Dynamic changes in left ventricular mass and in fat-free mass in top-level athletes during the competitive season

Previous cross-sectional studies have demonstrated that fat-free mass (FFM) is an important determinant of left ventricular mass (LVM) in athletes. However, cross-sectional investigations have not the ability to detect the dynamic adaptation occurring with training. We hypothesized that LVM adapts concurrently with the increase of FFM induced by exercise conditioning. We sought to study the relationship between the variations of LVM and of FFM occurring in top-level soccer players during the season.

Twenty-three male top-level athletes were recruited. LVM was assessed by echocardiography and FFM by dual-energy X-ray absorptiometry. Serial measurements were performed pre-season, after 1 month, at mid- and end-season, and after 2 months of detraining.

LVM significantly increased at mid-season versus pre-season values, reaching the highest value at the end of the season (p < 0.05). While body weight did not vary during the study period, FFM significantly increased (p < 0.05 for mid-/end-season vs. pre-season data). After the detraining, no significant differences were observed between pre-season and detraining echocardiographic data. The only independent predictors of LVM were left ventricular stroke volume and FFM (R = 0.36, p = 0.005; R = 0.35, p = 0.005, respectively). When ΔLVM index was set as dependent variable, the only independent predictor was ΔFFM (R = 0.87, p = 0.002).

Changes in LVM occur in close association with changes in FFM, suggesting that the left ventricle adapts concurrently with the increase of the metabolically active tissue induced by training, i.e. the FFM. Therefore, the dynamic changes in FFM and LVM may reflect a physiological adaptation induced by intensive training.