Abstract
The purpose of this study was to investigate echocardiographic changes in left ventricular
(LV) diastolic filling and left atrial (LA) strain mechanics following prolonged exercise.
Ten male triathletes completed a 60-min swim, 180-min bike exercise, and a 60-min
all-out run in a laboratory environment. Special attention was paid to prevent dehydration
and energy deficit during the exercise protocol. All participants underwent comprehensive
echocardiographic analyses of Doppler- and volumetric-derived LV diastolic filling
indices and novel speckle-tracking echocardiography (STE)-derived LA strain indices.
LV stroke volume (pre: 108.0±15.9 vs. post: 88.8±19.0 mL; p=0.03) and LA passive emptying
volume (pre: 31.2±7.5 vs. post: 22.4±9.8 mL; p=0.05) were significantly reduced following
the exercise protocol. Of the STE-derived indices of LA function, reservoir and conduit
strain did not change significantly, while there was a trend towards enhanced contraction
strain (pre: 15.1±3.8 vs. post: 19.4±4.8%; p=0.07). Resting heart rate was significantly
higher post-exercise (53.1±5.0 vs. 81.9±16.9 bpm; p<0.001) and its change correlated
strongly with depression of Doppler-derived ratio of early to late ventricular filling
velocities (r=0.74, p=0.01) and reduction of LA passive emptying volume (r=0.86, p=0.01).
Following prolonged exercise, LV stroke volume was reduced due to heart rate related
reduction in LA passive emptying volume whereas global LA strain mechanics were not
compromised in this study.
Key words
exercise-induced cardiac fatigue - cardiac imaging - hydration - atrial fibrillation