title: Effect of changes in load carriage while walking on the left ventricular function in highly trained elderly subjects.
abstract: BACKGROUND
  In previous studies, the effect of isometric stress on the dynamic performance of a graded exercise test in normal subjects augmented afterload and brought about changes in left ventricular function more often than did results from physical exercise.
  
  
  OBJECTIVE
  This study used the metabolic charts and echocardiography to examine the influence of two different types of load carriage during 30 min of treadmill walking on left ventricular function, hemodynamics, and cardiovascular responses.
  
  
  METHODS
  Fifteen elderly (age 66.1 +/- 3.5 years) aerobically well-trained male subjects (VO(2 peak) 44.2 +/- 5.0 ml x kg(-1) x min(-1)) volunteered in this study. The subjects walked on a treadmill (at a speed of 4.5 km x h(-1)), carrying a load of 20 kg during one session and a load of 30 kg during a second session.
  
  
  RESULTS
  Following the 30-min exercise in each session, significant (p < 0.05) differences were noted between the 20-kg and the 30-kg work loads with regard to cardiac output (6.8 +/- 0.5 and 7.8 +/- 0.4 l.min(-1)), heart rate (114.0 +/- 11.0 and 126.0 +/- 10.0 beats.min(-1)), diastolic blood pressure (79.4 +/- 5.0 and 84.3 +/- 5.0 mm Hg, mean arterial blood pressure (104.0 +/- 4.0 and 109.2 +/- 3.0 mm Hg), and left ventricular contractility ratio (3.3 +/- 0.4 and 3.6 +/- 0.3). No significant differences were noted between the work loads with regard to systolic blood pressure, cardiac output, left ventricular volumes, and ejection fraction.
  
  
  CONCLUSIONS
  This study suggests that in the highly trained elderly, the influence of the autoregulation mechanism dominates during combined dynamic and isometric exercises, thus the opposing force to the left ventricular ejection is reduced which in turn does not change left ventricular global function.
authors.affiliation: Sports Medicine and Rehabilitation Division, Zinman College of Physical Education and Sport Sciences at the Wingate Institute, Netanya, Israel. sagiv@wincol.macam98.ac.il
authors.forename: Michael
authors.initials: M
authors.lastname: Sagiv
authors.forename: Jacob
authors.initials: J
authors.lastname: Ruddoy
authors.forename: Amira
authors.initials: A
authors.lastname: Sagiv
authors.forename: Shlomo
authors.initials: S
authors.lastname: Ben-Gal
authors.forename: David
authors.initials: D
authors.lastname: Ben-Sira
mesh_terms: D000368:Aged; D004452:Echocardiography; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*; D016138:Walking / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*