The impact of endurance exercise training on left ventricular systolic mechanics

Abstract

Although exercise training-induced changes in left ventricular (LV) structure are well characterized, adaptive functional changes are incompletely understood. Detailed echocardiographic assessment of LV systolic function was performed on 20 competitive rowers (10 males and 10 females) before and after endurance exercise training (EET; 90 days, 10.7 Ϯ 1.1 h/wk). Structural changes included LV dilation (end-diastolic volume ϭ 128 Ϯ 25 vs. 144 Ϯ 28 ml, P Ͻ 0.001), right ventricular (RV) dilation (end-diastolic area ϭ 2,850 Ϯ 550 vs. 3,260 Ϯ 530 mm 2 , P Ͻ 0.001), and LV hypertrophy (mass ϭ 227 Ϯ 51 vs. 256 Ϯ 56 g, P Ͻ 0.001). Although LV ejection fraction was unchanged (62 Ϯ 3% vs. 60 Ϯ 3%, P ϭ not significant), all direct measures of LV systolic function were altered. Peak systolic tissue velocities increased significantly (basal lateral SЈ⌬ ϭ 0.9 Ϯ 0.6 cm/s, P ϭ 0.004; and basal septal SЈ⌬ ϭ 0.8 Ϯ 0.4 cm/s, P ϭ 0.008). Radial strain increased similarly in all segments, whereas longitudinal strain increased with a base-to-apex gradient. In contrast, circumferential strain (CS) increased in the LV free wall but decreased in regions adjacent to the RV. Reductions in septal CS correlated strongly with changes in RV structure (⌬RV end-diastolic area vs. ⌬LV septal CS; r 2 ϭ 0.898, P Ͻ 0.001) and function (⌬peak RV systolic velocity vs. ⌬LV septal CS, r 2 ϭ 0.697, P Ͻ 0.001). EET leads to significant changes in LV systolic function with regional heterogeneity that may be secondary to concomitant RV adaptation. These changes are not detected by conventional measurements such as ejection fraction.athlete's heart; left ventricle; strain; ventricular interdependence LEFT VENTRICULAR (LV) structural adaptation in response to aerobic endurance exercise training (EET) has been well characterized. Increases in LV chamber dimensions, wall thickness, and mass have been documented among individuals who participate in EET, and it is these structural attributes that underlie the concept of the "athlete's heart" (8,38,41). At the present time, the impact of EET on LV functional mechanics is less clear.Several reports demonstrate that EET results in enhanced LV diastolic function (3,23,31). In contrast, existing data suggest that LV systolic function is unchanged by EET (9,15,39). Previous studies examining the impact of EET on LV systolic function have relied on indexes such as ejection fraction or fractional area change that may lack the sensitivity to detect regional changes in myocardial function. Novel imaging techniques such as two-dimensional strain and tissueDoppler echocardiography are direct, more sensitive methods of assessing myocardial systolic function (13,14). To date, a prospective and longitudinal assessment of the impact of EET on LV systolic function using these techniques has not been conducted.We hypothesized that EET would result in enhanced resting LV contractility but that this adaptation would be underrepresented by conventional indexes of systolic function. To address this hypothesis, we performed a focused ...

Endurance Exercise and the Right Ventricle

“…In addition, the RV and the interventricular septum, a structure formed by interdigitation of myocardial fibers from both the LV and RV, appears to be particularly susceptible to fatigue following isolated endurance events 6 and sustained periods of training. 7 It is now firmly established that the RV is often markedly dilated among endurance athletes, 8,9 and it has been reported that athletes presenting with symptomatic ventricular arrhythmias commonly demonstrate RV foci. 10 Proarrhythmic patches of fibrosis within the RV and interventricular septum, hypothetically caused by repeated bouts of endurance exercise-induced injury and repair, have been proposed as a unifying pathogenic mechanism.…”

Cardiovascular adaptation in athletes

“…Most data demonstrate that left ventricular function is almost always within the normal range as measured both by ejection fraction and more advanced noninvasive indices of systolic function. 13 However, in clinical practice it is not unusual to see low normal or slightly depressed resting left ventricular function among trained endurance athletes. 14 In our experience; this represents physiologic reserve rather than subclinical pathology as evidenced by normal augmentation and supernormal exercise capacity during provocative laboratorybased exercise testing.…”

Cardiac Imaging in Athletes

“…These indices are not detected by assessment of a global index such as LV ejection fraction. 15,16 As cardiologists, we encounter pathologies such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular dysplasia (ARVD) in our patients, some of whom may be athletes, and differentiating among these entities can be difficult. Knowledge of some morphological distinguishing characteristics can prove vital in diagnosing and managing these cases.…”