Reduction in midthigh low-density muscle with aerobic exercise training and weight loss impacts glucose tolerance in older men

Abstract

Context: Intramuscular lipid content increases with aging and obesity and is directly related to impaired glucose tolerance and insulin resistance. Objective: Our purpose was to determine the effects of aerobic exercise training (AEX) with and without weight loss (WL) on midthigh low-density muscle (LDM; a measure of im lipid) and whether changes in LDM impact glucose tolerance in sedentary older men. Design: Forty-six men (60.4 ± 1.1 yr) completed 6 months of AEX (n = 34) or AEX + WL (n = 12) and had oral glucose tolerance tests (OGTTs) and computed tomography measures of LDM and regional abdominal and thigh fat depot areas. Results: At baseline, LDM area directly correlated with fasting plasma glucose (FPG), 120-min glucose (G120), and glucose area under the curve (GAUC) during an OGTT (r = 0.44, r = 0.51, and r = 0.54, respectively, P < 0.01). After the interventions, the AEX + WL group had greater decreases in LDM (-13.5 vs. +1.3%, respectively), FPG (-8.3 vs. +2.1%, respectively), G120 (-22.5 vs. +3.6%, respectively), and GAUC (-17.3 vs. +3.1%, respectively) than the AEX group. In the entire sample, the decreases in LDM correlated with reductions in FPG, G 120, and GAUC during an OGTT(r = 0.31, r = 0.34, and r = 0.41, P < 0.05). Changes in other regional fat depots did not independently correlate with glucose tolerance or insulin responses. Conclusion: AEX + WL is more efficacious than AEX for reducing LDM and glucose tolerance. The improvement in glucose tolerance may be partially mediated by decreases in LDM in older men. Copyright © 2007 by The Endocrine Society.