The Joint Effect of Insulin Sensitivity and Physical Activity on the Skeletal Muscle Mass and Performance

Purpose: European working group on sarcopenia in 2010 recommended that using gait speed, grip strength and muscle mass for diagnosis of sarcopenia. There are many well-known risk factors may lead to the occurrence of sarcopenia, such as inactivity, nutrition deficiency, neurodegenerative diseases, cachexia and endocrine disorders. But their combined effects on sarcopenia components still remain unclear. Therefore, this study aimed to explore the joint effect of physical activity and insulin sensitivity associated with skeletal muscle mass and performance in Taiwanese metropolitan elders. Methods: A community-based cross-sectional survey of a sample of 1,347 elders was conducted in Taichung City, Taiwan in 2009. Among them, 844 elders with complete examination of dual energy X-ray absorptiometry, fasting blood glucose, and serum insulin level were included. Insulin sensitivity was estimated with Homeostasis Model Assessment (HOMA-IR) equation. Elders were classified into 3 groups according to tertiles of insulin sensitivity. Physical performance was assessed according to grip strength and walking speed. Physical activity status was assessed by self-reported questionnaire. Chi-square test, Student's test, and general linear model were applied for statistical analysis. Results: Elders with the highest tertile of insulin sensitivity had the highest mean weight, BMI, and waist circumference; and the lowest mean weight-adjusted skeletal muscle index (SMI) than the other two groups. After multivariate adjustment, the mean height- and weight-adjusted SMI for elders in the highest tertile of insulin sensitivity were 6.7 kg/m^2 and 27.9%, respectively, which were significantly lower than those of elders in the lowest tertile of insulin sensitivity. Compared to physically active elders with the lowest tertile of insulin sensitivity, physically inactive elders with the highest tertile of insulin sensitivity had a significantly lower means in heightadjusted SMI, weight-adjusted SMI, gait speed, and grip strength by 0.48 kg/m^2, 1.99%, 0.25 m/s, and 2.4 kg, respectively. Conclusion: Our study identified significantly joint effect of physical inactiveness and low level of insulin sensitivity on decreased SMI, gait speed, and grip strength. These results suggest that physical inactiveness and insulin insensitivity potentially enhance the risk of sarcopenia in Taiwanese metropolitan elders.

並列關鍵字

insulin sensitivity ； physical activity ； sarcopenia

國際替代計量

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