The Effects Of Different Mode Of Low-intensity Exercise Training On Bone Mineral Density And Bone Metabolism In Postmenopausal Woman

Abstract

PURPOSE: To investigate the effects of 12-month low-intensity resistance training using the elastic band and brisk walking on bone mineral density, body composition, and bone formation marker in postmenopausal woman. METHODS:Thirty-two postmenopausal women (49-63 yr) were assigned to resistance training group (RTG) (n=11; 55.9 ± 4.28 yrs), brisk walking group (BWG) (n=10; 53.2 ± 4.24 yrs) and control group (CG) (n=11; 54.4 ± 3.42 yrs). The training program consisted of resistance exercises using elastic bands and brisk walking for 2 sessions and one hour for each session per week. Total bone mineral density (TBMD), total bone mineral content (TBMC), lumbar spine (LS), femoral neck (FN), body fat, and lean body mass were measured at baseline and after one year training. Duel-energy X-ray absorptiometry (DXA) was used to measure subjects' body composition, regional and total bone mineral density. Serum intact N-terminal propeptide of type I collagen (PINP) and carboxyterminal telopeptide of type I collagen (ICTP) were determined as indices of bone metabolism. The statistical comparisons for the changes of different variables among the three groups were performed by applying one-way ANOVA. RESULTS: The three groups had similar BMD and BC characteristics at baseline. After the training period, there was a tendency of decline in BMD with age, and group differences change were not significant (p > 0.05) except for the spine of BWG. The BWG increased significantly in TBMC (1.4%), lumbar spine (1.3%), and PINP (12%) among groups (p<.05). In body composition, RTG showed significant decrease in body fat in the arm, leg, and total body than the other two groups (p<0.05). Leg lean mass in the walking group increased significantly than both the RTG and CG (p<0.05). CONCLUSIONS: These findings suggest that brisk walking is a medium-impact and weight-bearing exercise which is beneficial on bone mass in postmenopausal woman. Therefore, the impact of exercise training on bone metabolism may depend on the type of exercise during the early phase of training. However, the different mode of low-resistance exercises training on body composition have the different effects which is relatively site specific to the working muscle, thus, brisk walking is more beneficial on the leg and resistance training benefits more towards the whole body.