Exercise-Induced Cardiac Fatigue in Soldiers Assessed by Echocardiography

Cardiac function and autonomic cardiac function during a multi-stage cycling event: a brief report

Introduction

Prolonged and repeated exercise performed during an ultra-endurance event can induce general and cardiac fatigue known as exercise-induced cardiac fatigue. Our objective was to find a possible correlation between the cardiac function and the autonomic cardiac function.

Methods

During a multistage ultra-endurance event, a female well-trained cyclist underwent daily rest echocardiography and heart rate variability measurements to assess the cardiac function and the cardiac autonomic function.

Results

The athlete completed 3,345 km at 65% of her maximum heart rate and 39% of her maximum aerobic power. A progressive improvement of the systolic function for both the left ventricle and the right ventricle was observed during the event.

Discussion

Alterations were observed on the cardiac autonomic function with an imbalance between sympathetic and parasympathetic, but there was no sign of a significant correlation between the cardiac function and the autonomic cardiac function and no signs of cardiac fatigue either. Further analysis should be performed on a larger sample to confirm the obtained results.

The Influence of Special Military Training on Left Ventricular Adaptation to Exercise in Elite Air Force Soldiers

Purpose

The purpose of this study was to observe the influence of level physical training intensity on left ventricular (LV) adaptation in elite air force soldiers compared to regular basic military training.

Methods

The LV adaptation of special military physical training for elite air force soldiers was compared with basic military training for regular troops. A group of the nonmilitary subject was also evaluated as a control group. The presence of LV adaptation was evaluated using some echocardiography parameters, including LV mass index (LVMI), LV ejection fraction (LVEF), global longitudinal strain (GLS), and myocardial work index. The parameters of the myocardial work index include global constructive work (GCW), global wasted work (GWW), global work index (GWI), and global work efficiency (GWE).

Results

Forty-three elite air force soldiers underwent special military training, 43 regular troops underwent basic military training, and 23 nonmilitary subjects as a control group. Age, heart rate, blood pressure, and Cooper test results significantly differed among the three groups. Multivariate analysis among all groups showed that the level of physical training was associated with the LVMI (coefficient β = 6.061; 95% confidence interval [CI] = 1.91-10.22; P = 0.005), LVEF (coefficient β = -1.409; 95% CI = -2.41-[-0.41]; P = 0.006), LVGLS (coefficient β = 1.726; 95% CI = 1.20-2.25; P < 0.001), GWW (coefficient β = -13.875; 95% CI = -20.88-[-6.87]; P < 0.001), GWE (coefficient β = 0.954; 95% CI = 0.62-1.26; P < 0.001), GCW (coefficient β = 176.128; 95% CI = 121.16-231.10; P < 0.001), and GWI (coefficient β = 196.494; 95% CI = 144.61-248.38; P < 0.001).

Conclusions

Higher intensity of physical training observed in a special military training is associated with higher LV GLS, GWE, GCW, GWI, and lower GWW value suggesting greater physiological adaptation than the lower intensity training.

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

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.

Impact of long-lasting moderate-intensity stage cycling event on cardiac function in young female athletes: A case study

PURPOSE

Effects of intense and/or prolonged exercise have been studied extensively in male athletes. Nevertheless, data are scare on the effect of long duration events on cardiac function in female athletes. Our aim was to investigate the effect of a long-lasting moderate-intensity stage cycling event on cardiac function of young female athletes.

METHODS

Seven well-trained female cyclists were included. They completed a cycling event of 3529 km on 23 days. All underwent an echocardiography on 6 time-points (baseline and at the arrival of day (D) 3, 7, 12, 13 and 23). Cardiac function was assessed by conventional echocardiography, tissue Doppler imaging and speckle tracking techniques. Daily exercise load was determined by heart rate (HR), power output and rate of perceived exertion data (RPE, Borg scale).

RESULTS

All stages were mainly done at moderate intensity (average HR: 65% of maximal, average aerobic power output: 36% of maximal, average RPE: 4). Resting HR measured at the time of echocardiography did not vary during the event. Resting cardiac dimensions did not significantly change during the 23 days of cycling. No significant modification of cardiac function, whatever the studied cavity, were observed all along the event.

CONCLUSION

The results suggest that, in the context of our case study, the long-lasting moderate-intensity stage cycling event was not associated with cardiac function alteration. Nevertheless, we must be careful in interpreting them due to the limits of an underpowered study.