Title

Exhaustive Exercise Training Enhances Aerobic Capacity in American Alligator (Alligator Mississippiensis)

Author Info

John Eme, University of California - Irvine
Tomasz Owerkowicz, University of California - Irvine
June Gwalthney, University of California - Irvine
Jason M. Blank, University of California - IrvineFollow
Bryan C. Rourke, California State University - Long Beach
James W. Hicks, University of California - Irvine

Recommended Citation

Published in Journal of Comparative Physiology B, Volume 179, Issue 8, November 1, 2009, pages 921-931.

NOTE: At the time of publication, the author Jason Blank was not yet affiliated with Cal Poly.

The definitive version is available at https://doi.org/10.1007/s00360-009-0374-0.

Abstract

The oxygen transport system in mammals is extensively remodelled in response to repeated bouts of activity, but many reptiles appear to be ‘metabolically inflexible’ in response to exercise training. A recent report showed that estuarine crocodiles (Crocodylus porosus) increase their maximum metabolic rate in response to exhaustive treadmill training, and in the present study, we confirm this response in another crocodilian, American alligator (Alligator mississippiensis). We further specify the nature of the crocodilian training response by analysing effects of training on aerobic [citrate synthase (CS)] and anaerobic [lactate dehydrogenase (LDH)] enzyme activities in selected skeletal muscles, ventricular and skeletal muscle masses and haematocrit. Compared to sedentary control animals, alligators regularly trained for 15 months on a treadmill (run group) or in a flume (swim group) exhibited peak oxygen consumption rates higher by 27 and 16%, respectively. Run and swim exercise training significantly increased ventricular mass (~11%) and haematocrit (~11%), but not the mass of skeletal muscles. However, exercise training did not alter CS or LDH activities of skeletal muscles. Similar to mammals, alligators respond to exercise training by increasing convective oxygen transport mechanisms, specifically heart size (potentially greater stroke volume) and haematocrit (increased oxygen carrying-capacity of the blood). Unlike mammals, but similar to squamate reptiles, alligators do not also increase citrate synthase activity of the skeletal muscles in response to exercise.

Disciplines

Biology

Copyright

2009 by the authors.

Publisher statement

Published by Springer.

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.