Journal of Applied Physiology, Vol 62, Issue 4 1405-1409, Copyright © 1987 by American Physiological Society
Exercise-induced glycogen utilization by the respiratory muscles
C. D. Ianuzzo, M. J. Spalding and H. Williams
Some controversy exists in the literature as to whether or not
diaphragmatic glycogen is utilized during exercise. In this study male
Sprague-Dawley rats were used to determine whether prolonged treadmill
exercise would result in a significant reduction of glycogen concentration
in the respiratory muscles. Untrained rats were run to exhaustion at a
speed of 24 m/min, up a 10% grade. Run time averaged 48:30 min. After
exercise a significant reduction in glycogen was observed in the diaphragm
(43% of control), intercostals (43%), heart (39%), and plantaris (76%). In
the diaphragm a significant reduction was shown in both types I and II
fibers using the periodic acid-Schiff (PAS) stain for glycogen. These
findings show that muscles with vastly different aerobic capacities utilize
endogenous glycogen during moderately intense submaximal endurance exercise
and that the costal diaphragm muscle is not an exception as has recently
been suggested.
