Geert Kleinnibbelink

Chapter 4 106 Following the explorative analysis, this study examined the impact of sex on cardiac adaptation to training using a longitudinal design. This design markedly differs frommost previous studies that have adopted a cross-sectional design, including a heterogeneous groups of athletes, and generally not using allometric scaling. 10, 25-29 Our data showed larger LV structural adaptation in female rowers, which remained present upon allometric scaling. These distinct adaptations cannot relate to differences in lifetime exposure to elite athlete level training, since both groups do not differ in age (males 26.3±4.3y versus females 26.6±1.9y, p=0.84). Alternative explanations for the distinct remodelling might be hormonal, molecular and/or genetic mechanisms. However, these mechanisms are not fully understood yet and represent topics for future research. 9 An important limitation is the relatively low sample size for female rowers within this analysis. Nonetheless, our study was sufficiently powered to detect a significant effect between sexes in adaptation. We performed post hoc calculations and found that our study has a statistical power of 0.51-0.64 to detect sex differences in LV mass and LV diameter. At least, our findings highlight the importance for future research to better understand and establish potential sex differences in cardiac adaptation in response to exercise training. Clinical relevance. The observation of no further adjustment in RV remodelling seems relevant as RV enlargement may overlap with the pathological dilation of the RV in patients with an arrhythmogenic RV cardiomyopathy. Previous studies have related RV remodelling in the already highly trained athlete to potential clinical problems. Our work suggests that even high volumes of exercise does not automatically lead to further remodelling of the RV, despite structural changes in the LV. However, a potential limitation is that subjects followed an individually determined exercise training protocol to increase training volume, which makes it difficult to relate cardiac remodelling to specific determinants of the exercise training protocol and at a cohort level. Also, we did not perform cardiopulmonary exercise testing to examine the level of fitness following exercise training. However, all individuals significantly increased their training volume, highlighting that additional cardiac remodelling is possible upon increases in training volume. Our study may have further clinical relevance, since we specifically explored remodelling in female elite athletes. Participation of females in elite sports has increased significantly over the past decades. Current work on the athlete’s heart, leading to insight