Geert Kleinnibbelink

Cardiac Remodelling in Olympic Athletes 4 105 sedentary, moderately- and highly-trained individuals. 2, 18-21 Interestingly, concomitant to left-sided structural adaptation, elite rowers also demonstrated augmented LV twist after the increase in training volume. The higher heart rate post-training may partially explain the increase in twist. However, this seems unlikely since no correlation was found between heart rate and twist (r=0.02, p=0.94). Moreover, other functional parameters (also susceptible for differences in heart rate) did not change over time. Although we found adaptation in functional and structural characteristics, both may demonstrate a distinct pattern and are not similarly present. Indeed, the increase in twist was not correlated with changes in LV cardiac morphology (data not shown). Moreover, Weiner et al. observed that exercise training may initially (i.e. 90 days) lead to increases in LV twist, which subsequently disappeared during the chronic training phase (i.e. 39 months). 22 Our finding provides some support for this concept, in that an increase in volume of exercise initially resulted in both functional and structural adaptations, where functional changes may ultimately normalize during the chronic phase when volume of exercise remains the same. Future work is required to better understand these time-dependent adaptations in cardiac remodelling. Despite the disproportionate load on the right versus left ventricle during exercise 4 , we found no adaptation of the right ventricle or atrium. This finding contrasts with our hypothesis, but also with others who addressed right-sided cardiac remodelling in elite athletes. 23, 24 D’Ascenzi et al. reported seasonal variation in RV size in a cohort of top-level basketball and volleyball players. 23 Across three consecutive Olympic Games, Aengevaeren et al. noted that RV remodelling occurred between the first two Olympics Games, followed by a plateau during the subsequent 4 years in a heterogeneous group of athletes (n=50, 17 different sports). 24 These studies, however, are limited by the impact of ageing (i.e. 8-year cycle), large variations in training status across the season, and/or the heterogeneous group of athletes included. The lack of RV remodelling in our study may be explained by achieving a physiological limit for further adaptation prior to the start of the increase in training volume in highly trained rowers due to pericardial constraint. At least, our observations support the presence of distinct remodelling between the left and right side of the athlete’s heart. Future work is required to better understand these differences, specifically focusing on the distinct load placed on both ventricles during exercise, possibly underlying distinct remodelling to (high) volumes of exercise training.