The joint association of insulin sensitivity and physical activity on the skeletal muscle mass and performance in community-dwelling older adults

Background: Many well-known risk factors that may lead to sarcopenia are already discovered. However, their combined effects on sarcopenia components remain unclear. This study aims to explore the joint association of physical activity and insulin sensitivity on skeletal muscle mass and performance of Taiwanese elder people from a metropolitan community. Methods: The study sample involved 844 elders who were examined through dual energy X-ray absorptiometry and who underwent tests for fasting blood glucose and serum insulin level. The homeostasis model assessment (HOMA-IR) equation estimated insulin sensitivity. Physical performance was assessed by grip strength and walking speed, while physical activity status was assessed using the questionnaires answered by the participants. Results: After multivariate adjustment, the mean height- and weight-adjusted skeletal muscle indexes (SMIs) for old people in the highest Waite of HOMA-IR values were 6.7 kg/m(2) and 27.9%, respectively, which were significantly lower than those of old people in the lowest tertile of HOMA-IR values. Compared with physically active elders with the lowest tertile of HOMA-IR values, the physically inactive elders with the highest tertile of HOMA-IR values had significantly low means in the height-adjusted SMI, weight-adjusted SMI, gait speed, and grip strength (0.25 kg/m(2) [p = 0.0046], 0.97% [p = 0.0068], 0.24 m/s [p < 0.0001], and 2.37 kg [p = 0.0085], respectively). Conclusion: Our study identified the joint associations of physical inactivity and low insulin sensitivity level on SMI, gait speed, and grip strength. The results provide new information for sarcopenia screening program that target elders who are predisposed to have physical dysfunction in old adults living in community. (C) 2017 Elsevier Inc. All rights reserved.