AIMS: Endurance training may be associated with arrhythmogenic cardiac 
remodelling of the right ventricle (RV). We examined whether myocardial 
dysfunction following intense endurance exercise affects the RV more than the 
left ventricle (LV) and whether cumulative exposure to endurance competition 
influences cardiac remodelling (including fibrosis) in well-trained athletes.
METHODS AND RESULTS: Forty athletes were studied at baseline, immediately 
following an endurance race (3-11 h duration) and 1-week post-race. Evaluation 
included cardiac troponin (cTnI), B-type natriuretic peptide, and 
echocardiography [including three-dimensional volumes, ejection fraction (EF), 
and systolic strain rate]. Delayed gadolinium enhancement (DGE) on cardiac 
magnetic resonance imaging (CMR) was assessed as a marker of myocardial 
fibrosis. Relative to baseline, RV volumes increased and all functional measures 
decreased post-race, whereas LV volumes reduced and function was preserved. 
B-type natriuretic peptide (13.1 ± 14.0 vs. 25.4 ± 21.4 ng/L, P = 0.003) and 
cTnI (0.01 ± .03 vs. 0.14 ± .17 μg/L, P < 0.0001) increased post-race and 
correlated with reductions in RVEF (r = 0.52, P = 0.001 and r = 0.49, P = 0.002, 
respectively), but not LVEF. Right ventricular ejection fraction decreased with 
increasing race duration (r = -0.501, P < 0.0001) and VO(2)max (r = -0.359, P = 
0.011). Right ventricular function mostly recovered by 1 week. On CMR, DGE 
localized to the interventricular septum was identified in 5 of 39 athletes who 
had greater cumulative exercise exposure and lower RVEF (47.1 ± 5.9 vs. 51.1 ± 
3.7%, P = 0.042) than those with normal CMR.
CONCLUSION: Intense endurance exercise causes acute dysfunction of the RV, but 
not the LV. Although short-term recovery appears complete, chronic structural 
changes and reduced RV function are evident in some of the most practiced 
athletes, the long-term clinical significance of which warrants further study.