Sedentary Aging and Exercise Effects on LV Function
Does sedentary aging reduce left ventricular (LV) systolic function as assessed by LV longitudinal strain, and does lifelong exercise training preserve it?
This was a cross-sectional study with three groups: 18 sedentary young adults, 31 sedentary seniors, and 31 committed endurance-trained seniors (exercise lasting ≥30 min, ≥4 times per week, ≥25 years). Individuals underwent exercise treadmill stress echocardiography and, within 2 weeks, right heart catheterization (pulmonary capillary wedge pressure) and speckle-tracking echocardiography during three conditions: supine rest, LV unloading (lower body negative pressure), and LV loading (saline infusion). Indices of global LV systolic function (ejection fraction [EF] and preload recruitable stroke work) and LV longitudinal systolic function (peak systolic tissue velocity and longitudinal strain) were measured, along with LV end-diastolic volume and end-systolic pressure (an index of afterload), which were used to adjust longitudinal strain for aging and training-related difference in LV preload and afterload.
There were no significant differences among groups (sex, body mass, size) except higher exercise capacities in exercising seniors and lower systolic and diastolic blood pressures in the sedentary young. Markers of global LV systolic function (EF and preload recruitable stroke work) were unaffected by aging or lifelong exercise. However, more sensitive LV systolic markers were significantly different among groups. Peak systolic tissue velocity was lower in sedentary (10%) and exercising seniors (7%) compared with sedentary young adults. Longitudinal strain was less in sedentary seniors but similar in exercising seniors and sedentary young. Longitudinal strain remained higher in the sedentary young adults compared with seniors when differences in end-systolic pressure were controlled. On the other hand, LV end-diastolic volume eliminated group differences in longitudinal strain between seniors. Independent of aging and lifelong exercise, longitudinal strain was preload dependent.
Sedentary aging reduces LV systolic function, and committed lifelong exercise training attenuates the loss. The benefit of exercise training was due to improved LV diastolic filling rather than favorable changes in afterload.
Exercise is good for the heart. This study further characterizes the morphological and functional changes that occur with aging and lifelong endurance exercise. Global measures of LV function, such as EF, are usually preserved in healthy aging so may not reveal subtle changes in LV systolic function. Longitudinal strain by speckle tracking images appears to be sensitive to changes in LV systolic function when LV loading conditions are controlled.
Keywords: Exercise, Ventricular Function, Left, Aging, Echocardiography, Stress, Echocardiography, Cardiac Catheterization, Stroke Volume, Systole, Diastole, Blood Pressure, Pulmonary Wedge Pressure, Lower Body Negative Pressure
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