Aerobic Fitness is Predicted by Ventricular Size but not Function In Female Youth Athletes

Abstract

The relationship between aerobic fitness, physical maturity, ventricular morphology and function in children is poorly defined. PURPOSE: To define the relationship between aerobic fitness and cardiac morphology and function in children and whether this relationship varies with physical maturity. METHODS: 44 adolescent female athletes (13-18 years) underwent resting 2-D echocardiography for measurements of right ventricular end-diastolic diameter (RVEDD), RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), left-ventricular end-diastolic volume (LVEDV), LV stroke volume (LVSV) and ejection fraction (LVEF) and maximal cycle ergometer testing for determination of maximal aerobic capacity (VO2max). Variables were initially compared across Tanner stage (3-5). Participants were stratified by Tanner stage and grouped by fitness level (high fit, low fit) based on VO2max median split and variables were compared between groups. Finally, multivariate regression was used to determine the independent predictors of VO2max, using Tanner, RVEDD, LVEDV, RVFAC, and LVEF as covariates. RESULTS: No significant differences were identified between Tanner 3, 4, and 5 with respect to VO2max (2.97 v 3.21 v 3.54 L/min, respectively, p=0.18), RVEDD (2.4 v 2.5 v 2.9 cm, p=0.415), RVFAC (47.0 v 43.5 v 42.5 %, p=0.625), TAPSE (2.45 v 2.40 v 2.35 cm, p=0.67), or LVEF (64.0 v 61.0 v 60.5 %, p=0.347), while increases across Tanner stage were noted in LVEDV (76.0 v 76.5 v 85.5 ml, p=0.033), and LVM (95.7 v 99.2 v 124.2, p<0.001). Compared to low fit, high fit participants had significantly greater RVEDD (p=3.0 v 2.4 cm, p=0.002), but not LVEDV (77.5 v 76.0 ml, p=0.319), LVM (110.5 v 100.6 g, p=0.49), LVEF (58.0 v 62.5%, p= 0.192), RVFAC (p=42.5 v 45.0 %, p=0.70), or TAPSE (p=2.4 v 2.4 cm, p=0.97). After inclusion in the multivariable model, VO2max was independently associated with LVEDV (p=0.021), RVEDD (p=0.046), but not Tanner (p=0.79), LVEF (p=0.37) or RVFAC (p=0.48). CONCLUSION: In adolescent female athletes, higher fitness is associated with both increased LV and RV size, but not ventricular function. Similarly, ventricular size increased with physical maturity, while ventricular function did not.