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Effect of changes in load carriage while walking on the left ventricular function in highly trained elderly subjects
Michael Sagiv1, Jacob Ruddoy, Amira Sagiv
1Sports Medicine and Rehabilitation Division, Zinman College of Physical Education and Sport Sciences at the Wingate Institute, Netanya, Israel. sagiv@wincol.macam98.ac.il
Gerontology
|August 10, 2002
Summary
Carrying heavier loads (30 kg vs 20 kg) during treadmill walking increased heart rate and cardiac output in elderly men. However, left ventricular function remained unchanged, suggesting autoregulation dominates in highly trained individuals.
Area of Science:
- Cardiovascular Physiology
- Exercise Science
- Gerontology
Background:
- Isometric stress impacts dynamic exercise performance and left ventricular function more than physical exercise in healthy individuals.
- Previous research indicates varied effects of different exercise types on cardiac responses.
Purpose of the Study:
- To investigate the influence of two distinct load carriage conditions (20 kg vs 30 kg) during treadmill walking on left ventricular function, hemodynamics, and cardiovascular responses in elderly men.
- To assess cardiac and hemodynamic adaptations to combined dynamic and isometric exercise in a trained elderly population.
Main Methods:
- Fifteen aerobically well-trained elderly males (average age 66.1 years) participated in two treadmill walking sessions (30 min each) at 4.5 km/h.
- Subjects carried either a 20 kg or a 30 kg load during separate sessions, with metabolic charts and echocardiography used for assessment.
Main Results:
- The 30 kg load significantly increased heart rate, cardiac output, diastolic blood pressure, mean arterial blood pressure, and left ventricular contractility ratio compared to the 20 kg load (p < 0.05).
- No significant differences were observed in systolic blood pressure, cardiac output, left ventricular volumes, or ejection fraction between the two load conditions.
Conclusions:
- In highly trained elderly individuals, the autoregulation mechanism plays a dominant role during combined dynamic and isometric exercises.
- This autoregulation reduces the afterload to left ventricular ejection, thereby preserving global left ventricular function despite increased external load.