The Recreational Athlete’s Heart: Sex-Specific Three-Dimensional Echocardiographic Reference Values in Relation to VO₂peak

Abstract Aim This cross-sectional-study aimed to quantify fitness-specific three-dimensional echocardiographic (3DE) reference values categorized by V̇O2peak to characterize the “recreational athlete’s heart” and its sex-specific adaptations across different fitness-levels. Furthermore, sex-specific association with V̇O2peak was analyzed. Methods 291 healthy participants (mean±SD age: 27±4 years; 44% female) regularly engaging in physical activity were included. Echocardiography was performed with Philips EPIQCVx ultrasound systems to assess 3DE left ventricular (LV), right ventricular (RV), and left atrial (LA) volumes, functional measures, LV mass, and ratios. Cardio-pulmonary exercise testing assessed V̇O2peak (females: 48±6, males: 54±8 ml/min/kg), stratifying participants into three fitness groups: low (L), moderate (M), and high (H) exercise capacity. Results Both sexes showed increases in 3DE end-diastolic volume with fitness (LVEDV/m², median 10th-90th percentile): females: L 73 (61-83), M 80 (71-90), H 88 (80-104); males: L 82 (70-97), M 89 (76-101), H 99 (89-114) ml/m²; with similar trends in RV and LA volumes, LV mass, and stroke volumes. The LV/RV volume (1.1±0.1) and LV/LA volume (females: 2.8±0.4, males: 2.9±0.4) ratio and EF values did not change across fitness-levels, whereas LV mass/volume ratio decreased slightly with increasing fitness without relevant sex differences (L 0.96 (0.87-1.05), M 0.91 (0.83-0.98), H 0.87 (0.80-0.93) g/ml). Conclusions This study establishes sex- and fitness-specific 3DE reference values categorized by V̇O2peak, characterizing the recreational athlete's heart. The V̇O₂peak-associated enlargement was sex-independent; however, at a given V̇O₂peak, men exhibited greater remodeling than women. These results bridge the gap between untrained and elite athletes’ hearts and may enhance 3DE evaluation of recreational athletes.