Exercise training and the cardiovascular consequences of type 2 diabetes and hypertension - Plausible mechanisms for improving cardiovascular health

The coexistence of type 2 diabetes and hypertension is especially damaging to cardiovascular health. Most trials of exercise training for these conditions have focused on glycemic control and blood pressure reduction. Less is known about the effects of exercise on the cardiovascular consequences of diabetes and hypertension. This article reviews the available evidence and plausible mechanisms by which exercise training may improve the cardiovascular health of persons with type 2 diabetes and hypertension and provides practical guidelines for exercise prescription. A MEDLINE search was performed for January 1985 to June 2002. Bibliographies from relevant articles, professional society clinical practice guidelines, and books were also reviewed. Because few large, randomized trials exist on these topics, meta-analyses, smaller trials, nonrandomized trials, and animal studies were also considered. Data quality was determined by publication in peer-reviewed journals or professional society literature. Type 2 diabetes and hypertension result in abnormalities in central and peripheral parameters of cardiovascular structure and function. Evidence for an exercise training benefit is strongest for improvements in endothelial vasodilator function and left ventricular diastolic function. The data for exercise training's improvement of arterial stiffness and system inflammation and reduction of left ventricular mass are less robust. However, this assertion is based more on a lack of randomized controlled trials rather than data to the contrary. Exercise training also reduces total and abdominal fat. These changes in body composition mediate improvements in insulin sensitivity and blood pressure and may improve endothelial vasodilator function. The current evidence, albeit not fully confirmed in randomized trials, suggests that the benefits of exercise training go beyond the recognized benefits of glycemic control and blood pressure reduction.