Preload maintenance protects against a depression in left ventricular systolic, but not diastolic, function immediately following ultraendurance exercise

Muhammad Yusuf Hassan ¹, Timothy D Noakes ¹, Peter Berlyn ¹, Robert E Shave ^2* and Keith George ³

¹ University of Cape Town and Sports Science Institute of South Africa, South Africa
² Brunel University, United Kingdom
³ Liverpool John Moores University, United Kingdom

^* To whom correspondence should be addressed. E-mail: rob.shave{at}brunel.ac.uk.

Accepted 20 February 2006

Abstract

Purpose: The purpose of this study was to investigate indices of left ventricular (LV) function before and after a 224-km Ironman Triathlon, specifically in the presence of unaltered haemodynamic loading. Method: Pre and post-race assessments of LV loading and function were obtained using M-mode and Doppler echocardiography in 39 (mean ± SD; age 33 ± 8 years, body mass 77.6 ± 8.6 kg, 36 males) triathletes in the Trendelenburg position. Specifically we assessed left ventricular end-diastolic volume (LVEDV) to estimate preload, systolic blood pressure (sBP) to estimate afterload as well as heart rate (HR). Systolic functional indices included ejection fraction (EF) and the end-systolic pressure/volume ratio (ESPV) and diastolic functional indices included peak mitral flow velocity in early (E) and atrial (A) filling as well as the ratio E/A. Pre and post-race data were compared via t-tests and delta LV functional indices were correlated with delta heart rate. Results: Preload (LVEDV: pre 143±34 vs. post 147±34 ml) and afterload (sBP: pre 115±20 vs. post 121±13 mmHg) were not significantly altered pre to post-race (P>0.05). EF (pre 61±8 vs. 58±10%) and ESPV (pre 2.4±0.9 vs. 2.1±0.8 mmHg.cm3) were not significantly altered post-race (P>0.05). The diastolic filling ratio E/A (pre 1.73± 0.25 vs. post 1.54± 0.23) was significantly reduced post-race (P<0.05) due primarily to a reduction in E. HR was significantly higher post-race (pre 57±9 vs. post 75±8 beats.min-1; P<0.05), but delta HR was not related to delta E/A (P>0.05). Conclusion: When preload and afterload are unaltered post-race, due to the adoption of a unique assessment posture, LV systolic function is not depressed. A depression in LV diastolic function persists that is not explained by an increase in heart rate post-race.

Key Words: Cardiac function, Prolonged exercise, Trendelenburg position, Triathlon

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