Moderate‐Intensity Aerobic Training Improves Glucose Tolerance in Aging Independent of Abdominal Adiposity

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Abstract
OBJECTIVE: To test the hypothesis that training‐related improvements in glucose and insulin responses to an oral glucose tolerance test (OGTT) are independent of changes in abdominal adiposity. DESIGN: Adiposity and responses to an OGTT were measured before and after a 4‐month randomized, controlled aerobic training program. SETTING: An academic medical institution. PARTICIPANTS: Sixteen healthy older (73 ± 1 year) men and women. INTERVENTION: Both the training (T) (n = 9) and control (C) (n = 7) groups exercised 4 times a week for 60‐minute sessions. T exercised on mini‐trampolines at 55 to 65% of HRmax (determined from a graded treadmill test) for 1 month and then at 75% for 3 months; C engaged in supervised stretching and yoga. MEASUREMENTS: At baseline and follow‐up, we estimated abdominal fat (from computed tomography and anthropometry), plasma glucose, and serum insulin responses to the OGTT and fasting concentrations of free fatty acids (FFA). RESULTS: Aerobic training resulted in a 16% increase in V̇2 peak and a 24% decrease in FFA in the T group (P <.05), but training had no effect on abdominal fat. In the T group, the glucose response curve shifted to the left, and the incremental area under the glucose curve decreased by 25% (P <.05). This improvement in glucose response occurred, however, only in those with impaired glucose tolerance at baseline and without any observed change in insulin response. No change in any variables occurred in the C group. CONCLUSIONS: Our data suggest that moderate‐intensity aerobic training has a favorable effect on glucose tolerance in older people, independent of changes in abdominal adiposity.