Echocardiographic assessment of myocardial efficiency predicts exercise performance

Cardiac function is a major determinant of cardiopulmonary fitness. This study aimed to determine if novel echocardiographic myocardial function and efficiency parameters at rest can predict exercise performance during different types of prolonged high‐intensity endurance exercise. Echocardiography was performed before exercise in 40 healthy (75% males) 50.3 ± 9.1‐year‐old recreational athletes. Echocardiographic parameters at rest were compared with exercise performance assessed by power output during two different exercises: A lactate threshold and cardiopulmonary exercise test (La‐CPET) and a 91‐km mountain bike sport cycling race. The La‐CPET had a median duration of 43 (40, 45) minutes and a mean power output of 2.9 ± 0.5 W/kg. The race had a median duration of 236 (214, 268) minutes and a mean power output of 2.1 ± 0.5 W/kg. There was moderate left ventricular (LV) dilatation in individuals with the highest performance. The myocardial efficiency parameter, global wasted work (GWW), was positively correlated with race duration (rho = 0.42, p = 0.008) and negatively correlated with mean power output during both the La‐CPET (rho = −0.43, p = 0.007) and the race (rho = −0.44, p = 0.005). In multivariable models, including LV volumes, left GWW remained an independent predictor of race duration (beta = 0.40, p = 0.007) and of mean power output during the La‐CPET (beta = −0.40, p = 0.006) and the race (beta = −0.43, p = 0.003). The novel echocardiographic myocardial efficiency parameter, GWW, measured at rest, is an independent predictor of prolonged high‐intensity endurance exercise performance in healthy middle‐aged athletes. These findings suggest that resting myocardial efficiency parameters may aid the identification of exercise‐induced LV dilatation.