Cardiac structure and systolic function in resistance-trained athletes versus untrained male adults

Purpose: Research examining the Athlete's Heart has often focused on endurance athletes, yet no clear consensus has emerged on the cardiac adaptations observed in resistance-trained athletes. The purpose of this study is to examine cardiac structure and systolic function in resistance-trained athletes compared to untrained individuals.

Methods: An observational cross-sectional study conducted echocardiographic examinations on male resistance-trained athletes (n = 12; body mass: 93 ± 19 kg [95%CI 82-104]) and age-matched untrained volunteers (n = 12; body mass: 80 ± 7 kg [95%CI 76-84]). Resting blood pressure and anthropometrics were gathered to allow indexing of cardiac parameters to body size and composition.

Results: Compared to untrained individuals, resistance-trained athletes had greater septal (resistance-trained: 1.2 ± 0.1 cm; untrained: 0.9 ± 0.1 cm; p < 0.001), and posterior (resistance-trained: 1.2 ± 0.1 cm; untrained: 0.8 ± 0.1 cm; p < 0.001) wall thickness, and absolute left ventricular mass (resistance-trained: 275 ± 50 g; untrained: 162 ± 25 g; p < 0.01). These differences in left ventricular mass remained significant after accounting for body size and composition (p < 0.01). Cardiac dimensions of the resistance-trained athletes are greater than the normative range described in current literature. Significant differences in functional parameters including stroke volume, E/A ratio and LV end-systolic wall stress were also observed (p < 0.05).

Conclusion: Both structural and functional differences in cardiac measures are apparent when comparing those engaged in chronic resistance-trained to untrained individuals. Furthermore, despite these structural differences, no significant impairment in left ventricular function was observed. However, whilst the cardiac dimensions of most resistance-trained athletes do not exceed the upper limits for physiological hypertrophy the exact mechanism for these differences is unclear and warrants further investigation.