in upper limb bone density（r=0.414,P=0.026）,total body bone density（r=0.453,P=0.014）,and calf circumference（r=0.400,P=0.031）.Conclusion:Aerobic combined with resistance exercise for 24 weeks can improve body composition,body shape,increase bone density,and improve bone metabolism in postmenopausal women;Aerobic combined exercise can effectively increase serum irisin levels in postmenopausal women,and bone density changes are correlated with serum irisin levels.