## 4 Discussion  
Using 3D echocardiography with an automated method to volumetrically parcellate the RV, we were able to show for the first time that ASF inter-seasonal training was associated with physiological RV enlargement with predominant changes occurring in the  
Figure 2: Longitudinal 3D RV regional morphological and functional changes. Abbreviations: EDV: end-diastolic volume, EF: ejection fraction. * \(p<0.05\), ** \(p<0.01\), *** \(p<0.001\) of a paired \(t\)-test comparing the variable before and after training. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Variable** & **Intra-Observer** & **Inter-Observer** \\ \hline
**RV global** & & \\ RV EDV, mL & 5 (3.3\%) & 11 (7\%) \\ RV ESV, mL & 4.1 (5.4\%) & 10.6 (15.3\%) \\ RV EF, \% & 2.4 (4.9\%) & 5.2 (10.2\%) \\ \hline
**RV Inlet** & & \\ RV inlet EDV, mL & 3.3 (4.1\%) & 9.3 (12.2\%) \\ RV inlet ESV, mL & 3.2 (7.8\%) & 6.1 (16.2\%) \\ RV inlet EF, \% & 3.3 (7\%) & 5.1 (10.6\%) \\ \hline
**RV Apex** & & \\ RV apex EDV, mL & 1.8 (5.3\%) & 3.5 (9\%) \\ RV apex ESV, mL & 1.8 (12.9\%) & 3.4 (23.7\%) \\ RV apex EE, \% & 5.2 (9.3\%) & 8.7 (14.8\%) \\ \hline
**RV Outlet** & & \\ RV outlet EDV, mL & 3.4 (10\%) & 9 (22.2\%) \\ RV outlet ESV, mL & 2.1 (10.9\%) & 4.1 (20.4\%) \\ RV outlet EE, \% & 3.2 (7.9\%) & 10.7 (23.3\%) \\ \hline \hline \end{tabular} Mean error values, in the format of absolute and the percentual error in parenthesis. Abbreviations: EDV: end-diastolic volume, EF: ejection fraction, ESV: end-systolic volume.  
\end{table} 
Table 3: Intra- and inter-observer reproducibility test for right ventricular (RV) global and regional 3D volumetric assessment. apical and outlet regions, independently of the field position. The RV remodeling was associated with LV hypertrophy. A proportionate biventricular dilatation with preserved function has been commonly associated with chronic exercise in endurance and mixed-trained athletes [11; 18; 19; 20]. Although strength athletes have been less studied, longitudinal observations suggested that high-intensity strength training could impact the right ventricular structure [21]. ASF, unlike most of the other team sports, implies a heterogeneous combination of static and dynamic exercises that vary according to the player field position (linemen/non-linemen) and to the training timeframe (inter-season physical preparation/competitive season). The dichotomy between linemen and non-linemen players is essentially marked during the competitive season, during which ASF players at the linemen position engage almost exclusively in intense static activity, whereas the non-linemen counterparts experience much higher loads of dynamic exercise. Therefore, studies that have previously analyzed the longitudinal cardiac adaptations to the ASF competitive season, have documented field position-specific LV remodeling [1; 2; 4]. In those studies, linemen players exhibit a higher prevalence of LV concentric hypertrophy close to what was reported in strength athletes [22], whereas non-linemen players are more likely to develop an eccentric LV hypertrophic pattern. To date, only one longitudinal study assessed the RV response to the ASF season using 2D-echocardiography in a US football team. The authors concluded the absence of RV exercise-induced remodeling among ASF players [10]. In the present study, we described in a Canadian ASF team the longitudinal cardiac changes that occurred during their inter-seasonal training, which involved all athletes combined static and endurance exercises. Linemen athletes experienced an increased dynamic component of exercise compared to their static activity during the competitive season, which may have contributed to weight loss and lower systolic blood pressure observed at the end of the inter-season. Conversely, non-linemen athletes who were asked to perform more strength work tended to increase arterial blood pressure, which is regularly associated with ASF participation [6].