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


METHODS
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 (G(120)), and glucose area under the curve (G(AUC)) 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), G(120) (-22.5 vs. -3.6%, respectively), and G(AUC) (-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 G(AUC) 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.


CONCLUSIONS
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.
Prior
Steven J
SJ
Division of Gerontology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. sprior@grecc.umaryland.edu
Joseph
Lyndon J
LJ
Brandauer
Josef
J
Katzel
Leslie I
LI
Hagberg
James M
JM
Ryan
Alice S
AS
D001786:Blood Glucose / Q000032:analysis*; D001823:Body Composition; D050218:Body Fat Distribution; D015444:Exercise / Q000502:physiology*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D013848:Thigh / Q000033:anatomy & histology*; D015431:Weight Loss / Q000502:physiology*
D001786:Blood Glucose; D007328:Insulin