Left ventricular function and mechanics following prolonged endurance exercise: an update and meta-analysis with insights from novel techniques

Background The cardiac consequences of undertaking endurance exercise are the topic of recent debate. The purpose of this review is to provide an update on a growing body of literature, focusing on left ventricular (LV) function following prolonged endurance exercise over 2 h in duration which have employed novel techniques, including myocardial speckle tracking, to provide a more comprehensive global and regional assessment of LV mechanics. Methods Prospective studies were filtered independently following a pre-set criteria, resulting in the inclusion of 27 studies in the analyses. A random-effects meta-analysis was used to determine the weighted mean difference and 95% confidence intervals (CI) of LV functional and mechanical data from pre-to-post-exercise. Narrative commentary was also provided where volume of available evidence precluded meta-analysis. Results A significant overall reduction in LV longitudinal strain ( Ɛ ) n = 22 (− 18 ± 1 to − 17 ± 1%; effect size ( d ) − 9: − 1 to − 0.5%), strain rate n = 10 (SR; d − 0.9: − 0.1.3 to − 0.5 l/s) and twist n = 5 (11.9 ± 2.2 to 8.7 ± 2.2°, d − 1: − 1.6 to − 0.3°) was observed following strenuous endurance exercise (range 120–1740 min) ( P < 0.01). A smaller number of studies ( n = 4) also reported a non-significant reduction in global circumferential and radial Ɛ ( P > 0.05). Conclusion The meta-analysis and narrative commentary demonstrated that a reduction in LV function and mechanics is evident following prolonged endurance exercise. The mechanism(s) responsible for these changes are complex and likely multi-factorial in nature and may be linked to right and left ventricular interaction.