Defense Date


Document Type


Degree Name

Master of Science


Physiology and Biophysics

First Advisor

James L. Poland


In seeking answers to questions about how the human body functions under stressful situations, scientists, coaches, doctors, and athletes in general have all wondered about the role of exercise in the maintenance of good health. Good cardiovascular health, especially, is sought ardently, as it appears to be a major key to overall body fitness. Good cardiovascular health appears to go hand-in-hand with proper diet, proper rest, and proper exercise (1, 2).

The exercise phenomenon has attracted much attention and poses many questions. Just what is occurring when a person or an animal gets "in shape" by exercising. What bodily changes are initiated during exercises which tax the body's metabolic machinery?

To understand better the changes occurring with exercise, it would be of interest to examine and compare the metabolism of cardiac and skeletal muscles. Glycogen is considered a storage form of energy, as it is made up of glucose moieties, and it appears in all metabolizing mammalian cells (3). Yet because the level of glycogen remains at a fairly stable level in resting cells--reflecting a balance of synthesis and degradation of glycogen, any change in that level seen after a stressful situation, such as exercise, could be used as an indication of changes in cell metabolism associated with the stress (3). Thus, a change in the level of glycogen in either heart or skeletal muscle indicates a change in the utilization of energy-providing substrates, of which glycogen is one (A); an alteration in the concentration of the enzymes associated with glycogen synthesis or degradation (5, 6); or a change in some other regulatory mechanism associated with glycogenesis or glycogenolysis (7, 8).

To clarify those changes occurring in the glycogen metabolism of heart and skeletal muscle, the changes can be monitored by measuring differences in glycogen levels in rats after various regimens of exercise and can be related to the conditions under which they happened (4, 9).


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