Effects of ageing and training on the human heart

Abstract

The aim of the present studies was to evaluate the effects of ageing and endurance training on the human heart. One hundred and twelve healthy subjects, athletes and non-athletes, between 20 and 80 years of age and two master athletes between 70 and 80 years of age with previous myocardial infarction were investigated. Upright bicycle stress test, Holter-ECG, echocardiography at rest, myocardial perfusion scintigraphy (MIBI-SPECT) and radionuclear angiography at rest and during semi-sitting bicycle leg exercise were performed. Maximal oxygen uptake was measured in the young and old athletes and their controls during treadmill testing and upright bicycle exercise, respectively.

In the healthy, non-athletic men and women between 40 and 80 years of age, myocardial MIBI uptake varied with the highest relative isotope uptake in the apical-lateral part of the left ventricle. In both men and women, higher isotope uptakes were seen in the basal parts of the left ventricle at rest than during maximal physical exercise. Isotope uptake, both at rest and during exercise, was related to gender, age, BMI and thoracic circumference. In the athletes, regional myocardial perfusion, as measured by semiquantitative MIBI-SPECT, differed compared to the healthy sedentary subjects and resulted in uptake defects on the polar maps in the majority of both young and old athletes.

Among the non-athletic subjects, men had an exercise capacity, corrected for body weight, comparable to that of women ten years younger. In both men and women, the decline in exercise capacity averaged 10% per decade. Both the young and old athletes had maximal exercise and aerobic capacities 50% higher than those of healthy, non- athletic controls (p<0.001). The old athletes had an exercise capacity similar to that of non-athletic men 30 years younger. Also, the two master athletes with previous myocardial infarction had maximal aerobic and exercise capacities higher than those of the healthy, age-matched controls.

Ventricular systolic function at rest as estimated by scintigraphic and echocardiographic techniques, showed a slight age-related decline in men but not in women. Left ventricular diastolic function, estimated from the atrial contribution to the total mitral annulus displacement at echocardiographic examination, was negatively correlated with age in both men (r=0.82, p<0.001) and women (r=0.46, p=0.02). The young athletes had higher ejection fraction values at rest than the young and old controls and the elderly athletes (p<0.001). The elderly athletes had better left ventricular systolic and diastolic function, as measured by echocardiographic methods, at rest than the old controls (p=0.001).

During exercise, ejection fraction rose in the non-athletic men between 20 and 70 years of age (p<0.01), in women between 40 and 60 years of age (p<0.01) and in the young and old athletes (p<0.01). In the oldest male and female controls, ejection fraction remained unchanged. Ejection fraction during exercise was higher in both the young and old athletes than in their age-matched controls (p<0.001 and p=0.024, respectively). Left ventricular end-diastolic volume increased during exercise in the young athletes and controls (p<0.05) while it remained unchanged in the old athletes and controls. The old athletes had ventricular arrhythmias and episodes of bradycardia more frequently, but higher heart rate variability than their age-matched controls.