| ORIGINAL PAPER : The effects of aerobic treadmill exercise training on insulin resistance and bone metabolic turnover in diabetes mellitus rats |
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| Abstract |
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The purpose of this study is to verify the effect of exercise on bone mass reduction generated by diabetes mellitus (DM) by imposing an 8-week aerobic treadmill exercise to DM-induced rat model and reviewing DM related factors and bone metabolic markers. This study involved thirty 7-week-old, male Sprague-Dawley (SD) rats and divided them into three groups of control (C,n = 10), DM (DC, n = 10), and DM+exercise (DE, n = 10) comprising ten rats each. Diabetes mellitus in the DM group was induced by streptozotocin (STZ). Aerobic exercise was implemented 30 min a day, 5 times a week for 8 weeks. Average exercise intensity was 10m/min from the 1st to the 4th week, and 12m/min from the 5th to the 8th week on 0 percent slope. Consequently, the body weight of rats decreased significantly due to induced DM (p < .001), and showed a significantly increasing tendency after performing exercise (p < .001). Serum insulin level showed a slightly increasing trend as DM developed (N.S.), and showed a significantly decreasing tread as rats exercised (p < .01). The effect of exercise was not found in HOMA-β-cell. However, blood glucose and HOMA-IR increased significantly by the induction of DM (p < .001), and decreased significantly by performing exercise (p < .001). Bone mineral density (BMD), bone mineral content (BMC), bone length, and bone mass decreased significantly by the induction of DM (p <.001), but showed no significant changes by exercise. Moreover, serum Ca and ALB levels decreased significantly by the induction of DM (p < .05, p < .01), but showed no significant changes by exercise. No significant changes were detected by other blood parameters. Meanwhile, femoral BMD exhibited significant correlations with BMC, bone length, and bone mass (p < .01). Blood glucose showed significant negative correlations (p < .01) and HOMA β-cell showed positive correlations (p < .01) with all femoral parameters. Weight and serum Ca and ALB levels showed significant positive correlations with all femoral parameters (p < .05, p < .01). To sum up the above study results, the blood glucose and insulin resistance of diabetic rats were improved by inducing osteoporosis and implementing low intensity aerobic exercise. However, aerobic exercise alone was insufficient to improve osteoporosis. To improve secondary osteoporosis induced by DM, resistance strength training exercises and others need to be intervened to directly impose physical loads on bones. |
| Key Words:
aerobic treadmill exercise, insulin resistance, bone metabolic turnover, bone mineral density, diabetes mellitus, rats |
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