Cardiopulmonary physical fitness and tissue characterization through T1 and T2 mapping: new insights on athlete's heart

Abstract

AIMS: Regular vigorous exercise brings about cardiovascular adaptations, but the relationship between cardiac magnetic resonance-derived T1 and T2 mapping and physical fitness is not fully understood, with conflicting literature results. This study aims to define the associations between cardiorespiratory fitness evaluated using cardiopulmonary exercise testing (CPET) and cardiac remodelling using cardiac magnetic resonance (CMR), including T1 and T2 mapping. METHODS AND RESULTS: We enrolled elite, healthy athletes undergoing pre-participation screening (including personal and family history, physical examination, and 12-lead ECG) who volunteered for maximal CPET and non-contrast CMR with a 1.5T scanner, performed no more than 31 days apart. Our study population comprised 125 athletes: median age 19 16-24.5] years; 65% males; median hours of training 20 15-24.5]; 9% power, 36% endurance, 55% mixed. Overall, female athletes showed less pronounced cardiorespiratory and cardiac morphological remodelling compared to their male counterparts, and endurance athletes exhibited the highest levels of cardiorespiratory fitness and the most pronounced cardiac remodelling of the sport types considered. Greater overall fitness was associated with larger cardiac volumes and mass, and lower T1 and T2 values. In multivariate analysis, sex, sport type, LVMi, EDWT, VO2 max, and peak lactate collectively explained ~27% of the variation in T1 values. CONCLUSION(S): Cardiac remodelling in athletes appears to be influenced by training load, sex, and sport type. In this study, we demonstrate for the first time an association between myocardial tissue characteristics, assessed by mapping, and cardiopulmonary fitness, evaluated through CPET. This finding suggests a potential link between aerobic adaptation and tissue-level myocardial properties. Further studies are warranted to validate these associations and to clarify their role in distinguishing physiological athletic remodelling from early pathological changes. Copyright © The Author(s) 2025. Published by Oxford University Press on behalf of the European Society of Cardiology.