Meta Analysis Of The Effects Of Exercise On Bone Mineral Density In Postmenopausal Women

Objective:Osteoporosis has been a public health problem affecting the health of women in the world, especially in the women with an age more than 50 years. In this study, the effects of exercise on bone density of femoral neck, hip and lumbar spine in the postmenopausal women were studied by using Meta analysis. The exercise includes the aerobic exercise, the load bearing movement and the resistance movement.Methods:The key words such as menopause, exercise, bone mineral density were used for retrieving the literatures in the databases such as Chinese CNKI, Wanfang data, Medline, Embase, Cochrane library and Web of Science. The subjects were postmenopausal women who never suffer from osteoporotic fracture. The randomized controlled trials were included and the base line data was comparable in exercise group and control group. The exercise group received exercise intervention, which might be aerobic exercise, bearing movement or resistance movement. The control group did not receive regular exercise. The two groups had not received any other intervention measures affecting bone mineral density. Non-randomized controlled trials and the subjects of the studies receiving other measures intervening bone density were excluded. The bone density of hip, lumbar spine or femoral neck were measured in both groups.The data was analyzed by Revman 5.2.5 from Cochrane. The main analysis process included heterogeneity test, Meta analysis and funnel plot analysis. The heterogeneity of the tests was analyzed by I2 test, there was no significant difference (P>0.1), the fixed effect model was used for Meta analysis; If there was significant difference (P<0.1), a random effect model was used. Potential publication bias was analyzed by funnel plots.Results:After systematic retrieve,347 papers were enrolled. After reading the title and abstract,301 papers were excluded. After reading the full text, another 31 papers were excluded. Finally fifteen trials were eligible for inclusion.935 postmenopausal women were enrolled in this study, including 483 women in exercise group and 452 women in control group. The literatures were published from 1993 to 2013.According to Jadad scoring criteria,9 literatures were high-quality studies and 6 literatures were low-quality studies. The study period was from 5 months to 5 years.(1) In the exercise group, compared with the data before the exercise intervention, there was no statistical significance in the bone mineral density on hip (P=0.64,3 studies including 88 cases), lumber spine bone mineral density(P=0.53,9 studies including 176 cases) and bone density of the femoral neck(P=0.29,4 studies including 93 cases) after the exercise intervention in postmenopausal women.(2)In the control group, there was no significant difference in lumbar spine bone density (P=0.71,9 studies including 194 cases), but there were significant differences in the hip bone mineral density(.P=0.008,3 studies including 88 cases) and bone mineral density of the femoral neck(P=0.02,4 studies including 93 cases) after follow-up.(3) A total of 10 studies including 396 cases were conducted to compare the difference before and after the intervention between the two groups. The result showed that there was a significant difference in the change of lumbar bone mineral density (P<0.0001) between before and after intervention in two groups.(4)A total of 3 studies including 75 cases were involved to compare the difference in the level of osteocalcin before and after the intervention in the two groups. This study showed no significant change in osteocalcin (P=0.51) after intervention in the exercise group, as well as that after follow-up in control group(P=0.09).Conclusions:The results show that the bone mineral density (hip or femoral neck) of the postmenopausal women could decrease gradually, and exercise could not increase the bone mineral density. But the bone mineral density of lumbar spine, hip or femoral neck in the postmenopausal women carrying out regular exercise does not decrease significantly. The results suggest that strengthening exercise is effective in preventing from loss of bone mass and decreasing bone mineral density in postmenopausal women, which may play an important role in preventing bone fracture.