Cardiac Structure and Function in Elite Female and Male Soccer Players

Abstract

Importance: Population-specific normative data are essential for the evaluation of competitive athletes. At present, there are limited data defining normal electrocardiographic (ECG) and echocardiographic values among elite US soccer players.

Objective: To describe ECG and echocardiographic findings in healthy elite US soccer players.

Design, setting, and participants: This cross-sectional study analyzed Fédération Internationale de Football Association-mandated screening sessions performed at US Soccer National Team training locations from January 2015 to December 2019. US women's and men's national team soccer players undergoing mandated cardiovascular screening were included.

Main outcomes and measures: Normal training-related and abnormal ECG findings were reported using the International Recommendations for Electrocardiographic Interpretation in Athletes. Echocardiographic measurements of structural and functional parameters relevant to cardiovascular remodeling were assessed relative to American Society of Echocardiography guideline-defined normal ranges.

Results: A total of 238 athletes (122 [51%] female; mean [SD] age, 20 [4] years; age range, 15-40 years) were included. Male athletes demonstrated a higher prevalence of normal training-related ECG findings, while female athletes were more likely to have abnormal ECG patterns (14 [11%] vs 0 in male cohort), largely accounted for by abnormal T-wave inversions. Echocardiography revealed no pathologic findings meeting criteria for sport restriction, but athletes frequently exceeded normal ranges for structural cardiac parameters responsive to exercise-induced remodeling including body surface area-indexed left ventricular (LV) mass (58 of 113 female athletes [51%] and 67 of 114 male athletes [59%]), indexed LV volume (89 of 115 female athletes [77%] and 76 of 111 male athletes [68%]), and LV wall thickness (37 of 122 female athletes [30%] and 47 of 116 male athletes [41%]). Age-stratified analysis revealed age-dependent increases in LV wall thickness, mass, and volumes among female athletes and LV wall thickness and mass among male athletes.

Conclusions and relevance: These data represent the first set of comprehensive normative values for elite US soccer players and one of the largest sport-specific echocardiographic remodeling studies in female athletes. Abnormal ECG findings were more common in female athletes, while both female and male athletes frequently exceeded clinical normality cut points for remodeling-associated echocardiographic parameters.

Figure 1.. Left Ventricular (LV) Wall Thickness and Remodeling Patterns Among Female and Male Elite Soccer Players

A, The distribution of maximal LV wall thickness is shown for female and male soccer players. Overall, 31% of female athletes and 41% of male athletes had wall thickness above the American Society of Echocardiography–defined normal range. The maximal wall thickness observed was 1.3 cm. B, Patterns of LV remodeling in the study population are shown, stratified based on relative wall thickness and sex-specific LV mass index, according to guideline framework. ULN indicates upper limit of normal.

Figure 2.. Structural and Functional Parameters Among Female and Male Elite Soccer Players

Sex-specific distributions of 6 key structural and functional echocardiographic parameters are shown for members of the US Women’s and Men’s national soccer teams, along with American Society of Echocardiography–defined normal ranges and the percentage falling within and outside the normal range. BSA indicates body surface area; LA A/P, left atrial antero-posterior dimension; LV, left ventricular; LVEDD, left ventricular end-diastolic dimension; LVM, left ventricular mass; RV, right ventricular; RVEDD, right ventricular end-diastolic dimension.

Figure 3.. Differences in Key Left Ventricular (LV) Structural Parameters Across Different Age Groups

Three key structural echocardiographic parameters tightly linked to the process of exercise-induced cardiac remodeling are shown stratified by sex and age group in this sample of elite US soccer players. Values are presented as mean (SD) and percentage of individuals meeting criteria for abnormal measurements (% abnormal). Senior Men’s national team did not participate in screening program during study period. LA indicates left axis; RA, right axis; RV, right ventricular.