Association of Fat-free Mass and Training Status with Left Ventricular Size and Mass in Endurance-trained Athletes

Objectives: We sought to study the relationship between left ventricular (LV) size and body composition in male endurance athletes and age-matched control subjects.

Background: Endurance training is associated with increases in both left ventricular mass (LVM) and left ventricular end-diastolic dimension (LVEDD) in athletes. In other populations, LVM is independently predicted by fat-free mass (FFM). We hypothesized that the increase in LV size and mass observed with training may be a normal response to increased FFM.

Methods: Twelve young and 18 older male endurance athletes and 10 young and 18 older untrained men underwent exercise testing, echocardiography, and dual-photon x-ray absorptiometry body composition analysis. Univariate correlates (Spearman) and multivariate determinants of LVM and LVEDD were sought from: height, height(1.4), height(2.7), height(3.0), body surface area (BSA), FFM, weight, and body mass index. Un-indexed and indexed LVM and LVEDD were then compared.

Results: Athletes were of a similar age, weight, and height, but had higher FFM and maximum oxygen uptake than untrained men. Both LVM and LVEDD were correlated with body size, including FFM, BSA, weight, and height (all p < 0.05). On multivariate analysis, FFM was the only independent predictor of both LVM (R(2) = 0.36, p < 0.001) and LVEDD (R(2) = 0.35, p < 0.001). Furthermore, LVM and LVEDD (un-indexed and indexed to BSA and height) were different between athletes and non-athletes, but not when indexed to height(2.7) or FFM.

Conclusions: Both LVM and LVEDD are predicted by FFM in endurance athletes, and when indexed to FFM, no training-related differences were observed. Thus, the extent of LV remodeling (athletic heart) in trained individuals may reflect a normal physiologic response to increased FFM induced by training.