Cardiovascular adaptation to training load in endurance athletes: a longitudinal study

Abstract

Background and Aims Prior studies on cardiac remodelling associated with exercise have relied on self-reported data of uncertain accuracy. In the present study, exercise duration and intensity were objectively quantified using heart rate (HR) monitors in athletes, and these metrics were correlated with cardiac magnetic resonance findings. Methods Young (16-23 years, n = 69) and middle-aged (45-70 years, n = 82) male endurance athletes with >= 80% of training sessions recorded via chest-worn HR monitors over 3 months were included. Training duration, session count, and intensity (classified into five HR zones and expressed as Edwards training impulse in arbitrary units) were analysed. Cardiac magnetic resonance measured indexed left/right ventricular volumes, ejection fraction, and left ventricular mass. Results Younger athletes trained more than older athletes [169 (127-209) vs 78 (49-114) hours; 23 129 (17 880-28 305) vs 12 620 (7168-17 607) arbitrary units; both P 6 or >9 metabolic equivalent of tasks to describe intense activity. Training duration (r > .33, P .29, P < .05 for all) correlated with cardiac dimensions, but the duration always outperformed intensity. Time spent in lower HR zones (1 and 2) correlated more with cardiac dimensions than higher-intensity training. Partial least squares analysis identified training duration in Zones 1&2 and 3 and age as key determinants of cardiac remodelling, whereas intensity was not a significant determinant of cardiac dimensions. Conclusions Objective exercise quantification reveals new insights into cardiac remodelling, highlighting total exercise duration as a primary determinant of left/right ventricular volumes, independent of intensity. Traditional questionnaire-based methods may overlook these relationships.Funding The Master@Heart trial is supported by the Fonds Wetenschappelijk Onderzoek (FWO-TBM, T003717N). The Pro@Heart study is supported by unrestricted grants from Boston Scientific Belgium and Abbott Belgium. R.W. is a clinical research fellow funded by Fonds Wetenschappelijk onderzoek Vlaanderen. A.L.G. received an investigator grant from the National Health and Medical Research Council— Australian Government. Acknowledgements We would like to explicitly thank TrainingPeaks for providing us with their online platform to collect training data from both Pro@Heart and Master@Heart athletes for analysis