F-25 Free Communication/Poster - Mitochondrial and Metabolic Responses Friday, May 30, 2014, 1:00 PM - 6:00 PM Room: WB1
The Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) is an index of hepatic insulin resistance (IR). HOMA-IR has been shown to correlate to the hyperinsulinemic euglycemic clamp, a direct measure of skeletal muscle insulin sensitivity (Si). It is unknown whether aerobic exercise affects hepatic IR.
PURPOSE: To assess the effects of aerobic exercise training on liver and skeletal muscle measures of insulin sensitivity/resistance. The secondary objective was to examine body composition determinants of both skeletal muscle and hepatic Si.
METHODS: Subjects were 13 healthy, premenopausal women, body mass index (BMI) 27 ±7 km/m2, and physically untrained. Skeletal muscle Si was determined by hyperinsulinemic euglycemic clamp, liver insulin resistance was determined by HOMA-IR, and body composition was measured with dual-energy X-ray absorptiometry before and after 12 weeks of aerobic training at 80% maximum heart rate.
RESULTS: Results of paired t-tests indicated a significant improvement in skeletal muscle insulin sensitivity (P< 0.05) but not hepatic insulin resistance (P=0.813) following training. Results also indicated significant decreases in total percent body fat, trunk percent fat, and leg percent fat following training. Multiple linear regression model results indicated that trunk percent fat was inversely associated with skeletal muscle Si (standardized regression coefficient -.528 P<0.05) and positively associated with HOMA-IR (.504, P<0.05) before training; however there were no associations between body composition and measures of insulin sensitivity/resistance after training.
CONCLUSION: Aerobic exercise training is accompanied by increased skeletal muscle Si, but no change in hepatic insulin resistance estimated by HOMA-IR. Therefore, HOMA-IR will not capture changes in Si that accompany aerobic exercise. Exercise training alters the relationship between body fat distribution and measures of insulin sensitivity/resistance. Supported by NIH Grant: 5R01DK049779-14; DRC Grant P60DK079626; NIH T-32 2T32DK062710-07 (Obesity Research Training Grant)