Aim: The aim of the study was to evaluate in 263 competitive athletes possible correlations between changes induced by different sport activities in left ventricular (LV) structure and cardiac response during maximal physical effort.
Methods: A total of 160 top-level endurance athletes (ATE; swimmers, runners; 28+/-4 years; 98 male) and 103 strength-trained athletes (ATS; weight-lifters, body-builders; 27+/-5 years; male), selected on the basis of training protocol (dynamic vs. static exercise), underwent standard Doppler echocardiography, heart rate variability analysis and maximal exercise stress test by bicycle ergometry. M- and B-mode echocardiographic LV measurements were determined at rest, while the following functional indexes were assessed during effort: maximal heart rate (HR), maximal systolic blood pressure (SBP) and maximal workload (Watts reached by bicycle test).
Results: The two groups were comparable for age and sex, but ATS at rest showed higher HR, SBP, and body surface area (BSA). By echo analysis, LV mass index and ejection fraction did not significantly differ between the two groups. However, ATS showed increased sum of wall thickness (septum+posterior wall), relative wall thickness and LV end-systolic stress, while LV stroke volume and LV end-diastolic diameter (P<0.01) were greater in ATE. HR variability analysis underlined in ATE increased indexes of vagal tone (P<0.01). During maximal physical effort, ATE showed a better functional capacity, with greater maximal workload (P<0.001) reached with lower maximal HR and SBP. After adjusting for HR, age, sex, BSA and SBP, distinct multiple linear regression models evidenced in ATE independent associations of maximal effort workload with LV end-diastolic diameter (P<0.001), HR (P<0.001) at rest and LV end-systolic stress (P<0.01) were found in ATE. On the other hand, independent direct correlation of SBP max during effort with sum of wall thickness (P<0.001), BSA (P<0.05) and LV end-systolic stress (P<0.001) was evidenced in ATS.
Conclusions: LV structural changes in competitive athletes represent adaptation to hemodynamic overload induced by training and are consistent with different kinds of sport activity. Work capacity during exercise is positively influenced by preload increase in ATE, while increased afterload due to isometric training in ATS determines higher systemic resistance during physical effort.