Diastolic intraventricular pressure gradients (IVPGs) are a measure of the ability of the ventricle to facilitate its filling using diastolic suction. We assessed 15 healthy young but sedentary subjects age <50 years (Young, age 35±9 yrs), 13 healthy but sedentary seniors age >65 years with known reductions in ventricular compliance (Elderly Sedentary, age 70±4 yrs), and 12 Masters athletes age >65 years previously shown to have preserved ventricular compliance (Elderly Fit, 68±3 years). Pulmonary capillary wedge pressure (PCW) and echocardiography measurements were performed at baseline, during load manipulation by lower-body negative pressure at -15 mmHg and -30 mmHg, and after saline infusion of 10 ml/kg and 20 ml/kg (Elderly), or 15 ml/kg and 30 ml/kg (Young). IVPGs were obtained from color M-mode Doppler echocardiograms. Baseline IVPGs were lower (1.2±0.4 vs. 2.4±0.7 mmHg, p<0.0001) and the time constant of pressure decay (tau₀) was longer (60±10 vs. 46±6 ms, p<0.0001) in Elderly Sedentary than in Young subjects, with no difference in PCW. While PCW changes during load manipulations were similar (p=0.70), IVPGs changes were less prominent in Elderly Sedentary than in Young subjects (p=0.02). Changes in stroke volume and IVPGs during loading manipulations correlated (r=0.96, p = 0.0002). PCW and tau₀ were strong multivariate correlates of IVPGs (p<0.001 for both). IVPG response to loading interventions in Elderly Sedentary and Elderly Fit subjects was similar (p=0.33), despite known large differences in ventricular compliance. The ability to regulate IVPGs during changes in preload is impaired with aging. Preserving ventricular compliance during aging by life-long exercise training does not prevent this impairment