"Exercise-induced cardiac fatigue"--a review of the echocardiographic literature.

There is growing evidence to support the suggestion that prolonged strenuous exercise has a negative impact on left and right ventricular function during recovery. The main body of evidence covers a 20-year time window with many studies using transthoracic echocardiography to quantify cardiac function. Although studies have addressed different exercise modes and durations most work has been "field" based. During this time period echocardiographic instrumentation and techniques have evolved significantly and their application in the assessment of prolonged exercise has developed in tandem. The primary objective of this article is to provide reflective insight into the phenomenon of "exercise induced cardiac fatigue" by critically evaluating available literature in different competitive field studies or lab-based settings. We achieve this objective by introducing the empirical evidence in relation to echocardiographic modalities employed in developmental order including standard 2D, Doppler, tissue Doppler derived myocardial velocity and strain and myocardial speckle tracking echocardiography and by looking at different modes and duration of exercise. The insights provided by data based on each technique are critically reviewed, contradictory findings are explored and the potential for further work is identified. Furthermore the clinical implications and proposed mechanisms of "exercise-induced cardiac fatigue" are also explored.