Cardiac structure and function of elite Australian jockeys differs to the general population: An observational cross-sectional study.

Abstract

Background The objective of this study was to compare measures of cardiac structure and function of professional jockeys to that of the general population. To determine if there are differences in heart structure and function detected using echocardiography in registered Australian jockeys when compared to the general population. It was hypothesised that remodelling of cardiac structure and function would be detected in jockeys when compared to the general population. The cardiovascular changes resulting from the physical demands of thoroughbred racing remain unexplored in this population of athletes. Australian jockeys and participants from the general population underwent two-dimensional (2D) echocardiography, which included all standard views and measurements in accordance with the American Society of Echocardiography guidelines. Each measurement was compared between groups using a Mann-Whitney U test. Results Forty-six Australian jockeys (35 ± 12 years) and thirty-three age- and gender-matched (36 ± 13 years) participants from the general population participated in this study. Jockeys were shorter (1.64 ± 0.07 vs. 1.75 ± 0.09m, p < 0.001), lighter (56.5 ± 6.0 vs. 74.2 ± 12.9kg, p < 0.001) and had a lower body surface area (BSA) (1.55 ± 0.17m² vs.1.9 ± 0.2m², p < 0.001). Jockeys had a larger absolute left ventricular (LV) end diastolic volume (LVEDV) than the control group (120 ± 18.2 ml vs.109.3 ± 29.0 ml, p = 0.05) which had a larger variation when indexed for BSA (78.0 ± 12.2 ml/m² vs. 57.5 ± 13.3 ml/m², p < 0.001). Absolute LV mass did not differ between groups (123.8 ± 36.7g vs 124.2 ± 35.3g, p = 0.92), however jockeys demonstrated higher LV mass index (79.4 ± 18.1g/m² vs 65.2 ± 15.4g/m², p < 0.001). Both groups demonstrated clinically normal LV ejection fraction (LVEF) with jockeys being slightly higher, but not clinically different (60.8 ± 5.2% vs. 57 ± 3%, p < 0.001). Despite this, stroke volume (SV) was lower for jockeys than the control group (64.1 ± 12.6mL vs 75.7 ± 20.7mL), however, when indexed for BSA differences were not significant (p = 0.32). Left atrial volume index (LAVi) was larger in jockeys (33.4 ± 6.5mL/m² vs. 26.3 ± 7.0mL/m², p < 0.001). There were no differences in global longitudinal strain (GLS) (-19.3 ± 3.0 vs. -19.8 ± 1.6%, p = 0.52). Conclusions Jockeys have a distinct cardiac structure and function compared to the general population. Differences are attributed to chronic physiological demands of racing and should be considered in future research involving jockeys and by practitioners working with jockey athletes.