Background: It is unclear whether the beneficial effects of habitual exercise on insulin resistance are due to concomitant weight loss, changes in diet or whether they are simply related to the transient effects of the last bout of exercise. Moreover, patients with coronary artery disease (CAD) have not been studied.
Design: Randomized controlled trial.
Methods: To determine the effects of exercise training on insulin resistance (i.e. low insulin sensitivity) in CAD patients without diabetes independent of changes in weight, diet or the effect of acute exercise, 29 patients were randomized to 12 weeks of supervised exercise training and 26 to usual activity. Insulin sensitivity was determined at 72 h following their last bout of exercise using the minimal model technique. Weight was held constant by adjusting caloric intake.
Results: Following the intervention, peak oxygen uptake increased by 0.18+/-0.14 l/min in the exercise training group, which was significantly higher (P<0.0001) than that in the usual activity group (0.02+/-0.14 l/min). Insulin sensitivity did not change significantly within or between groups during the study [exercise training -0.24+/-1.15 x 10(4)/min and usual activity 0.06+/-0.67 x 10(4)/min/(microU/ml)].
Conclusions: Twelve weeks of moderate exercise training in the absence of weight loss did not result in significant change in insulin resistance in patients with CAD.