Exercise Training Improves but Does Not Normalize Left Ventricular Systolic and Diastolic Function in Adolescents With Type 1 Diabetes

Abstract

OBJECTIVETo 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. RESEARCH DESIGN AND METHODSFifty-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. RESULTSExercise 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. CONCLUSIONSThese 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.Regular physical activity has many potential health benefits, and there is strong evidence of its role in the primary and secondary prevention of chronic diseases such as cardiovascular disease and diabetes (1). In particular, exercise training improves exercise capacity and cardiac output by increasing left ventricular function (2-5). Training increases left ventricular stroke volume by enhancing intrinsic cardiac contractility

Impaired ventricular filling limits cardiac reserve during submaximal exercise in people with type 2 diabetes

“…In contrast, LV contractile responses to β-adrenergic stimulation are often [ 29 – 33 ] but not always [ 34 ] reduced in the diabetic heart, providing evidence that impaired systolic responses during exercise could limit cardiac reserve. In addition, a recent paper found that end diastolic volume responses to exercise were blunted, but end systolic volume responses were unchanged in adolescents with type 1 diabetes during supine exercise [ 35 ]. In this context, our finding that the T2D group achieved smaller end-diastolic volumes but almost identical end-systolic volumes to non-diabetic controls, supports the theory [ 14 ] that impaired diastolic filling limits aerobic capacity in people with type 2 diabetes but, at least in uncomplicated type 2 diabetes, systolic dysfunction does not.…”

Poor glycaemic control is associated with reduced exercise performance and oxygen economy during cardio-pulmonary exercise testing in people with type 1 diabetes

“…Indeed, approximately 55% of the shorter total exercise time could be accounted for lowered O 2 uptake, decreased power output and less economical use of O 2 for both at the HRTP and maximum power. Taken this into account, it might be that regular exercise training, which increases these physiological parameters, might have similar potential to neutralise the negative influence of glycaemic control on functional capacity [ 27 ] and even on cardiovascular autonomic regulation [ 28 ].…”

Exercise cardiovascular magnetic resonance: development, current utility and future applications

“…Initial studies utilised turbo field echo planar imaging (EPI) with retrospective gating to acquire short axis cine imaging for biventricular volumes during exercise [67,70,71]. Subsequent studies using retrospective ECG gating have used balanced steady state free precision (bSSFP) sequences [25,81,82,88,89]. Recently, an Ex-CMR study used a 3 T scanner to assess LV volumes similarly used bSSFP sequences to acquire 4 chamber and 2-chamber cines to calculate LV function via Simpson's bi-plane method [86].…”