| Abstrakt: |
Maximal aerobic power (O2max), body composition, and cardiac dimensions, including left ventricular volume and mass, were evaluated in 39 male marathon runners and 26 sedentary men similar in age and height. The runners were significantly lower in body weight (Wt) and body fat, but similar in lean body weight (LBW) to that of the sedentary men. Both groups were similar in maximal exercise heart rate, whereas the runners were significantly lower in resting heart rates (RHR) and higher in O2max. Absolute dimensions for septal (IST) and posterior (LVPWT) walls were significantly (P < .05) larger in the runners. There was no significant difference between the two groups, however, in the left ventricular mass (LVM) and muscle volume (LVMV) and left ventricular volume (TLVV). There were also no significant differences between the runners and sedentary men with regard to left ventricular end-diastolic and end-systolic dimensions and volumes, stroke volume, and ejection fraction. When the cardiac dimensions, volumes, and mass were expressed relative to body surface area (BSA) and WT, the values for the runners were significantly larger than those of the sedentary men. When the measures were expressed relative to LBW, however, only IST was significantly larger in the runners. The increase in the number of significant differences between the groups when the dimensions were expressed relative to BSA and WT indicates that standardization by these units leads to erroneous conclusions as to the presence and magnitude of cardiac hypertrophy. Although the runners had slightly thicker septum and posterior walls, left ventricular mass was similar between the runners and controls. Our findings suggest that the concept that endurancetraining produces cardiac hypertrophy should be interpreted with caution. |
