The association between physical activity and cardiac performance is dependent on age: the Copenhagen City Heart Study

Abstract

This study aimed to test the hypothesis that regular physical activity is associated with improved cardiac function measured by tissue Doppler imaging (TDI) in the general population. Within a large prospective community-based population study, cardiac function was assessed in 2221 persons by TDI. Longitudinal displacement (LD), early diastolic velocity (e'), and myocardial performance index (MPI) was obtained by TDI. Linear univariable and multivariable regression analyses were performed in relation to age groups (< 50 years, 50-65 years, > 65 years) and self-reported level of physical activity: I (inactivity), II (light activity), III (moderate activity), and IV (high-level activity). Participants < 50 years in the most active group had significantly better cardiac performance when compared to all other activity levels (higher levels of e', LD, and lower levels of MPI). The findings remained with statistical significance after adjustment for sex, ischemic heart disease, diabetes, hypertension, and body mass index (e' = 11.0, 95% CI (10.4-11.6), p < 0.001; LD = 12.8 (12.3-13.4), p < 0.003; MPI: 0.40 (0.38-0.42), p = 0.02). In age > 65 years, there was a tendency of impaired cardiac function in higher levels of exercise. Interaction analysis revealed that age significantly modified the association between physical activity and cardiac function (p < 0.001). We found a positive association between higher level of physical activity and improved cardiac function in younger persons (< 50 years). In the general population, however, the association interacted with age and amongst persons above 65 years there was a negative association between higher level of physical activity and cardiac function.

Keywords: Cardiac function; Cardiac time intervals; Echocardiography; Exercise; Physical activity; Population study; Tissue Doppler imaging.

Fig. 1

Example of myocardial velocity curve by tissue Doppler imaging. The yellow circle shows the place where the sample is obtained (lateral region of the mitral annulus). Y-axis: myocardial velocity (cm/s). X-axis: time (seconds). The positive peak during systole is marked by s’ on the velocity curve. During diastole, early (e’) and late (a’) diastolic peak is marked. Mitral annular displacement (longitudinal displacement) is calculated from area under the curve during systole (shaded area)

Fig. 2

(Left) Four-chamber gray-scale (bottom) and color tissue Doppler imaging (top) views in end-systole showing the position of the M-mode line used for measurement of cardiac intervals. (Right) Color diagram of the tissue Doppler imaging M-mode of the anterior mitral leaflet. AVC aortic valve closing, AVO aortic valve opening, MVC mitral valve closing, MVO mitral valve opening, IVRT isovolumic relaxation time, IVCT isovolumic contraction time, ET ejection time

Fig. 3

Early diastolic velocity e’ in relation to age group and activity level. Mean and 95% confidence intervals

Fig. 4

Longitudinal displacement (LD) in relation to age group and activity level. Mean and 95% confidence intervals

Fig. 5

MPI (geometric mean and 95% confidence intervals) in relation to age group and activity level. MPI= (IVRT + IVCT)/ET. MPI myocardial performance index, IVRT isovolumic relaxation time, IVCT isovolumic contraction time, ET ejection time. *The p-values in trend analysis for MPI within each age group

Fig. 6

Resting heart rate (RHR, beats per minute) in relation to age group and activity level. *The p-values in trend analysis for RHR within each age group