Aerobic Training Protects Cardiac Function During Advancing Age: A Meta-Analysis of Four Decades of Controlled Studies

Background In contrast to younger athletes, there is comparatively less literature examining cardiac structure and function in older athletes. However, a progressive accumulation of studies during the past four decades offers a body of literature worthy of systematic scrutiny. Objectives We conducted a systematic review, meta-analysis and meta-regression of controlled echocardiography studies comparing left ventricular (LV) structure and function in aerobically trained older athletes (>45 years) with age-matched untrained controls, in addition to investigating the influence of chronological age. Methods Electronic databases were searched from inception to January 2018 before conducting a random-effects meta-analysis to calculate pooled differences in means, effect size and 95% confidence intervals (CIs). Study heterogeneity was reported using Cochran's Q and I-2 statistic. Results Overall, 32 studies (644 athletes; 582 controls) were included. Athletes had greater LV end-diastolic diameter (3.65 mm, 95% CI 2.66-4.64), interventricular septal thickness (1.23 mm, 95% CI 0.85-1.60), posterior wall thickness (1.20 mm, 95% CI 0.83-1.56), LV mass (72 g, 95% CI 46-98), LV mass index (28.17 g.m(2), 95% CI 19.84-36.49) and stroke volume (13.59 mL, 95% CI 7.20-19.98) (all p < 0.01). Athletes had superior global diastolic function [ratio of early (E) to late (A) mitral inflow velocity (E/A) 0.18, 95% CI 0.13-0.24, p < 0.01; ratio of early (e') to late (a') diastolic annular tissue velocity (e'/a') 0.23, 95% CI 0.06-0.40, p = 0.01], lower A (-8.20 cm.s(-1), 95% CI -11.90 to -4.51, p < 0.01) and a' (-0.72 cm.s(-1), 95% CI -1.31 to -0.12, p = 0.02), and more rapid e' (0.96 cm.s(-1), 95% CI 0.05-1.86, p = 0.04). Meta-regression for chronological age identified that athlete-control differences, in the main, are maintained during advancing age. Conclusions Athletic older men have larger cardiac dimensions and enjoy more favourable cardiac function than healthy, non-athletic counterparts. Notably, the athlete groups maintain these effects during chronological ageing.