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

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Angela Farley, Hunter Bennett, Roger Eston, Rebecca Perry This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4240183/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 Nov, 2024 Read the published version in Sports Medicine-Open → Version 1 posted 5 You are reading this latest preprint version 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 ± 0.17m 2 vs.1.9 ± 0.2m 2 , 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/m 2 vs. 57.5 ± 13.3 ml/m 2 , 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/m 2 vs 65.2 ± 15.4g/m 2 , 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/m 2 vs. 26.3 ± 7.0mL/m 2 , 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. Thoroughbred horse racing jockey athlete’s heart echocardiography 3D echocardiography Figures Figure 1 Figure 2 Figure 3 1. Background Thoroughbred horse racing is one of the oldest and most lucrative sports in the world ( 1 ). Jockeys are at the forefront of this dynamic and at times perilous competition with their performance having a direct impact on race outcomes ( 2 ). In Australia, there are approximately 844 registered jockeys participating in over 19,000 races annually ( 3 ). The demands of this sport on jockey participants extend beyond mere athleticism, and also involve the constant pressure to perform exceptionally, with minimal rest between races ( 4 ). Jockeys also face significant challenges in maintaining weight to race, which can lead to nutritional deficiencies, dehydration, and associated health complications ( 5 ). Furthermore, the jockey occupation entails early mornings, long periods of travel to attend race meetings, and the rigours of ensuring race riding bodyweights of 52kgs to 61kgs are maintained ( 3 ). Jockeys will also often ride at race meetings on consecutive days, in multiple races at each meeting they attend, and without a stipulated ‘off-season’ ( 4 ). Therefore, the cardiovascular health of jockeys is an important area of investigation that requires closer examination. Ryan and Brodine (2021) conducted a comprehensive literature review of the physiological demands of racing and identified three studies that measured heart rate and mean oxygen uptake (VO 2 ) of jockeys during race conditions. It was demonstrated that jockeys experience elevated heart rates throughout each race (130–180 beats/min) with peak heart rates ranging from 150–190 beats/min ( 6 – 8 ). Substantial oxygen uptake was also demonstrated during races with oxygen uptake values ranging from 42.7 (± 5.6) to 57.5 (± 4.7) mlO 2 /kg/min ( 6 – 8 ). These findings confirm the rigorous physical nature of the sport and demonstrates cardiovascular demands similar to that of other elite athletes ( 6 – 8 ). Jockeys also adopt a distinctive crouched posture during races whereby quasi-isometric muscle activation occurs, indicating that jockeys require a unique blend of endurance and strength ( 9 ). Drawing from studies utilizing skin surface electromyography (EMG) and Training Impulse (TRIMP scores, (originally defined as the product of training volume, measured in minutes, and training intensity, normally measured as average heart rate) it is clear that jockeys experience exercise loads comparable to elite athletes in other sports ( 9 ). TRIMP scores are used to quantify the load or intensity of an athlete’s training over time and can be used as a comparative measure of exercise load ( 9 ). The TRIMP score for jockeys during 16 professional races was quantified at 292 ± 106 arbitrary units (au) ( 9 ). This is noteworthy considering the TRIMP experienced by a professional soccer player during a 1.5-hour match approximates ~ 190 au, whereas that of a world-class marathon runner participating in a 2-hour race reaches approximately 275 au ( 9 ). These findings highlight the athletic requirements of both endurance and strength in this demanding sport. It is well understood that cardiovascular physiological adaptations can occur due to the unique demands of regular and intense physical activity in the hearts of athletes ( 10 ). Common adaptations include enlargement of all four cardiac chambers, an increase in left ventricular (LV) wall thickness, and enhanced diastolic filling of the LV ( 11 ). The cardiovascular changes resulting from the physical demands of thoroughbred racing remain unexplored in this population of athletes. Beyond elite fitness requirements, jockeys face the additional challenge of maintaining a low body mass (50–61 kg) to meet race-related weight requirements ( 7 ). Often this is daily and, as there is no ‘off season’, many attempt to ‘cut weight’ all year-round ( 12 ). Unhealthy weight-loss techniques, including jogging in sweat gear, hot baths and saunas, coupled with nutritional deficiencies due to severe energy restriction and dehydration, are commonly used amongst jockey to maintain a chronically low body mass ( 6 ). There is evidence to suggest that these practices have detrimental effects on cardiac structure and function in the general population ( 13 ). These practices can lead to LV remodelling, left atrial (LA) enlargement, impaired myocardial contractility, altered diastolic function, reduced stroke volume, and decreased cardiac output ( 13 ). Additionally, changes in Global Longitudinal Strain (GLS) may indicate impaired myocardial performance ( 13 ). The combination of these adaptations can potentially increase the risk of cardiac dysfunction, arrhythmias, and other long-term cardiovascular complications ( 13 – 15 ). However, to the authors’ knowledge, this has yet to be investigated in jockeys. To examine the cardiac structure and function of jockeys, our study uses echocardiography, a sophisticated non-invasive imaging technique that employs high-frequency sound waves to create detailed images of structure and function of the heart ( 16 ). By capturing dynamic images of the heart's movements, this imaging modality allows for the identification of potential anomalies or adaptations in response to the unique physiological demands of exercise in jockeys ( 17 ). Therefore, the aims of this study were 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. 2. Material and Methods 2.1 Participant selection Professional Australian jockeys holding a current riding license in South Australia and Western Australia were invited to take part in the study. Data were collected from all jockeys on days of rest from race riding. Participants from the general population were invited using social media advertisements. Participants were excluded from the study if they were < 16 years of age or there was a previously undocumented heart abnormality discovered during the echocardiogram. All participants gave written informed consent, and the study was approved by the University of South Australia Human Research Ethics Committee (project number: 204235). 2.2 Anthropometric Measurements Immediately prior to their echocardiogram, anthropometric data were collected from all participants. Height was assessed to the nearest centimetre using a portable stadiometer (Seca 213, Hamburg, Germany). Body mass was measured in minimal light clothing using portable digital weighing scales (Tanita Innerscan, Body Composition Monitor, BC-541). Body Surface Area (BSA) was calculated according to the formula of Dubois and Dubois as a ratio of weight (kg) to height (m) ( 18 ). 2.3 Echocardiography Two-dimensional (2D) echocardiography included all standard views and measurements. These were taken in accordance with American Society of Echocardiography guidelines ( 17 ). All images were acquired using commercially available echocardiography systems (GE E95, Vivid IQ, General Electric, Horten, Norway). Advanced image analysis was performed using commercially available analysis software (TOMTEC Image Arena and Autostrain analysis, Unterschleissheim, Germany). As part of a standard echocardiogram, specific images for diastolic function including mitral valve inflow and tissue Doppler imaging (TDI) were taken. Left atrial volume (LAV) was measured from both the apical 4 and 2 chamber views with care to open the LA to its major axis. LV volumes and ejection fraction were measured using the Simpson’s rule of discs from the apical 4 and 2 chamber views where the major axis of the LV was found. Stoke volume was calculated from the LV outflow tract diameter and velocity time integral. LV GLS was calculated from LV focused images from the apical 4-chamber, 2-chamber, and long-axis views. Studies were deemed inadequate for GLS analysis if 2 or more LV segments could not be visualized. A region of interest was automatically applied by the software to the endocardial and epicardial borders, with tracking adjusted to cover the entire myocardium. GLS was calculated as the change in the length of line of the region of interest across all apical view from diastole to systole. All echocardiographic parameters were analysed by an expert (R.P.) to reduce variability. R.P. has published their reliability data as part of a previous study on echocardiography in athletes. Within this study, all echocardiographic parameters demonstrated excellent intra and inter-operator variability ( 11 ). 2.4 Statistical Analysis All statistical analyses were conducted using Statistical Package for the Social Sciences (SPSS) (v26, IBM, USA) with the level of statistical significance set at p < 0.05. Parametric data were presented as mean ± SD and nonparametric data as median (interquartile range) unless otherwise stated. A Mann-Witney U test to determine differences between the specific groups, jockeys, and general population, was used as the data were not normally distributed. Cohen’s effect size [ES] was calculated to determine differences between the two groups with the difference between the means divided by the pooled standard deviation calculated. Effect sizes were calculated (= z /sqrt(N)) and interpreted as follows: 0.79 = large ( 19 ). Furthermore, as BSA has been suggested to be flawed for indexing cardiac parameters in very small or large people ( 20 ), an exploratory analysis was conducted to identify whether any significant differences could be explained by differences in body size, whereby 19 variables were compared between the eight smallest participants in the control group and eight largest participants in the jockey groups using the above statistical methods. 3. Results Forty-six Australian jockeys and thirty-three participants from the general population (control group) consented to take part in this study. The results of the echocardiographic measurements and descriptive and mean anthropometric data for the jockey and control groups are presented in Table 1 and illustrated for comparison in Fig. 1 . There were no significant differences in age and gender between the jockeys and the control group. Jockeys were shorter (p < 0.001), weighed less (p < 0.001) and therefore had a lower BSA than the control group (p < 0.001). Even though their height, weight and BSA were less than the control group, jockeys had a larger LV end diastolic volume (LVEDV) (p = 0.05), which remained when indexed for BSA (p < 0.001). Absolute LV mass did not differ between the two groups (p = 0.92); however, the jockey group demonstrated a higher LV mass index than the control group (p < 0.001). Higher LV ejection fraction (LVEF) (p < 0.001), and a lower stroke volume (SV) (p = 0.021) were also demonstrated by the jockey group. However, when SV was indexed for BSA there was no longer a difference between the groups (p = 0.32). Figures 2A and 2B illustrate the LVEDV and LVEF findings demonstrated on echocardiography. Furthermore, LAV values were larger in jockeys, but only when indexed for BSA (p < 0.001). Despite the GLS being the same in both groups, there were 8 (17%) jockeys who had a GLS more impaired than − 16%, whereas all of the control group demonstrated normal GLS. The eight largest jockeys and eight smallest of the control group were also compared. There was no difference in BSA between the 2 groups (p = 0.28) suggesting that any cardiac changes observed are independent of body size. LVEDV, LVESV, LAV, LVEDV indexed for BSA, LV mass and LV mass index were all larger in jockeys compared to the control group (p < 0.05). Figures 3 A and 3 B illustrate a comparison of chamber sizes for each participant group demonstrated on echocardiography. Table 1 Descriptive data for controls vs jockeys Value Control (N = 33) Jockey (N = 46) U = p-Value Effect size Effect size descriptor Age (years) 36 ± 13 35 ± 12 697.50 0.54 0.07 Trivial Gender (males %) 17 (52%) 32 (70%) 622.0 0.11 0.19 Trivial Weight (kg) 74.2 ± 12.9 56.5 ± 6.0* 119.0 < 0.001 0.73 Moderate Height (m) 1.75 ± 0.09 1.64 ± 0.07* 252.5 < 0.001 0.58 Moderate BSA (m 2 ) 1.9 ± 0.2 1.55 ± 0.17* 118.0 < 0.001 0.73 Moderate GLS (%) -19.8 ± 1.6 (-17 to -23%) -19.3 ± 3.0 (-11 to -25%) 695.0 0.52 0.07 Trivial LVEDV (mL) 109.3 ± 29.0 120.0 ± 18.2 547.0 0.06 0.22 Small LVESV (mL) 47.4 ± 13.6 48.7 ± 12.1 710.5 0.8 0.03 Trivial LVEF (%) 57 ± 3 60.8 ± 5.2* 386.0 < 0.001 0.41 Small Mitral E:A ratio 1.9 ± 0.6 2.1 ± 0.9 654.5 0.415 0.09 Trivial E:E’ (avg) 5.6 ± 1.2 6.2 ± 1.5 556.0 0.09 0.19 Trivial Stroke Volume (mL) 75.7 ± 20.7 64.1 ± 12.6* 473.0 0.02 0.26 Small Stroke Volume index (mL/m 2 ) 39.8 ± 9.3 41.7 ± 8.2 601.0 0.32 0.11 Trivial HR (bpm) 60 ± 11 65 ± 13 577.5 0.23 0.14 Trivial Cardiac Output (L/min) 4.5 ± 1.4 4.1 ± 0.9 592.0 0.298 0.12 Trivial LA vol (biplane, mL) 49.7 ± 13.8 51.6 ± 10.7 593.5 0.341 0.11 Trivial LA vol index (mL/m 2 ) 26.3 ± 7.0 33.4 ± 6.5* 311.0 < 0.001 0.46 Small LVEDV index (mL/m 2 ) 57.5 ± 13.3 78.0 ± 12.2* 195.0 < 0.001 0.63 Moderate LV mass (g) 124.2 ± 35.3 123.8 ± 36.7 748.5 0.917 0.01 Trivial LV mass index (g/m 2 ) 64.2 ± 15.4 79.4 ± 18.1 429.0 < 0.001 0.34 Small *p < 0.05 compared with control group: BSA – body surface area, E:E’ – mitral inflow early diastolic velocity to tissue Doppler mitral annular early diastolic velocity ratio, GLS – global longitudinal strain, HR – heart rate, LA vol – left atrial volume, LV – left ventricular, LVEDV – left ventricular end diastolic volume, LVEF – left ventricular ejection fraction, LVESV – left ventricular end systolic volume. Values are presented as mean ± standard deviation or number and (percentage). 4. Discussion To the authors’ knowledge, this is the first study to evaluate the cardiac structure and function of jockey athletes with findings indicating that jockeys exhibit distinctive cardiac adaptations that are of considerable interest and may be comparable to other athlete groups. A critical finding is the presence of physiological remodelling of cardiac chambers in jockeys, particularly when indexed for BSA. Notably, jockeys exhibited larger LV and LA volumes as well as increased LV mass when indexed for BSA compared to the general population. It is also crucial to emphasize that these alterations in chamber dimensions were not associated with impaired cardiac function, whereby jockeys demonstrated normal LVEF ( 21 ). The observed increase in LV and LA volumes as well as LV mass, when indexed for BSA, could be attributed to the chronic physiological adaptations that occur in response to the intense and highly specialized physical regimens of jockeys ( 7 ). The preservation of normal LVEF, a critical indicator of cardiac systolic function, and stroke volume would suggest that despite the increased LA and LV volumes, the contractile capacity of their hearts was not compromised ( 22 ). It has also been well documented that an increase in these volumes occurs in athletes that train for both endurance and strength (such as rowers and cyclists), suggesting that jockeys sit within this demographic of sporting athletes ( 23 ) ( 24 ) ( 25 ). Also, given these findings, it is plausible to suggest that the more time spent in the sport the more likely adaptations in LVEF would occur, but this is something that should be examined in future research. Figures 2 (A and B) and 3 (A and B) illustrate these echocardiographic findings. Jockeys also had a lower absolute stroke volume; however, this was within normal limits and did not differ from the control group when indexed to BSA. Furthermore, jockeys had an increased left ventricular end-diastolic volume (LVEDV), although it was not statistically significant until it was indexed for BSA which indicates athletic adaptations have occurred ( 26 ). Jockeys exhibited significantly lower weight, height, and BSA compared to the control group. This may be attributed to the rigorous weight management requirements they face to meet racing standards, combined with the fact that jockeys’ are generally shorter on average than the general population ( 27 ). These factors could potentially influence cardiac parameters, leading to remodelling and adaptations in the jockeys' hearts ( 13 – 15 ). Also, whilst their LVEF was clinically normal and as a group, the GLS was normal, it is important to note that 17% of the jockeys in this study presented with reduced GLS, which is known to be a sensitive marker of myocardial deformation that can reveal subclinical changes in cardiac function such as LV dysfunction and hypertrophic myocardiopathy ( 11 ) ( 28 ). While our study was not designed to delve deeply into the specific causes of this, it may suggest that certain practices associated with Australian horse racing may lead to undesirable adaptations in cardiac function. One avenue for future investigation may centre on the effects of weight-shedding practices commonly employed by jockeys to meet the rigorous weight requirements of their profession. These practices, which include strategies such as saunas and extreme dietary restrictions, could conceivably exert detrimental effects on myocardial function, thus warranting further exploration in subsequent studies ( 15 ). 4.1 Limitations While the study's results are consistent with the hypothesis of cardiac remodelling in jockeys, it is important to acknowledge the limitations of the cross-sectional design. The sample sizes for both groups were relatively small, which may have affected the statistical power to detect significant differences in some parameters. This may limit the generalisability of these results to other jockey populations. However, the small jockey sample size can be attributed to the low number of jockeys that compete Australia wide, and therefore is a good representation of jockeys competing in Australia. Additionally, the cross-sectional design of the study limits the ability to draw causal relationships or determine the long-term effects of jockey training on cardiac health. Further research with larger sample sizes and longitudinal designs is warranted to validate and expand on these findings. 5. Conclusions This study investigated the cardiovascular structure and function of a group that has not previously been targeted. It provides valuable insights into the cardiovascular characteristics of registered Australian jockeys compared to the general population. The observed differences in LV and LA volumes and LV mass index highlight the potential cardiac adaptations that may occur in response to the unique physical demands required of jockeys. These findings underscore the importance of routine health assessment of jockeys to promote their cardiovascular health and well-being. They also highlight the need for further research on this specialised athlete population, especially against other elite athletes. The identification of a subset of jockeys with reduced GLS raises questions about the potential impact of weight shedding practices coupled with sustained intensive exercise, as an area ripe for future investigation. Abbreviations Electromyography EMG Training Impulse TRIMP Left ventricular LV Left atrial LA Global Longitudinal Strain GLS Body Surface Area BSA Two-dimensional 2D Tissue Doppler imaging TDI Left atrial volume LAV Statistical Package for the Social Sciences SPSS LV end diastolic volume LVEDV LV ejection fraction LVEF Stroke volume SV Mitral inflow early diastolic velocity to tissue Doppler mitral annular early diastolic velocity ratio E: E’ Heart rate HR Left ventricular end systolic volume LVESV Standard deviation SD Declarations Ethics Approval and Consent to Participate Informed written consent was obtained from all individual participants included in the study. The study was approved by the University of South Australia Human Research Ethics Committee (project number: 204235). Consent for publication All participants provided written consent for the use of their images in any publications produced as a result of their participation in this project. Data Availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Declaration of Interest/Competing Interests AF, HB, RE, and RP have no declarations of interest or conflicts of interest that are directly relevant to the content of this article and declare that they have no competing interests. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Author Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by AF and RP. The first draft of the manuscript was written by AF and all authors commented on and edited previous versions of the manuscript. All authors read and approved the final manuscript. 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Global longitudinal strain: clinical use and prognostic implications in contemporary practice. Heart. 2020;106(18):1438–44. Cite Share Download PDF Status: Published Journal Publication published 05 Nov, 2024 Read the published version in Sports Medicine-Open → Version 1 posted Editor invited by journal 07 May, 2024 Reviewers agreed at journal 18 Apr, 2024 Reviewers invited by journal 17 Apr, 2024 Editor assigned by journal 09 Apr, 2024 First submitted to journal 09 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4240183","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":292564035,"identity":"2831d589-dc96-45a5-b8fd-5f8d01428ff5","order_by":0,"name":"Angela Farley","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-0743-1615","institution":"University of South Australia - City East Campus","correspondingAuthor":true,"prefix":"","firstName":"Angela","middleName":"","lastName":"Farley","suffix":""},{"id":292564036,"identity":"00b86f52-32f9-488d-a901-99414e22238b","order_by":1,"name":"Hunter Bennett","email":"","orcid":"","institution":"University of South Australia","correspondingAuthor":false,"prefix":"","firstName":"Hunter","middleName":"","lastName":"Bennett","suffix":""},{"id":292564037,"identity":"2e4da0eb-0405-492b-a9f6-2d0bd3430366","order_by":2,"name":"Roger Eston","email":"","orcid":"","institution":"University of South Australia","correspondingAuthor":false,"prefix":"","firstName":"Roger","middleName":"","lastName":"Eston","suffix":""},{"id":292564038,"identity":"8ccad1af-0a77-4abc-b72a-8983e89af5e0","order_by":3,"name":"Rebecca Perry","email":"","orcid":"","institution":"University of South Australia","correspondingAuthor":false,"prefix":"","firstName":"Rebecca","middleName":"","lastName":"Perry","suffix":""}],"badges":[],"createdAt":"2024-04-09 06:58:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4240183/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4240183/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s40798-024-00783-9","type":"published","date":"2024-11-05T15:57:35+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":55510465,"identity":"5c08e255-40da-4264-b485-8656feed4029","added_by":"auto","created_at":"2024-04-29 12:29:08","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":238513,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of significant findings for nonathletic participants vs jockey participants\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eComparison of nonathletic participant (Black) to jockey (white) significant findings. Figure legend: LVEDV = Left ventricular end diastolic volume, LV = Left ventricular, ns = not significant, * = p\u0026lt;0.001.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Centralillustration.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4240183/v1/6e7a4090fa74ec3ab4837a67.jpg"},{"id":55510466,"identity":"3a0171de-837d-49d0-a8cc-873829c48313","added_by":"auto","created_at":"2024-04-29 12:29:08","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":362892,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e2A \u0026amp; 2B:\u003c/em\u003e \u003cem\u003eLeft ventricular volume and ejection fraction measurements from a control, non-athletic participant (A) demonstrating a left ventricular end diastolic volume of 79mL and ejection fraction of 58% and in a jockey (B) demonstrating a larger left ventricular end diastolic volume of 116mL and lower ejection fraction of 49%.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"ControlLVvolume1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4240183/v1/b11d56567a17190be87276b4.jpg"},{"id":55510471,"identity":"89114e48-77e5-44d5-9355-9fcf8c46804d","added_by":"auto","created_at":"2024-04-29 12:29:10","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":199405,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e3A and 3B: Apical 4-chamber views from a control, non-athletic participant (A) and jockey (B). Note that all 4 chambers of the heart are larger in the jockey.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Control4ch.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4240183/v1/2f2a871648b3420ddcb06c14.jpg"},{"id":68749931,"identity":"047ba0b1-11c8-4277-b350-0ad5b1cc5229","added_by":"auto","created_at":"2024-11-11 16:07:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1264311,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4240183/v1/d3a769fd-3bcb-4447-8b7f-044995e57ae1.pdf"}],"financialInterests":"","formattedTitle":"Cardiac structure and function of elite Australian jockeys differs to the general population: An observational cross-sectional study.","fulltext":[{"header":"1. Background","content":"\u003cp\u003eThoroughbred horse racing is one of the oldest and most lucrative sports in the world (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Jockeys are at the forefront of this dynamic and at times perilous competition with their performance having a direct impact on race outcomes (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). In Australia, there are approximately 844 registered jockeys participating in over 19,000 races annually (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). The demands of this sport on jockey participants extend beyond mere athleticism, and also involve the constant pressure to perform exceptionally, with minimal rest between races (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Jockeys also face significant challenges in maintaining weight to race, which can lead to nutritional deficiencies, dehydration, and associated health complications (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Furthermore, the jockey occupation entails early mornings, long periods of travel to attend race meetings, and the rigours of ensuring race riding bodyweights of 52kgs to 61kgs are maintained (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Jockeys will also often ride at race meetings on consecutive days, in multiple races at each meeting they attend, and without a stipulated \u0026lsquo;off-season\u0026rsquo; (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Therefore, the cardiovascular health of jockeys is an important area of investigation that requires closer examination.\u003c/p\u003e \u003cp\u003eRyan and Brodine (2021) conducted a comprehensive literature review of the physiological demands of racing and identified three studies that measured heart rate and mean oxygen uptake (VO\u003csub\u003e2\u003c/sub\u003e) of jockeys during race conditions. It was demonstrated that jockeys experience elevated heart rates throughout each race (130\u0026ndash;180 beats/min) with peak heart rates ranging from 150\u0026ndash;190 beats/min (\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Substantial oxygen uptake was also demonstrated during races with oxygen uptake values ranging from 42.7 (\u0026plusmn;\u0026thinsp;5.6) to 57.5 (\u0026plusmn;\u0026thinsp;4.7) mlO\u003csub\u003e2\u003c/sub\u003e/kg/min (\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). These findings confirm the rigorous physical nature of the sport and demonstrates cardiovascular demands similar to that of other elite athletes (\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Jockeys also adopt a distinctive crouched posture during races whereby quasi-isometric muscle activation occurs, indicating that jockeys require a unique blend of endurance and strength (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDrawing from studies utilizing skin surface electromyography (EMG) and Training Impulse (TRIMP scores, (originally defined as the product of training volume, measured in minutes, and training intensity, normally measured as average heart rate) it is clear that jockeys experience exercise loads comparable to elite athletes in other sports (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). TRIMP scores are used to quantify the load or intensity of an athlete\u0026rsquo;s training over time and can be used as a comparative measure of exercise load (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). The TRIMP score for jockeys during 16 professional races was quantified at 292\u0026thinsp;\u0026plusmn;\u0026thinsp;106 arbitrary units (au) (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). This is noteworthy considering the TRIMP experienced by a professional soccer player during a 1.5-hour match approximates\u0026thinsp;~\u0026thinsp;190 au, whereas that of a world-class marathon runner participating in a 2-hour race reaches approximately 275 au (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). These findings highlight the athletic requirements of both endurance and strength in this demanding sport.\u003c/p\u003e \u003cp\u003eIt is well understood that cardiovascular physiological adaptations can occur due to the unique demands of regular and intense physical activity in the hearts of athletes (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Common adaptations include enlargement of all four cardiac chambers, an increase in left ventricular (LV) wall thickness, and enhanced diastolic filling of the LV (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). The cardiovascular changes resulting from the physical demands of thoroughbred racing remain unexplored in this population of athletes.\u003c/p\u003e \u003cp\u003eBeyond elite fitness requirements, jockeys face the additional challenge of maintaining a low body mass (50\u0026ndash;61 kg) to meet race-related weight requirements (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Often this is daily and, as there is no \u0026lsquo;off season\u0026rsquo;, many attempt to \u0026lsquo;cut weight\u0026rsquo; all year-round (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Unhealthy weight-loss techniques, including jogging in sweat gear, hot baths and saunas, coupled with nutritional deficiencies due to severe energy restriction and dehydration, are commonly used amongst jockey to maintain a chronically low body mass (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). There is evidence to suggest that these practices have detrimental effects on cardiac structure and function in the general population (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). These practices can lead to LV remodelling, left atrial (LA) enlargement, impaired myocardial contractility, altered diastolic function, reduced stroke volume, and decreased cardiac output (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Additionally, changes in Global Longitudinal Strain (GLS) may indicate impaired myocardial performance (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). The combination of these adaptations can potentially increase the risk of cardiac dysfunction, arrhythmias, and other long-term cardiovascular complications (\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). However, to the authors\u0026rsquo; knowledge, this has yet to be investigated in jockeys.\u003c/p\u003e \u003cp\u003eTo examine the cardiac structure and function of jockeys, our study uses echocardiography, a sophisticated non-invasive imaging technique that employs high-frequency sound waves to create detailed images of structure and function of the heart (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). By capturing dynamic images of the heart's movements, this imaging modality allows for the identification of potential anomalies or adaptations in response to the unique physiological demands of exercise in jockeys (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Therefore, the aims of this study were 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.\u003c/p\u003e"},{"header":"2. Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Participant selection\u003c/h2\u003e \u003cp\u003eProfessional Australian jockeys holding a current riding license in South Australia and Western Australia were invited to take part in the study. Data were collected from all jockeys on days of rest from race riding. Participants from the general population were invited using social media advertisements. Participants were excluded from the study if they were \u0026lt;\u0026thinsp;16 years of age or there was a previously undocumented heart abnormality discovered during the echocardiogram. All participants gave written informed consent, and the study was approved by the University of South Australia Human Research Ethics Committee (project number: 204235).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Anthropometric Measurements\u003c/h2\u003e \u003cp\u003eImmediately prior to their echocardiogram, anthropometric data were collected from all participants. Height was assessed to the nearest centimetre using a portable stadiometer (Seca 213, Hamburg, Germany). Body mass was measured in minimal light clothing using portable digital weighing scales (Tanita Innerscan, Body Composition Monitor, BC-541). Body Surface Area (BSA) was calculated according to the formula of Dubois and Dubois as a ratio of weight (kg) to height (m) (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Echocardiography\u003c/h2\u003e \u003cp\u003eTwo-dimensional (2D) echocardiography included all standard views and measurements. These were taken in accordance with American Society of Echocardiography guidelines (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). All images were acquired using commercially available echocardiography systems (GE E95, Vivid IQ, General Electric, Horten, Norway). Advanced image analysis was performed using commercially available analysis software (TOMTEC Image Arena and Autostrain analysis, Unterschleissheim, Germany). As part of a standard echocardiogram, specific images for diastolic function including mitral valve inflow and tissue Doppler imaging (TDI) were taken. Left atrial volume (LAV) was measured from both the apical 4 and 2 chamber views with care to open the LA to its major axis. LV volumes and ejection fraction were measured using the Simpson\u0026rsquo;s rule of discs from the apical 4 and 2 chamber views where the major axis of the LV was found. Stoke volume was calculated from the LV outflow tract diameter and velocity time integral. LV GLS was calculated from LV focused images from the apical 4-chamber, 2-chamber, and long-axis views. Studies were deemed inadequate for GLS analysis if 2 or more LV segments could not be visualized. A region of interest was automatically applied by the software to the endocardial and epicardial borders, with tracking adjusted to cover the entire myocardium. GLS was calculated as the change in the length of line of the region of interest across all apical view from diastole to systole. All echocardiographic parameters were analysed by an expert (R.P.) to reduce variability. R.P. has published their reliability data as part of a previous study on echocardiography in athletes. Within this study, all echocardiographic parameters demonstrated excellent intra and inter-operator variability (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Statistical Analysis\u003c/h2\u003e \u003cp\u003eAll statistical analyses were conducted using Statistical Package for the Social Sciences (SPSS) (v26, IBM, USA) with the level of statistical significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05. Parametric data were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD and nonparametric data as median (interquartile range) unless otherwise stated. A Mann-Witney U test to determine differences between the specific groups, jockeys, and general population, was used as the data were not normally distributed. Cohen\u0026rsquo;s effect size [ES] was calculated to determine differences between the two groups with the difference between the means divided by the pooled standard deviation calculated. Effect sizes were calculated (=\u0026thinsp;z /sqrt(N)) and interpreted as follows: \u0026lt;0.20\u0026thinsp;=\u0026thinsp;\u003cem\u003etrivial\u003c/em\u003e, 0.20\u0026ndash;0.49\u0026thinsp;=\u0026thinsp;\u003cem\u003esmall\u003c/em\u003e, 0.50\u0026ndash;0.79\u0026thinsp;=\u0026thinsp;\u003cem\u003emoderate\u003c/em\u003e, and \u0026gt;\u0026thinsp;0.79\u0026thinsp;=\u0026thinsp;\u003cem\u003elarge\u003c/em\u003e (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, as BSA has been suggested to be flawed for indexing cardiac parameters in very small or large people (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e), an exploratory analysis was conducted to identify whether any significant differences could be explained by differences in body size, whereby 19 variables were compared between the eight smallest participants in the control group and eight largest participants in the jockey groups using the above statistical methods.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003eForty-six Australian jockeys and thirty-three participants from the general population (control group) consented to take part in this study. The results of the echocardiographic measurements and descriptive and mean anthropometric data for the jockey and control groups are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and illustrated for comparison in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were no significant differences in age and gender between the jockeys and the control group. Jockeys were shorter (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), weighed less (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and therefore had a lower BSA than the control group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Even though their height, weight and BSA were less than the control group, jockeys had a larger LV end diastolic volume (LVEDV) (p\u0026thinsp;=\u0026thinsp;0.05), which remained when indexed for BSA (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Absolute LV mass did not differ between the two groups (p\u0026thinsp;=\u0026thinsp;0.92); however, the jockey group demonstrated a higher LV mass index than the control group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Higher LV ejection fraction (LVEF) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and a lower stroke volume (SV) (p\u0026thinsp;=\u0026thinsp;0.021) were also demonstrated by the jockey group. However, when SV was indexed for BSA there was no longer a difference between the groups (p\u0026thinsp;=\u0026thinsp;0.32).\u003c/p\u003e \u003cp\u003eFigures 2A and 2B illustrate the LVEDV and LVEF findings demonstrated on echocardiography.\u003c/p\u003e \u003cp\u003eFurthermore, LAV values were larger in jockeys, but only when indexed for BSA (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Despite the GLS being the same in both groups, there were 8 (17%) jockeys who had a GLS more impaired than \u0026minus;\u0026thinsp;16%, whereas all of the control group demonstrated normal GLS.\u003c/p\u003e \u003cp\u003eThe eight largest jockeys and eight smallest of the control group were also compared. There was no difference in BSA between the 2 groups (p\u0026thinsp;=\u0026thinsp;0.28) suggesting that any cardiac changes observed are independent of body size. LVEDV, LVESV, LAV, LVEDV indexed for BSA, LV mass and LV mass index were all larger in jockeys compared to the control group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eA and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eB illustrate a comparison of chamber sizes for each participant group demonstrated on echocardiography.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDescriptive data for controls vs jockeys\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eControl (N\u0026thinsp;=\u0026thinsp;33)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eJockey (N\u0026thinsp;=\u0026thinsp;46)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eU =\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep-Value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eEffect size\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eEffect size descriptor\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36\u0026thinsp;\u0026plusmn;\u0026thinsp;13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35\u0026thinsp;\u0026plusmn;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e697.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender (males %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17 (52%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32 (70%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e622.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74.2\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e119.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eModerate\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e252.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eModerate\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBSA (m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e118.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eModerate\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGLS (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-19.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6 (-17 to -23%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-19.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0 (-11 to -25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e695.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVEDV (mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e109.3\u0026thinsp;\u0026plusmn;\u0026thinsp;29.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120.0\u0026thinsp;\u0026plusmn;\u0026thinsp;18.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e547.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eSmall\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVESV (mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e47.4\u0026thinsp;\u0026plusmn;\u0026thinsp;13.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.7\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e710.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVEF (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e386.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eSmall\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMitral E:A ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e654.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.415\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eE:E\u0026rsquo; (avg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e556.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStroke Volume (mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75.7\u0026thinsp;\u0026plusmn;\u0026thinsp;20.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e473.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.02\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eSmall\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStroke Volume index (mL/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e601.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHR (bpm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60\u0026thinsp;\u0026plusmn;\u0026thinsp;11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e65\u0026thinsp;\u0026plusmn;\u0026thinsp;13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e577.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCardiac Output (L/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e592.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.298\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLA vol (biplane, mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49.7\u0026thinsp;\u0026plusmn;\u0026thinsp;13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51.6\u0026thinsp;\u0026plusmn;\u0026thinsp;10.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e593.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.341\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLA vol index (mL/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e311.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eSmall\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVEDV index (mL/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e78.0\u0026thinsp;\u0026plusmn;\u0026thinsp;12.2*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e195.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eModerate\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLV mass (g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e124.2\u0026thinsp;\u0026plusmn;\u0026thinsp;35.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e123.8\u0026thinsp;\u0026plusmn;\u0026thinsp;36.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e748.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.917\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eTrivial\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLV mass index (g/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64.2\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e79.4\u0026thinsp;\u0026plusmn;\u0026thinsp;18.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e429.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eSmall\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003e*p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 compared with control group: BSA \u0026ndash; body surface area, E:E\u0026rsquo; \u0026ndash; mitral inflow early diastolic velocity to tissue Doppler mitral annular early diastolic velocity ratio, GLS \u0026ndash; global longitudinal strain, HR \u0026ndash; heart rate, LA vol \u0026ndash; left atrial volume, LV \u0026ndash; left ventricular, LVEDV \u0026ndash; left ventricular end diastolic volume, LVEF \u0026ndash; left ventricular ejection fraction, LVESV \u0026ndash; left ventricular end systolic volume. Values are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or number and (percentage).\u003c/em\u003e \u003c/p\u003e "},{"header":"4. Discussion","content":"\u003cp\u003eTo the authors\u0026rsquo; knowledge, this is the first study to evaluate the cardiac structure and function of jockey athletes with findings indicating that jockeys exhibit distinctive cardiac adaptations that are of considerable interest and may be comparable to other athlete groups. A critical finding is the presence of physiological remodelling of cardiac chambers in jockeys, particularly when indexed for BSA. Notably, jockeys exhibited larger LV and LA volumes as well as increased LV mass when indexed for BSA compared to the general population.\u003c/p\u003e \u003cp\u003eIt is also crucial to emphasize that these alterations in chamber dimensions were not associated with impaired cardiac function, whereby jockeys demonstrated normal LVEF (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). The observed increase in LV and LA volumes as well as LV mass, when indexed for BSA, could be attributed to the chronic physiological adaptations that occur in response to the intense and highly specialized physical regimens of jockeys (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The preservation of normal LVEF, a critical indicator of cardiac systolic function, and stroke volume would suggest that despite the increased LA and LV volumes, the contractile capacity of their hearts was not compromised (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). It has also been well documented that an increase in these volumes occurs in athletes that train for both endurance and strength (such as rowers and cyclists), suggesting that jockeys sit within this demographic of sporting athletes (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e) (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e) (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). Also, given these findings, it is plausible to suggest that the more time spent in the sport the more likely adaptations in LVEF would occur, but this is something that should be examined in future research. Figures\u0026nbsp;2 (A and B) and 3 (A and B) illustrate these echocardiographic findings.\u003c/p\u003e \u003cp\u003eJockeys also had a lower absolute stroke volume; however, this was within normal limits and did not differ from the control group when indexed to BSA. Furthermore, jockeys had an increased left ventricular end-diastolic volume (LVEDV), although it was not statistically significant until it was indexed for BSA which indicates athletic adaptations have occurred (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). Jockeys exhibited significantly lower weight, height, and BSA compared to the control group. This may be attributed to the rigorous weight management requirements they face to meet racing standards, combined with the fact that jockeys\u0026rsquo; are generally shorter on average than the general population (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). These factors could potentially influence cardiac parameters, leading to remodelling and adaptations in the jockeys' hearts (\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Also, whilst their LVEF was clinically normal and as a group, the GLS was normal, it is important to note that 17% of the jockeys in this study presented with reduced GLS, which is known to be a sensitive marker of myocardial deformation that can reveal subclinical changes in cardiac function such as LV dysfunction and hypertrophic myocardiopathy (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). While our study was not designed to delve deeply into the specific causes of this, it may suggest that certain practices associated with Australian horse racing may lead to undesirable adaptations in cardiac function. One avenue for future investigation may centre on the effects of weight-shedding practices commonly employed by jockeys to meet the rigorous weight requirements of their profession. These practices, which include strategies such as saunas and extreme dietary restrictions, could conceivably exert detrimental effects on myocardial function, thus warranting further exploration in subsequent studies (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Limitations\u003c/h2\u003e \u003cp\u003eWhile the study's results are consistent with the hypothesis of cardiac remodelling in jockeys, it is important to acknowledge the limitations of the cross-sectional design. The sample sizes for both groups were relatively small, which may have affected the statistical power to detect significant differences in some parameters. This may limit the generalisability of these results to other jockey populations. However, the small jockey sample size can be attributed to the low number of jockeys that compete Australia wide, and therefore is a good representation of jockeys competing in Australia. Additionally, the cross-sectional design of the study limits the ability to draw causal relationships or determine the long-term effects of jockey training on cardiac health. Further research with larger sample sizes and longitudinal designs is warranted to validate and expand on these findings.\u003c/p\u003e \u003c/div\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eThis study investigated the cardiovascular structure and function of a group that has not previously been targeted. It provides valuable insights into the cardiovascular characteristics of registered Australian jockeys compared to the general population. The observed differences in LV and LA volumes and LV mass index highlight the potential cardiac adaptations that may occur in response to the unique physical demands required of jockeys. These findings underscore the importance of routine health assessment of jockeys to promote their cardiovascular health and well-being. They also highlight the need for further research on this specialised athlete population, especially against other elite athletes. The identification of a subset of jockeys with reduced GLS raises questions about the potential impact of weight shedding practices coupled with sustained intensive exercise, as an area ripe for future investigation.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eElectromyography\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;EMG\u003c/p\u003e\n\u003cp\u003eTraining Impulse\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;TRIMP\u003c/p\u003e\n\u003cp\u003eLeft ventricular\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;LV\u003c/p\u003e\n\u003cp\u003eLeft atrial\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;LA\u003c/p\u003e\n\u003cp\u003eGlobal Longitudinal Strain\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;GLS\u003c/p\u003e\n\u003cp\u003eBody Surface Area\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;BSA\u003c/p\u003e\n\u003cp\u003eTwo-dimensional \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;2D\u003c/p\u003e\n\u003cp\u003eTissue Doppler imaging\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;TDI\u003c/p\u003e\n\u003cp\u003eLeft atrial volume\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;LAV\u003c/p\u003e\n\u003cp\u003eStatistical Package for the Social Sciences\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;SPSS\u003c/p\u003e\n\u003cp\u003eLV end diastolic volume\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;LVEDV\u003c/p\u003e\n\u003cp\u003eLV ejection fraction\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;LVEF\u003c/p\u003e\n\u003cp\u003eStroke volume\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;SV\u003c/p\u003e\n\u003cp\u003eMitral inflow early diastolic velocity to tissue Doppler mitral annular early diastolic velocity ratio \u0026nbsp; \u0026nbsp; \u0026nbsp;E: E\u0026rsquo;\u003c/p\u003e\n\u003cp\u003eHeart rate\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;HR\u003c/p\u003e\n\u003cp\u003eLeft ventricular end systolic volume\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;LVESV\u003c/p\u003e\n\u003cp\u003eStandard deviation \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;SD\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cu\u003eEthics Approval and Consent to Participate\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eInformed written consent was obtained from all individual participants included in the study. The study was approved by the\u0026nbsp;University of South Australia\u0026nbsp;Human Research Ethics Committee (project number: 204235).\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eConsent for publication\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eAll participants provided written consent for the use of their images in any publications produced as a result of their participation in this project.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eData Availability\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eDeclaration of\u003c/u\u003e\u003cu\u003e\u0026nbsp;Interest/Competing Interests\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eAF, HB, RE, and RP have no declarations of interest or conflicts of interest that are directly relevant to the content of this article and declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eFunding\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAuthor Contributions\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by AF and RP. The first draft of the manuscript was written by AF and all authors commented on and edited previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAcknowledgements\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe authors wish to acknowledge the Australian Jockeys\u0026rsquo; Association, Racing South Australia and Racing and Wagering Western Australia for their support throughout this project. The authors would also like to thank GE Healthcare Australia for assistance with equipment and software.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDavies M, Jackson KA, Mackinnon AL, Turner A, Kuznik K, Hill J, et al. Epidemiology of race day injury in young professional jockeys in Great Britain from 2007 to 2018: a retrospective cohort study. 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Dehydration reduces left ventricular filling at rest and during exercise independent of twist mechanics. J Appl Physiol (1985). 2011;111(3):891\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWatanabe K, St\u0026ouml;hr EJ, Akiyama K, Watanabe S, Gonz\u0026aacute;lez-Alonso J. Dehydration reduces stroke volume and cardiac output during exercise because of impaired cardiac filling and venous return, not left ventricular function. Physiol Rep. 2020;8(11):e14433. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e-n/a\u003c/span\u003e\u003cspan address=\"http://-n/a\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLowry MTH, Gibson PH. Echocardiography. Medicine (Abingdon 1995, UK ed). 2022;50(6):357\u0026thinsp;\u0026ndash;\u0026thinsp;62.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2015;16(3):233\u0026ndash;71.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVerbraecken J, Van de Heyning P, De Backer W, Van Gaal L. Body surface area in normal-weight, overweight, and obese adults. A comparison study. Metab Clin Exp. 2006;55(4):515\u0026ndash;24.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCohen J. Statistical power analysis for the behavioral sciences. 2nd ed. ed. Hillsdale, N.J: L. Erlbaum Associates; 1988.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDewey FE, Rosenthal D, Murphy DJ, Froelicher VF, Ashley EA. Does Size Matter? Clinical Applications of Scaling Cardiac Size and Function for Body Size. Circulation. 2008;117(17):2279\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYılmaz M, Kayan\u0026ccedil;i\u0026ccedil;ek H, Elevated LV, Mass. LV Mass Index Sign on the Athlete's ECG: Athletes' Hearts are Prone to Ventricular Arrhythmia. J Clin Med. 2018;7(6):122.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuchynka P, Palecek T, Vilikus Z, Havranek S, Taborska K, Louch WE, et al. Cardiac Structural and Functional Changes in Competitive Amateur Cyclists. Echocardiography (Mount Kisco NY). 2010;27(1):11\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePluim BM, Zwinderman AH, Van Der Laarse A, Van Der Wall EE. The athlete's heart: A meta-analysis of cardiac structure and function. Volume 101. New York, NY): Circulation; 2000. pp. 336\u0026ndash;44. 3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKovacs RMD, Baggish ALMD. Cardiovascular adaptation in athletes. Trends Cardiovasc Med. 2016;26(1):46\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCheng S, Xanthakis V, Sullivan LM, Lieb W, Massaro J, Aragam J, et al. Correlates of Echocardiographic Indices of Cardiac Remodeling Over the Adult Life Course: Longitudinal Observations From the Framingham Heart Study. Circulation. 2010;122(6):570\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePelliccia A, Caselli S, Sharma S, Basso C, Bax JJ, Corrado D, et al. European Association of Preventive Cardiology (EAPC) and European Association of Cardiovascular Imaging (EACVI) joint position statement: recommendations for the indication and interpretation of cardiovascular imaging in the evaluation of the athlete's heart. Eur Heart J. 2018;39(21):1949\u0026ndash;.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWilson G, Drust B, Morton JP, Close GL. Weight-Making Strategies in Professional Jockeys: Implications for Physical and Mental Health and Well-Being. Sports Med. 2014;44(6):785\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbou R, van der Bijl P, Bax JJ, Delgado V. Global longitudinal strain: clinical use and prognostic implications in contemporary practice. Heart. 2020;106(18):1438\u0026ndash;44.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"sports-medicine-open","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"smoa","sideBox":"Learn more about [Sports Medicine-Open](http://sportsmedicine-open.springeropen.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/smoa/default.aspx","title":"Sports Medicine-Open","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Thoroughbred horse racing, jockey, athlete’s heart, echocardiography, 3D echocardiography","lastPublishedDoi":"10.21203/rs.3.rs-4240183/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4240183/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe 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.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eForty-six Australian jockeys (35\u0026thinsp;\u0026plusmn;\u0026thinsp;12 years) and thirty-three age- and gender-matched (36\u0026thinsp;\u0026plusmn;\u0026thinsp;13 years) participants from the general population participated in this study. Jockeys were shorter (1.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07 vs. 1.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09m, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), lighter (56.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0 vs. 74.2\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9kg, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and had a lower body surface area (BSA) (1.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17m\u003csup\u003e2\u003c/sup\u003e vs.1.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2m\u003csup\u003e2\u003c/sup\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Jockeys had a larger absolute left ventricular (LV) end diastolic volume (LVEDV) than the control group (120\u0026thinsp;\u0026plusmn;\u0026thinsp;18.2 ml vs.109.3\u0026thinsp;\u0026plusmn;\u0026thinsp;29.0 ml, p\u0026thinsp;=\u0026thinsp;0.05) which had a larger variation when indexed for BSA (78.0\u0026thinsp;\u0026plusmn;\u0026thinsp;12.2 ml/m\u003csup\u003e2\u003c/sup\u003e vs. 57.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.3 ml/m\u003csup\u003e2\u003c/sup\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Absolute LV mass did not differ between groups (123.8\u0026thinsp;\u0026plusmn;\u0026thinsp;36.7g vs 124.2\u0026thinsp;\u0026plusmn;\u0026thinsp;35.3g, p\u0026thinsp;=\u0026thinsp;0.92), however jockeys demonstrated higher LV mass index (79.4\u0026thinsp;\u0026plusmn;\u0026thinsp;18.1g/m\u003csup\u003e2\u003c/sup\u003e vs 65.2\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4g/m\u003csup\u003e2\u003c/sup\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Both groups demonstrated clinically normal LV ejection fraction (LVEF) with jockeys being slightly higher, but not clinically different (60.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2% vs. 57\u0026thinsp;\u0026plusmn;\u0026thinsp;3%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Despite this, stroke volume (SV) was lower for jockeys than the control group (64.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6mL vs 75.7\u0026thinsp;\u0026plusmn;\u0026thinsp;20.7mL), however, when indexed for BSA differences were not significant (p\u0026thinsp;=\u0026thinsp;0.32). Left atrial volume index (LAVi) was larger in jockeys (33.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5mL/m\u003csup\u003e2\u003c/sup\u003e vs. 26.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.0mL/m\u003csup\u003e2\u003c/sup\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). There were no differences in global longitudinal strain (GLS) (-19.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0 vs. -19.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6%, p\u0026thinsp;=\u0026thinsp;0.52).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eJockeys 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.\u003c/p\u003e","manuscriptTitle":"Cardiac structure and function of elite Australian jockeys differs to the general population: An observational cross-sectional study.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-29 12:28:29","doi":"10.21203/rs.3.rs-4240183/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvited","content":"Sports Medicine-Open","date":"2024-05-08T00:34:40+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-04-18T19:21:19+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-18T02:55:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-09T12:21:13+00:00","index":"","fulltext":""},{"type":"submitted","content":"Sports Medicine-Open","date":"2024-04-09T07:35:00+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"sports-medicine-open","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"smoa","sideBox":"Learn more about [Sports Medicine-Open](http://sportsmedicine-open.springeropen.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/smoa/default.aspx","title":"Sports Medicine-Open","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c0fe74b6-e7ce-4854-9030-c02b0f6ffd28","owner":[],"postedDate":"April 29th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-11-11T16:01:27+00:00","versionOfRecord":{"articleIdentity":"rs-4240183","link":"https://doi.org/10.1186/s40798-024-00783-9","journal":{"identity":"sports-medicine-open","isVorOnly":false,"title":"Sports Medicine-Open"},"publishedOn":"2024-11-05 15:57:35","publishedOnDateReadable":"November 5th, 2024"},"versionCreatedAt":"2024-04-29 12:28:29","video":"","vorDoi":"10.1186/s40798-024-00783-9","vorDoiUrl":"https://doi.org/10.1186/s40798-024-00783-9","workflowStages":[]},"version":"v1","identity":"rs-4240183","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4240183","identity":"rs-4240183","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}