Exercise-induced reversal of insulin resistance in obese elderly is associated with reduced visceral fat

Abstract

Exercise improves glucose metabolism and delays the onset and/or reverses insulin resistance in the elderly by an unknown mechanism. In the present study, we examined the effects of exercise training on glucose metabolism, abdominal adiposity, and adipocytokines in obese elderly. Sixteen obese men and women (age = 63 +/- 1 yr, body mass index = 33.2 +/- 1.4 kg/m2) participated in a 12-wk supervised exercise program (5 days/wk, 60 min/day, treadmill/cycle ergometry at 85% of heart rate maximum). Visceral fat (VF), subcutaneous fat, and total abdominal fat were measured by computed tomography. Fat mass and fat-free mass were assessed by hydrostatic weighing. An oral glucose tolerance test was used to determine changes in insulin resistance. Exercise training increased maximal oxygen consumption (21.3 +/- 0.8 vs. 24.3 +/- 1.0 ml.kg(-1).min(-1), P < 0.0001), decreased body weight (P < 0.0001) and fat mass (P < 0.001), while fat-free mass was not altered (P > 0.05). VF (176 +/- 20 vs. 136 +/- 17 cm2, P < 0.0001), subcutaneous fat (351 +/- 34 vs. 305 +/- 28 cm2, P < 0.03), and total abdominal fat (525 +/- 40 vs. 443 +/- 34 cm2, P < 0.003) were reduced through training. Circulating leptin was lower (P < 0.003) after training, but total adiponectin and tumor necrosis factor-alpha remained unchanged. Insulin resistance was reversed by exercise (40.1 +/- 7.7 vs. 27.6 +/- 5.6 units, P < 0.01) and correlated with changes in VF (r = 0.66, P < 0.01) and maximal oxygen consumption (r = -0.48, P < 0.05) but not adipocytokines. VF loss after aerobic exercise training improves glucose metabolism and is associated with the reversal of insulin resistance in older obese men and women.

Fig. 1.

Insulin resistance before and after the 12-wk exercise training program. Values represent the means ± SE for 16 subjects. AU, arbitrary units, product of the areas under the glucose and insulin response curves (×10⁷). *Posttraining significantly reduced compared with the pretraining data, P < 0.01.

Fig. 2.

Percent change in total abdominal, subcutaneous, and visceral fat based on computed tomography measures performed pretraining and posttraining. Values represent means ± SE for 16 subjects. *The percent change in total abdominal, subcutaneous, and visceral fat was significantly lower compared with the pretraining measures, P < 0.03.

Fig. 3.

Correlation data showing the association between the change in insulin resistance and the change in visceral fat, based on pretraining to posttraining measures (r = 0.66, P < 0.01). Values are representative of 16 subjects.