Rats selectively bred for low (LCR) or high (HCR) intrinsic running capacity simultaneously present with contrasting risk factors for cardiovascular and metabolic disease. However, the impact of these phenotypes on left ventricular (LV) morphology and microvascular function, and their progression with aging, remains unresolved. We tested the hypothesis that the LCR phenotype induces progressive age-dependent LV remodeling and impairments in microvascular function, glucose utilization and β-adrenergic responsiveness, compared to HCR. Hearts and vessels isolated from female LCR (n=22) or HCR (n=26) were studied at 12 and 35wks. Non-selected N/NIH founder rats (11wks) were also investigated (n=12). LCR had impaired glucose tolerance and elevated plasma insulin (but not glucose) and body-mass at 12wks compared to HCR, with early LV remodeling. By 35wks, LV pro-hypertrophic and GLUT4 gene expression were up- and down-regulated, respectively. No differences in LV β-adrenoceptor expression or cAMP content between phenotypes were observed. Macrovascular endothelial function was predominantly nitric oxide (NO⋅)-mediated in both phenotypes and remained intact in LCR for both age-groups. In contrast, mesenteric arteries revealed significant contributions of both endothelial-derived hyperpolarizing factor (EDHF) and NO⋅ to microvascular endothelial function, which was impaired in LCR rats regardless of age. At 35wks, EDHF-mediated relaxation was impaired whereas the NO⋅ contribution to relaxation is intact. Further there was reduced β2-adrenoceptor responsiveness in both aorta and mesenteric LCR arteries. In conclusion, diminished intrinsic exercise capacity impairs systemic glucose tolerance and is accompanied by progressive development of LV remodeling. Impaired microvascular perfusion is a likely contributing factor to the cardiac phenotype.