Abstract 1586: Left Ventricular Dysfunction After Prolonged Exercise in Middle-Aged Athletes
Purpose: Prolonged exercise has been associated with depressed left ventricular (LV) function in young athletes, yet there are few data for middle-aged men using controlled experimental conditions. The purpose of this study was to examine the effect of prolonged exercise on LV diastolic and systolic function in middle-aged men, and in particular, beta-adrenergic sensitivity.
Methods: Subjects were 12 males with a mean (±sem) age of 43.5±1.9. All were trained cyclists (VO2max=51.7±1.5 ml/kg/min). LV function was assessed before (PRE) and after (POST) 30 minutes of resting recovery following 120 minutes of stationary cycling with fluid replacement, at 75% maximal heart rate. Resting indices of LV diastolic function were obtained at PRE and POST exercise by echocardiography (ECHO) and included pulsed-wave Doppler measures of the IVRT and TD-derived E′ and A′ waves. Primary endpoints of systolic function included TD-derived measures of longitudinal strain (S, %), strain rate (SR, l/s), ejection fraction (EF, %), assessed PRE and POST exercise and during a dobutamine stress protocol (10, 20 and 40 mcg/kg/min).
Results: Plasma catecholamines increased progressively throughout exercise, rising from 3.1±0.4 nmol at rest to 11.0±1.5 nmol (p < 0.001) after 120 minutes of PE. Significant reductions (p<.01) were observed for resting LV diastolic function POST vs. PRE exercise including the IVRT (112.37±12.2 vs. 95.57±9.3), E′ (10.0±2.2 vs. 12.9±1.8). Resting EF was unchanged, however resting LV S and SR were lower POST ex (1.5±0.8 vs.1.2±0.7 l/s, −24±3 vs. −20±3 %, respectively). Dobutamine stress elicited lower measures of of S, SR at both 10 and 20 mcg/kg/min doses, while a depression of EF was only observed at 10 mcg/kg/min.
Conclusions: Prolonged exercise is associated with a post-exercise depression in resting LV diastolic function, with evidence of diminished beta-adrenergic responsiveness in the observed in LV contractile performance.