Introduction: The complex phenomenon of the athlete’s heart (AH) describes the chronic physiological structural and functional adaptation secondary to repeated exposure of an acute exercise stimulus. Sources of Data: This narrative review is based on published evidence. Areas of agreement: Highly trained athletic individuals frequently display cardiac parameters which are suggestive of an AH and can exceed the traditional ‘normal’ limits. Area of controversy: The physiological processes underpinning the extent of cardiac adaption and how this is closely linked to exercise type, but also sex, ethnicity, and body size. Growing points: Since its seminal description by Morganroth and colleagues in 1975, our understanding of the AH has evolved in tandem with improvements in cardiac imaging techniques alongside the exploration of more diverse athletic populations. This narrative review aims to provide a balanced discussion of the multi-factorial nature of structure and function of the AH with specific reference to the unique physiological exercise stimuli. Areas timely for developing research: Despite great interest in cardiac adaptations across a broad spectrum of athletic populations, future research designs should consider the use of new and novel imaging techniques to enhance our understanding of the acute cardiovascular responses which ultimately mediates such adaptations, especially in athletic populations underrepresented in the literature.

Background: Elite cycling can be dichotomised into road (endurance cycling) and track (sprint cycling) events that are associated with different training components and athlete physiology. Evidence of disproportionate right ventricular (RV) remodelling in endurance athletes places importance on defining physiological and athletic phenotypes. Therefore, the elite cyclist serves as an ideal model to study training-specific adaptations in the right heart. Methods: One hundred and eighty-six (110 males and 76 females) elite international-level cyclists (mean age 23 ± 5 years) were grouped by discipline (endurance cycling and sprint cycling) and sex (male cyclists and female cyclists). RV and right atrial (RA) structure and function was assessed with 2D, tissue Doppler, and strain echocardiography. Structural data were scaled allometrically to body size. Group comparisons were made with a two-way ANOVA. Results: Significantly larger absolute and scaled RV and RA structural values were seen in male and endurance cyclists (RV end diastolic area index: male endurance 14 ± 2 cm²/m², male sprint 13 ± 2 cm²/m²) than female and sprint cyclists (female endurance 13 ± 2 cm²/m², female sprint 11 ± 2 cm²/m²), respectively. Endurance training exposure was significantly correlated to structural parameters (RA area index: r = 0.53; p < 0.001). Sex and discipline showed significant impact on resting RV function with reduced RV strain values in male and endurance cyclists (RV basal strain: male endurance −17.5 ± 4.0%, male sprint −19.4 ± 4.6%) compared to female and sprint cyclists (female endurance −19.9 ± 3.9%, female sprint −22.1 ± 5.1%), respectively. There were no significant correlations between training exposure and resting RV function. Conclusions: Athlete sex and cycling discipline exert significant effects on RV and RA structure and function in elite cyclists. The strong correlations observed between endurance training exposure and right heart structure emphasise the importance of consideration of sporting discipline in elite athletes.

Background: Structural and functional adaptation of the heart to chronic exercise is dependent on multiple factors, including the volume and type of training, and has direct implications for pre-participation cardiac screening (PPCS). Sailing is a unique multi-training modality sport with limited prior description of cardiac adaptation to training. The aims of this study are (1) to describe electrocardiogram (ECG) changes in sailors, informing PPCS guidelines; (2) to assess structural and functional cardiac changes in sailors; and (3) to examine sex- or discipline-specific cardiac adaptations in sailors. Methods: Seventy elite sailors (33 females) underwent standard ECG and echocardiography. Echocardiographic data were compared to population norms and analysed by sex and sailing discipline based on training type: isometric (IG), pumping (PG), and movement (MG). Results: One sailor presented with abnormal ECG findings (T wave inversion) which warranted further investigation. Primary training-related ECG changes noted were early repolarisation (24%) and sinus bradycardia (30%). The left ventricular volume index was dilated in 18% of all sailors compared to reference values, with similar findings noted on right ventricular parameters for 22% of the study population, although in males only. The impact of predominant training stimulus (IG, PG, MG) did not mediate differences in the structure of any cardiac chambers (p > 0.05). Ejection fraction was lower in the PG (Δ4%, p ≤ 0.001), whereas global longitudinal strain was higher (Δ2%, p = 0.02) compared to MG and IG. Conclusions: Elite-level sailors present with electrical and structural cardiac phenotypes associated with exercise adaptation, with dilation of both left- and right-sided chambers. These data should be considered when interpreting results of PPCS in male and female sailors from different, specific disciplines.