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

The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises.

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 (W _max) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography.

Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% W _max (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% W _max (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).

Cycling increased LV twist to 30% W _max 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.