title: Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men.
abstract: OBJECTIVE
  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-1to 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-1to -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).
  
  
  CONCLUSIONS
  Cycling increased LV twist to 30% Wmaxwhich 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.
authors.affiliation: School of Science and Sport, Institute of Clinical Exercise Physiology and Health Science, University of the West of Scotland, Glasgow, UK. alexander.beaumont@uws.ac.uk.
authors.forename: Alexander
authors.initials: A
authors.lastname: Beaumont
authors.affiliation: Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of Bedfordshire, Bedford, UK.
authors.forename: John
authors.initials: J
authors.lastname: Hough
authors.affiliation: School of Science and Sport, Institute of Clinical Exercise Physiology and Health Science, University of the West of Scotland, Glasgow, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Sculthorpe
authors.affiliation: Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of Bedfordshire, Bedford, UK.
authors.forename: Joanna
authors.initials: J
authors.lastname: Richards
mesh_terms: D000293:Adolescent; D000328:Adult; D004452:Echocardiography; D015444:Exercise / Q000502:physiology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007717:Knee / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction; D016277:Ventricular Function, Left
keywords: Exercise; Left ventricle; Rotation; Speckle tracking echocardiography