Assessment of the left ventricular responses to prolonged exercise has been limited by technology available to assess cardiac tissue movement. Recently developed strain and strain rate imaging provide the unique opportunity to assess tissue deformation in all planes of motion.
Methods and results
Nineteen runners (mean ± SD age; 41 ± 9 years) were assessed prior to and within 60 min (34 ± 10 min) of race finish (Comrades Marathon, 89 km). Standard echocardiography assessed ejection fraction and the ratio of early to atrial ( E / A ) peak transmitral blood flow velocities. Myocardial speckle tracking determined segmental strain as well as systolic and diastolic strain rates in radial, circumferential, and longitudinal planes. Cardiac troponin T (cTnT) assessed cardiomyocyte insult. Ejection fraction (71 ± 5 to 64 ± 6%) and E / A (1.47 ± 0.35 to 1.25 ± 0.30) were reduced ( P < 0.05). Peak strain and peak systolic and diastolic strain rates were altered post-race in circumferential (e.g. peak strain reduced from 21.3 ± 2.4 to 17.3 ± 3.2%, P < 0.05) and radial planes. Some individual heterogeneity was observed between segments and planes of motion. A post-race elevation in cTnT (range 0.013–0.272 µg/L) in 5/12 runners did not differentiate changes in LV function.
Completion of the Comrades Marathon resulted in a depression in ejection fraction, E / A , as well as radial and circumferential strain and strain rates. Group data, however, masked some heterogeneity in cardiac function.