INTRODUCTION: Due to high cardiac workload, prolonged intense exercise results in an exercise-induced cardiac fatigue (EICF) (1). This phenomenon is characterized by transient cardiac function alterations associated to an increase in the cardiac damage biomarkers after athletes performed this type of sport events whether isolated or repeated over several days (2). The EICF is generally assessed by conventional echocardiography and/or cardiac biomarkers, but these tools are expensive and require highly qualified bio-medical staff. The cardiovascular control by autonomous nervous system (ANS) can be assessed by heart rate variability (HRV) analysis. Due to strong relationship between ANS, HRV and cardiac function, we can consider the interest of the HRV analysis for determined EICF. The objective of the study was to describe the evolution of cardiac function and HRV parameters during a multi-stage cycling event and to determine their relationship. METHODS: Using a case study approach, this investigation focused on one female athlete who performed the 21 stages of the Tour de France circuit 2018 without any spirit of competition of performance goal. Each morning, she underwent a rest transthoracic echocardiography and a RR recording (5 minutes supine, 5 minutes standing). Cardiac function was assessed by conventional echocardiography, tissue Doppler imaging and speckle tracking techniques. HRV analysis was performed in time and frequency domains. Descriptive analysis of cardiac function and HRV was first performed. Then, correlations between cardiac function and HRV parameters were tested (p<0,05, r=0,8). RESULTS: Multiple`s variations were observed on both diastolic and systolic function parameters (E/A, E/E` mean, LV global longitudinal strain, LVEF, S` mean) of left ventricle. There were also variations on the systolic function parameters of the right ventricle (TAPSE, FAC, RV longitudinal strain). These variations were not considered as alterations or degradations of the heart function also known as EICF. During the 21 stages, multiple`s variations were observed for the HRV parameters such as imbalance of HRV, increase of sympathetic tone and decrease of parasympathetic tone. No significant correlation was found between the HRV and the echocardiophy parameters. CONCLUSION: Despite HRV imbalance, no evidence of a cardiac fatigue was observed all along the event. This repeated and prolonged endurance exercise seems insufficiently stressful to impair cardiac function, perhaps due to too moderate intensity.
© Copyright 2022 27th Annual Congress of the European College of Sport Science (ECSS), Sevilla, 30. Aug - 2. Sep 2022. Published by Faculty of Sport Science - Universidad Pablo de Olavide. All rights reserved.