Purpose: The current study evaluated; A) global left ventricular (LV) adaption to endurance vs. resistance training in highly trained male athletes; B) the additional insight into the athlete's heart phenotype provided by modern imaging technologies, and C) the impact of scaling for body size on LV structural data.
Methods: A prospective cross-sectional design was employed to comprehensively assess the athlete's heart in 18 elite endurance-trained (ET), 19 elite resistance-trained (RT) and 17 sedentary control (CT) participants. M-mode, 2D, tissue-Doppler imaging (TDI) and speckle tracking echocardiography (STE) were employed to assess LV structure as well as global and regional LV function including myocardial strain. The indexing of LV structural parameters to body surface area (BSA) was undertaken using simple linear ratio scaling as well as a nonlinear allometric model.
Results: Absolute, ratio and allometrically scaled LV mass was significantly higher in ET [200±34 g; 98±15mm/m2, 42±7mm/m2.7] than both RT [187±31g; 78±15mm/m2 and 36±6 mm/m2.7] and CT [165±32g; 74±11 mm/m2 and 33±6 mm/m2.7] (p<0.05). The predominant LV geometry in the ET was normal (65%) and eccentric hypertrophy (30%). There was no significant difference in LV mass between the RT and CT groups. Apart from a higher stroke volume in ET, compared to RT and CT, there were no significant group differences in global function during systole or diastole. Whilst regional TDI data were not different between groups, longitudinal, basal circumferential and mid radial strain was reduced in RT compared to ET.
Conclusion: In this comprehensive, technical evaluation of the athlete's heart, a larger LV was present in ET even after appropriate body size scaling. Evidence for hypertrophy was lacking in RT. Differences in body size and discrimination of AH from disease pathology can be enhanced by appropriate scaling of data. Further work should evaluate cardiac strain and strain rate in RT athletes.