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-α 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.