Exercise Training Improves but Does Not Normalize Left Ventricular Systolic and Diastolic Function in Adolescents...

To determine the impact of 20 weeks of exercise training in aerobic capacity on left ventricular function and glycemic control in adolescents with and without type 1 diabetes.

Fifty-three adolescents with type 1 diabetes (aged 15.6 years) were divided into two groups: exercise training (n = 38) and nontraining (n = 15). Twenty-two healthy adolescents without diabetes (aged 16.7 years) were included and, with the 38 participants with type 1 diabetes, participated in a 20-week exercise-training intervention. Assessments included VO_2max and body composition. Left ventricular parameters were obtained at rest and during acute exercise using MRI.

Exercise training improved aerobic capacity (10%) and stroke volume (6%) in both trained groups, but the increase in the group with type 1 diabetes remained lower than trained control subjects. Increased stroke volume in adolescents with type 1 diabetes resulted from greater left ventricular contractility (9% increase in ejection fraction and an 11% reduction in end-systolic volumes) and, to a lesser extent, improved left ventricular filling (6%), suggesting that impaired diastolic function can be affected by exercise training in adolescents with type 1 diabetes. Insulin use decreased by ∼10%, but no change in glycemic status was observed.

These data demonstrate that in adolescents, the impairment in left ventricular function seen with type 1 diabetes can be improved, although not normalized, with regular intense physical activity. Importantly, diastolic dysfunction, a common mechanism causing heart failure in older subjects with diabetes, appears to be partially reversible in this age group.