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The effect of high-intensity-resistance training compared with low-intensity exercise on bone mineral density in postmenopausal women: an evidence-based review
Background: Osteoporosis has its highest incidence among postmenopausal women.1 Bone Mineral Density (BMD) correlates with risk of fracture in that, for every standard deviation decrease in BMD, the relative risk of fracture approximately doubles depending on the skeletal site and type of fracture.2 Bone behavior and adaptation are currently predicted by Wolff?s law that states bone will change in response to new forces on it.3 Whether exercise can increase BMD remains ambiguous. The purpose of this meta-analysis and systematic review was to examine the effect of high-intensity-resistance training as compared to low-intensity exercise on BMD in postmenopausal women at the femoral neck and lumbar spine. The hypothesis is that high-intensity-resistance training will be more effective in increasing BMD compared with low-intensity exercise. Methods: Studies eligible for inclusion were peer-reviewed randomized control trials (RCT?s). Postmenopausal women with a BMD T-score from 0 to -2.5 were included in this evidence based review. Areas of interest for this study include the lumbar spine and femoral neck. Individuals with osteoporosis were excluded. Computerized searches of scientific databases were undertaken. The effect size, standard error of effect size, lower-confidence interval, and upper-confidence interval were calculated for individual studies and then pooled. The Q-statistic and p-value were calculated to determine heterogeneity or homogeneity. Results: The original search strategy recognized 12017 studies, of which 50 needed further full-text screening, and the full-texts of 4 articles met the inclusion criteria and were critically analyzed. BMD changes at the lumbar spine demonstrate heterogeneity between studies and BMD changes at the femoral neck demonstrates homogeneity between studies. Statistical analysis of the results found no significant differences in BMD at the lumbar spine or femoral neck when comparing high-intensity resistance training to low-intensity exercise with a small effect size at both the lumbar spine and femoral neck. Conclusion: It is important to advocate and prescribe postmenopausal women with an exercise program achieving adequate skeletal loading through strength training and weight bearing exercises in order to maintain or improve BMD.