Abstract Body (Do not enter title and authors here):
Background: Angiotensin Converting Enzyme (ACE) Insertion/Deletion (I/D) polymorphisms have been extensively studied to determine their contributions to athletic power, strength and endurance. The impact of these polymorphisms on cardiac adaptations to exercise (Athlete’s Heart) is less well studied, especially in the pediatric population. We aimed to determine the impact of ACE-I/D polymorphisms on cardiac anatomy and exercise performance before and after high-intensity athletic conditioning.
Methods: We completed a single center prospective cohort study of adolescent male basketball players from 2023-2024. Participants underwent echocardiography, cardiopulmonary exercise testing (CPET) and ACE-I/D polymorphism typing (I/I, I/D or D/D) before and after a structured exercise conditioning regimen (school basketball season). Metrics of athletic cardiac change via echocardiography and exercise performance via CPET were compared and then correlated with ACE-I/D genetic phenotype. Univariable and multivariable regression analyses were used to compare demographic, echocardiographic, and exercise parameters before and after conditioning. Wilcoxon rank-sum testing was then used to compare these parameters against different ACE polymorphisms.
Results: The cohort consisted of 40 participants (median age: 15.7 (14.3-16.8 years), 47% African American) with 36 completing final assessment. Skeletal muscle mass (105 to 107 % predicted, p=0.02) and hand grip strength (37 to 44 lbs, p=0.0007) changed from baseline to final. By echocardiography, LV end-systolic volume (59 to 62 mL/m², p=0.004) and aortic root dimension (2.08 to 2.1 cm, p=0.04) increased. By CPET only peak heart rate (177 to 180 bpm, p=0.001) and peak RER (1.24 to 1.28, p=0.002) improved following conditioning. When comparing ACE-I/D phenotypes, mitral valve E/A ratio and BMI were significantly correlated with ACE phenotypes, with ACE-I/I showing higher mitral E/A ratio, VO₂ at anaerobic threshold and ACE-I/D showing higher BMI.
Conclusion: Post-conditioning improvements including skeletal muscle mass, LV ESV and aortic root size were noted. Markers of physical performance including peak VO₂ did not improve following the basketball season. ACE polymorphisms did not significantly predict cardiac anatomic changes or peak exercise performance in response to training however it may inform endurance exercise capacity and at the anerobic threshold through improvements in diastolic function.