Transient cardiac left ventricular diastolic dysfunction following strenuous exercise

The long term clinical significance of exercise-induced “cardiac fatigue” has not been clearly addressed. The aim of this study was to assess the effects of repetitive competitive high altitude running on left ventricular performance. Eleven athletes were studied before and after two high altitude races in two consecutive years. On both occasions 12-lead elettrocardiography (ECG) as well as Doppler echocardiography were performed 24 hours before, shortly after (within 30 min) and 24 hours after the end of the race. Measurements included ejection fraction, early (E) and late (A) transmitral inflow velocities, their ratio (E/A) and percent atrial contribution (AC). Similar studies were performed in 11 age- and sex-matched control subjects at baseline and following a maximal exercise test. Ejection fraction remained stable in both. Conversely, Doppler E/A ratio significantly decreased in atletes early after the race from 1.9±0.1 to 1.3±0.1 (p<0.05) for the first race and from 1.7±0.1 to 1.4±0.1 (p<0.05) for the second race. The decrease was mainly due to a reduction in E (p<0.05), since A was not modified. AC increased from 20%±3% to 28%±5% (p<0.05) and from 21%±3% to 26%±6% (p<0.05), respectively. All parameters returned to baseline at a 24-hour control. Compared to controls, all athletes had significantly higher resting E and A velocities and lower E/A ratio and AC to ventricular filling shortly after exercising. All parameters returned to baseline at the 24-hour controls. These findings are consistent with previous studies reporting transient cardiac fatigue following strenuous exercise. However, the functional effects of these changes do not seem to interfere with cardiac function and athletic performance in both the short term and medium-long term.