Diastolic function is strongly and independently associated with cardiorespiratory fitness in central obesity

Abstract

Cardiorespiratory fitness [maximal O2 consumption (VO2max)] is an independent risk factor for type 2 diabetes; but in individuals at risk, factors influencing VO2max are poorly understood. We tested the hypothesis that VO2max is associated with diastolic function [subendocardial variability ratio (SEVR), %], as diastolic function influences myocardial perfusion. We studied 47 men and women with central obesity without diabetes. We measured fitness (VO2max) by treadmill testing and diastolic function (SEVR%) by pulse-wave analysis. We measured other factors influencing this relationship: insulin sensitivity [whole body glucose uptake-to-insulin concentration ratio (M/I)] by hyperinsulinemic euglycemic clamp, fatness by MR imaging and dual-energy X-ray absorptiometry, physical activity energy expenditure (metabolic equivalents of tasks) by the Sensewear Pro2 device, and muscle microvascular exchange capacity (capillary filtration coefficient) by venous plethysmography. Mean age of the subjects was 51+/-9 (SD) yr. VO2max was associated with SEVR% (r=0.50, P=0.001), fatness (r=-0.39, P=0.008), and HbA1c (r=-0.35, P=0.018), but not with whole body glucose uptake-to-insulin concentration ratio, metabolic equivalents of tasks, or capillary filtration coefficient. In regression modeling with age, sex, fatness, and SEVR% as explanatory variables, only age, sex, and SEVR% were independently associated with VO2max (SEVR%--standardized B coefficient=0.37, 95% confidence interval=0.003-0.18, P=0.007). This model identified 46% of the variance in VO2max (R2=0.46, P=0.0001). There was a strong, independent association between VO2max and a measure of diastolic function in sedentary individuals with central obesity.