Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men

Abstract

Purpose: The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises. Methods: Twenty-six healthy male participants (age = 30.42 ± 6.17 years) were used to study peak twist mechanics at rest and during incremental semi-supine cycling at 30 and 60% work rate maximum (Wmax) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography. Results: Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% Wmax (13.21° ± 4.63° to 20.04° ± 4.76°, p < 0.001) then remained unchanged. LV systolic and diastolic twisting velocities progressively increased with exercise intensity during cycling from rest to 60% Wmax (twisting, 88.21° ± 20.51° to 209.05° ± 34.56° s−1, p < 0.0001; untwisting, −93.90 (29.62)° to −267.31 (104.30)° s−1, p < 0.0001). During the knee extension exercise, LV twist remained unchanged with progressive intensity (rest 13.40° ± 4.80° to 75% MVC 16.77° ± 5.54°, p > 0.05), whilst twisting velocity increased (rest 89.15° ± 21.77° s−1 to 75% MVC 124.32° ± 34.89° s−1, p < 0.01). Untwisting velocity remained unchanged from rest [−90.60 (27.19)° s−1] to 40% MVC (p > 0.05) then increased from 40 to 75% MVC [−98.44 (43.54)° s−1 to −138.42 (73.29)° s−1, p < 0.01]. Apical rotations and rotational velocities were greater than basal during all conditions and intensities (all p < 0.01). Conclusion: Cycling increased LV twist to 30% Wmax which then remained unchanged thereafter, whereas twisting velocities showed further increases to greater intensities. A novel finding is that LV twist was unaffected by incremental knee extension, yet systolic and diastolic twisting velocities augmented with isometric exercise.