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. 2023 Jan 11:9:1081664.
doi: 10.3389/fcvm.2022.1081664. eCollection 2022.

Myocardial inefficiency is an early indicator of exercise-induced myocardial fatigue

Christine Bjørkvik Erevik  1 , Øyunn Kleiven  1 , Vidar Frøysa  1 , Magnus Bjørkavoll-Bergseth  1 , Monica Chivulescu  2 , Lars Gunnar Klæboe  2 , Lars Dejgaard  2 , Bjørn Auestad  3   4 , Øyvind Skadberg  5 , Tor Melberg  1 , Stig Urheim  6 , Kristina Haugaa  2 , Thor Edvardsen  2 , Stein Ørn  1
Affiliations

Myocardial inefficiency is an early indicator of exercise-induced myocardial fatigue

Christine Bjørkvik Erevik et al. Front Cardiovasc Med. .

Abstract

Background: The effect of prolonged, high-intensity endurance exercise on myocardial function is unclear. This study aimed to determine the left ventricular (LV) response to increased exercise duration and intensity using novel echocardiographic tools to assess myocardial work and fatigue.

Materials and methods: LV function was assessed by echocardiography before, immediately, and 24 h after a cardiopulmonary exercise test (CPET) and a 91-km mountain bike leisure race. Cardiac Troponin I (cTnI) was used to assess myocyte stress.

Results: 59 healthy recreational athletes, 52 (43-59) years of age, 73% males, were included. The race was longer and of higher intensity generating higher cTnI levels compared with the CPET (p < 0.0001): Race/CPET: exercise duration: 230 (210, 245)/43 (40, 45) minutes, mean heart rate: 154 ± 10/132 ± 12 bpm, max cTnI: 77 (37, 128)/12 (7, 23) ng/L. Stroke volume and cardiac output were higher after the race than CPET (p < 0.005). The two exercises did not differ in post-exercise changes in LV ejection fraction (LVEF) or global longitudinal strain (GLS). There was an increase in global wasted work (p = 0.001) following the race and a persistent reduction in global constructive work 24 h after exercise (p = 0.003).

Conclusion: Increased exercise intensity and duration were associated with increased myocardial wasted work post-exercise, without alterations in LVEF and GLS from baseline values. These findings suggest that markers of myocardial inefficiency may precede reduction in global LV function as markers of myocardial fatigue.

Keywords: athletes heart; exercise; exercise-induced cardiac fatigue; left ventricular function; myocardial efficiency; myocardial strain; myocardial work; sports cardiology.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Flow chart of the study.
FIGURE 2
FIGURE 2
The percentual change of echocardiographic measurements from baseline (before exercise) and immediately and 24 h following a cardiopulmonary exercise test (CPET) and the North Sea Race in 2018 (Race). The following parameters were assessed (A) LVEF (left ventricular ejection fraction), (B) GLS (global longitudinal strain), (C) GWI (global work index), (D) GCW (global constructive work), (E) GWW (global wasted work), and (F) GWE (global work efficiency). *p < 0.05.
FIGURE 3
FIGURE 3
Representative global pressure-strain loops from the same person after (A) cardiopulmonary exercise test (CPET) and (B) Race. GWI, Global work index. Amount of myocardial work performed by the left ventricle during systole: Area of the pressure-strain loop from mitral valve closure to mitral valve opening (A + B + C). GCW, Global constructive work. Work that contributes to left ventricular ejection. Positive work performed in (B) systole (shortening) + negative work performed in (C) isovolumetric relaxation (lengthening). GWW, Global wasted work. Work that does not contribute to left ventricular ejection. Negative work performed in (B) systole (lengthening) + positive work performed in (C) isovolumetric relaxation (shortening).
See this image and copyright information in PMC

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