Effect of resistance exercise on myokines and muscle functions in type 2 diabetes and aging

Abstract

Skeletal muscle has recently been recognized as an endocrine organ that produces and releases various cytokines termed myokines that are involved in the regulation of several physiological and metabolic pathways. Myokines are identified as cytokines and other peptides that are produced, expressed and released by muscle fibers and exert autocrine, paracrine or endocrine effects. These findings that the muscle derived myokines provide a conceptual basis and a whole new paradigm for understanding how muscle communicates with other organs, such as adipose tissue, liver, pancreas, bone, and brain. However, there was not enough evidence regard to evaluate the effect of resistance exercise on myokines in diabetes and aging model. In this dissertation, three-part of experiments were performed as follows

1) Resistance training in type 2 diabetes rats, 2) Resistance training in aging mice, and 3) Resistance training in aging adults. The purpose was to investigate the effect of resistance exercise on myokines (including irisin and interleukin-15) and muscle functions in diabetes and aging models. In part 1 study, muscle quality and glucose tolerance were significantly improved in training group compared to control group. And IL-15 and irisin levels were significantly higher in soleus muscle of exercise group compared to control group. In addition, there were positive correlations between grip strength and level of myokines in soleus muscle. In part 2 study, muscle mass and muscle strength were increased following resistance training. IL-15 and irisin were significantly increased in soleus muscle and circulating level. In addition, level of myokines and muscle strength has positive association in aging mice model. In part 3 study, muscle strength and muscle functions were significantly improved in trained elderly compared to sedentary elderly. Circulating myokines were significantly increased after 12 weeks of resistance training in trained group compared to their control group. In addition, changes of myokines were positively correlated with improvement of muscle strength in aging participants. Taken together with these results of dissertation, resistance training for aging and diabetic population was the efficient intervention to enhance the myokines and improve the muscle quality.