Endurance Versus Non-endurance Athletes: A Descriptive Discriminant Analysis Based On Echocardiography

Abstract

PURPOSE: To discriminate between endurance and non-endurance athletes according to echocardiographic measures. METHODS: Echocardiographic exams carried out in 201 male and female athletes of diverse sports were studied (Age = 21.7 ± 5.4 years; mean ± SD). A set of fifteen measures was considered: Left ventricular diastolic diameter (LVDD), Left ventricular diastolic diameter index (LVDDI), Interventricular septum thickness (IST), Left ventricular posterior wall thickness (LVPWT), Relative wall thickness (RWT), Left ventricular mass (LVM), Left ventricular mass index (LVMI), Left auricular diameter (LAD), Aortic root diameter (ARD), Inferior vena cava diameter (IVCD), E-wave velocity (EV), A-wave velocity (AV), E/A ratio (EAR), E/e′ ratio (Ee′R) and Right ventricular systolic velocity (RVS). The athletes were categorized in two groups based on the characteristics of their sport discipline: “Endurance” (cardiorespiratory endurance) and “Other” (Non-Endurance). Gender-stratified analyses were performed. MANOVA was firstly implemented to evaluate for a significance difference between endurance and non-endurance athletes. Post-hoc analysis was done by means of Descriptive discriminant analysis; in order to obtain a more reduced set of variables, Stepwise variable selection method was previously performed using the Wilk’s Lambda criterion. Statistical significance was fixed at the 0.05 level. RESULTS: MANOVA was statistically significant in men (Wilk's λ = 0.78, F = 1.81, p = 0.04) and in women (Wilk's λ = 0.63, F = 2.82, p = 0.002). The Stepwise procedure selected two variables in the male (IST and LVDDI) and female (LVMI and LVDDI) strata. The discriminant function was highly significant in both cases (males: Wilk's λ = 0.86, F = 8.59, p < 0.001; females: Wilk's λ = 0.77, F = 13.21, p < 0.001). In men, the standardized discriminant coefficient and the structure coefficient were higher for IST (0.96 and 0.81) than for LVDDI (0.60 and 0.36). And in women, the coefficients corresponding to LVMI (0.62 and 0.84) were similar to the ones of LVDDI (0.59 and 0.81). CONCLUSIONS: In the male athletes, IST showed a more important contribution for distinguishing between the endurance and non-endurance groups than LVDDI. And in the female athletes, LVMI and LVDDI had a comparable contribution.