Background: Aging-related changes occur mainly in the cardiopulmonary system and skeletal muscles, bringing about a reduction in physical performance. Consequently, maximal oxygen uptake (VO2max) decreases. Objectives: The current study investigated exercise oxygen utilization during maximal aerobic exercise in trained and untrained elderly. Methods: Fifteen trained (59.3 ± 1.1 years) and 15 untrained (60.1 ± 1.1 years) elderly underwent a peak cardiopulmonary exercise test on a bicycle ergometer. Arterial O2 was defined from echocardiograph and venous oxygen content. Results: At rest, trained compared to untrained elderly had significantly (p < 0.05) higher values of end diastolic volume (108.1 ± 5.8 and 100.7 ± 6.2 ml, respectively) and stroke volume (68.1 ± 4.3 and 57.3 ± 6.5 ml, respectively), while heart rate (68.7 ± 9.3 and 81.3 ± 8.2 beats · min–1, respectively), and mean arterial blood pressure (90.6 ± 6.9 and 95.4 ± 7.2 mm Hg, respectively) were significantly lower. At peak aerobic test, the trained elderly, compared to the untrained subjects, achieved significantly (p < 0.05) higher values of end diastolic volume (156.1 ± 8.2 and 134.1 ± 7.6 ml, respectively), stroke volume (123.0 ± 7.9 and 96.0 ± 4.8 ml, respectively), cardiac output (20.2 ± 1.5 and 15.0 ± 1.3 liters·min–1, respectively) and oxygen uptake (42.1 ± 2.1 and 31.1 ± 2.4 ml·kg–1·min–1, respectively), while diastolic blood pressure (70.3 ± 5.6 and 77.5 ± 4.2 mm Hg, respectively) and total peripheral resistance [4.3 ± 0.8 and 5.9 ± 1.41 (dyn·s–1·cm–5)·10–1, respectively], were significantly (p < 0.05) lower. Conclusions: The present study suggests that the differences between trained and untrained elderly in absolute oxygen uptake of the working muscles and peak power output at maximal exercise test are due to physical activity status. The higher aerobic capacity in the trained elderly is related to increased cardiovascular function and to a lesser extent to increased muscle mitochondria concentration and capillarity. Although untrained elderly have reduced maximal oxygen uptake at peak aerobic exercise, intrinsic regulation of mitochondrial function does not seem to be significantly altered because of aging associated physical inactivity. Therefore, untrained elderly can partially compensate for their lower cardiac output by increasing oxygen extraction to levels comparable with those of trained elderly.

Keywords:
Strenuous exercise, Echocardiograph, Cardiac output, Fick equation, Oxygen extraction
This content is only available via PDF.
© 2007 S. Karger AG, Basel
2007
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.