Distinct effects of aerobic exercise training and weight loss on glucose homeostasis in obese sedentary men

Abstract

The decline in glucose homeostasis with aging may be due to the physical deconditioning and obesity that often develop with aging. The independent and combined effects of aerobic exercise training (AEX) and weight loss (WL) on glucose metabolism were studied in 47 nondiabetic sedentary older men. There were 14 men in a weekly behavioral modification/WL program, 10 in a 3 times/wk AEX program, 14 in an AEX+WL program, and 9 in the control (Con) group. The 10-mo intervention increased maximal oxygen consumption (VO2max) in both the AEX and AEX+WL groups [0.33 +/- 0.05 and 0.37 +/- 0.09 (SE) l/min, respectively], but VO2max did not significantly change in the WL (0.01 +/- 0.06 l/min) and Con groups (-0.04 +/- 0.05 l/min; P > 0.05). The AEX+WL and WL groups had comparable reductions in body weight (-8.5 +/- 0.9 and -8.8 +/- 1.2 kg, respectively) and percent fat (-5.5 +/- 0.7 and -5.9 +/- 1.1%, respectively) that were significantly greater than those in the Con and AEX groups. Oral glucose tolerance tests showed significant reductions in insulin responses in the AEX, WL, and AEX+WL groups, but the decrease in insulin response in the AEX+WL group was significantly greater than that in the other three groups. The glucose area decreased significantly in the WL and AEX+WL groups but did not change in the Con or AEX groups. There were significant increases in insulin-mediated glucose disposal rates as measured by the hyperinsulinemic (600 pmol.m-2.min-1) euglycemic clamps in the AEX and AEX+WL groups [1.66 +/- 0.50 and 1.76 +/- 0.41 mg.kg fat-free mass (FFM)-1.min-1, respectively] that were significantly greater than those in the WL (0.13 +/- 0.31 mg.kg FFM-1.min-1) and Con groups (-0.05 +/- 0.51 mg.kg FFM-1.min-1; n = 5). These data suggest that AEX and WL improve glucose metabolism through different mechanisms and that the combined intervention of AEX+WL is necessary to improve both glucose tolerance and insulin sensitivity in older men.

Effect of aerobic exercise training on blood pressure sensitivity to dietary sodium in older hypertensives

“…Although the effect of aerobic exercise training on lowering resting BP has been well established, 12,14 the effect of aerobic exercise training on Na þ sensitivity of BP is unknown. In the present study, 21 of the individuals examined did not change their Na þ -sensitivity status after 6 months of aerobic exercise training.…”

Health consequences of obesity in the elderly: a review of four unresolved questions

“…At least four studies [128][129][130][131] showed improvement in metabolic control with better glucose tolerance and increased insulin sensitivity associated with intentional weight loss. Hypocaloric diets were effective with weight loss of up to 10 kg or more.…”

“…114,115 There have been relatively few studies of intentional weight loss to treat weight-related health problems in old age. The evidence that exists suggests that intentional weight loss may be of benefit in controlling cardiovascular risk factors, [128][129][130][131] in reducing medications for weight-related health conditions, 132 and for amelioration of pulmonary disease 133 and OA. 114,115 Even in the elderly, moderate weight loss (ranging in the different studies from few kilograms to as much as 10 kg) may significantly improve the consequences of obesity.…”

Is weight loss the optimal target for obesity-related cardiovascular disease risk reduction?

“…Chronic exercise training, or the summation of acute bouts of exercise, can lead to further improvements in cardiometabolic risk factors, even in the absence of clinically significant weight loss. Indeed, numerous studies have shown that improvements in insulin sensitivity through chronic exercise can occur in the absence of significant weight reduction (13,14,29,30). For example, three months of daily aerobic training in obese men, who consumed compensatory kilocalories equivalent to the amount expended during exercise, resulted in a 30% improvement in insulin sensitivity despite no change in weight (14).…”

“…First, it is well established that increasing physical activity and associated improvements in cardiorespiratory fitness (CRF) are associated with profound reductions in coronary artery disease and CVD mortality, independent of weight or BMI (9,10). Second, acute and chronic exercise is associated with substantial reductions in several cardiometabolic risk factors despite minimal or no change in body weight (11)(12)(13). Third, while WC and visceral fat are reduced consequent to weight loss (14)(15)(16), it is also true that both variables are substantively reduced in response to exercise with minimal or no weight loss (14,15).…”