Systolic and diastolic function during cycling at the respiratory threshold between elderly and young healthy individuals

Abstract

The hemodynamic consequences of aging have been extensively investigated during maximal incremental exercise. However, less is known about the effects of aging on hemodynamics during submaximal steady-state exercise. The aim of the present investigation was to compare the hemodynamics of healthy elderly and young subjects during an exercise bout conducted at the gas threshold (GET) intensity. Two groups of healthy, physically active subjects were studied: the elderly group-EG (n = 11; > 60 years old) and the young group-YG (n = 13; < 35 years old). Both groups performed a 5-min rectangular exercise test at the GET intensity. Hemodynamics were measured using echocardiography. The main finding was that stroke volume responses were higher in the YG than the EG (72.5 ± 16.7 vs. 52.4 ± 8.4 ml, respectively). The increased stroke volume capacity in the YG was the consequence of a greater capacity to increase cardiac preload and contractility and, to a lesser extent, to reduce systemic vascular resistance. Importantly, the atrial contribution to ventricular diastolic filling was substantially higher in the YG when compared to the EG.

Figure 1

Hemodynamic data at rest and during exercise conducted at the gas exchange threshold intensity in the elderly (EG, n = 11) and in young (EG, n = 13) groups. Panels (A,C,E) show absolute values; panels (B,D,F) show % changes from rest. HR heart rate, SV stroke volume, CO cardiac output. Values are mean ± SD. *p < 0.05 between groups at the same timepoint.

Figure 2

Hemodynamic data at rest and during exercise conducted at the gas exchange threshold intensity in the elderly (EG, n = 11) and in young (EG, n = 13) groups. Panels (A,C,E) show absolute values; panels (B,D,F) show % changes from rest. PEP pre-ejection period, VET ventricular ejection time, DT diastolic time. Values are mean ± SD. * = p < 0.05 between groups at the same timepoint.

Figure 3

Hemodynamic data at rest and during exercise conducted at the gas exchange threshold intensity in the elderly (EG, n = 11) and in young (EG, n = 13) groups. Panels (A,C,E,G) show absolute values; panels (B,D,F,H) show % changes from rest. VFR ventricular filling rate, VER ventricular emptying rate, MAP mean arterial pressure, SVR systemic vascular resistance. Values are mean ± SD. *p < 0.05 between groups at the same timepoint.

Figure 4

Hemodynamic data at rest and during exercise conducted at the gas exchange threshold intensity in the elderly (EG, n = 11) and in young (EG, n = 13) groups. Panels (A,C,E) show absolute values; panels (B,D,F) show % changes from rest. EDV end-diastolic volume, ESV end-systolic volume, EF ejection fraction. Values are mean ± SD. *p < 0.05 between groups at the same timepoint.

Figure 5

Hemodynamic data at rest and during exercise conducted at the gas exchange threshold intensity in the elderly (EG, n = 11) and in young (EG, n = 13) groups. Panels (A,C,E) show absolute values; panels (B,D,F) show % changes from rest. Evel transmitral filling peak velocity during early diastole, Avel transmitral filling peak velocity during atrial contraction. Values are mean ± SD. *p < 0.05 between groups at the same timepoint.

Figure 6

Hemodynamic (tissue Doppler) data at rest and during exercise conducted at the gas exchange threshold intensity in the elderly (EG, n = 11) and in young (EG, n = 13) groups. Panels (A,C,E,G) show absolute values; panels (B,D,F,H) show % changes from rest. Em mitral valve motion velocity during early transmitral filling, Am mitral valve motion velocity during atrial contraction, Sm systolic myocardial tissue velocity at mitral anulus. Values are mean ± SD. *p < 0.05 between groups at the same timepoint.