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Effects of Various Feeding and Exercise Regimens on Rat Growth and Survival¹

McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin 53706

The present study was undertaken to obtain additional information on the effects of various feeding and exercise regimens on rat growth and survival. In three experiments, groups of rats, maintained on cycles of 12 hours of light and 12 hours of dark, were trained to various combinations of feeding and voluntary exercise regimens. Rat weights and the amounts of exercise were monitored throughout the experimental periods. At the end of two of the experiments, rats were killed at different times of day, and the weights of several organs were taken. In addition, the activities of several liver enzymes such as tyrosine aminotransferase and ornithine decarboxylase were determined. Data concerning the effects of various combinations of dietary regimens and voluntary exercise indicated that a critical age and period of pretraining on a restricted feeding schedule must be reached to insure that rats will survive repetitive 40-hour fasts after 8-hour feeding periods along with vigorous voluntary exercise. The liver enzyme data indicated that, in surviving rats, the activities of several liver enzymes underwent changes in response to feeding. Some differences between the metabolic states of exercised and nonexercised rats may exist.

KEY WORDS: • controlled feeding • exercise • tyrosine aminotransferase • ornithine decarboxylase • glucose-6-phosphate dehydrogenase

¹ Financial support was provided in part by grants CA-07175 and T01-CA-5002 from the National Cancer Institute.

² Recipient of a USPHS postdoctoral fellowship (1-F02-CA-52268-01) awarded by the National Cancer Institute.

³ Recipient of a USPHS postdoctoral fellowship (1-F02-CA-51304-01) awarded by the National Cancer Institute. Present address: New York State Department of Health, New Scotland Avenue, Albany, New York, 12201.

⁴ Present address: Department of Pediatrics, Division of Radiobiology and Biophysics. University of Virginia, School of Medicine, Charlottesville, Virginia 22901.

⁵ Recipient of a Damon Runyon Memorial Fund postdoctoral fellowship. Present address: Department of Biochemistry, University of Sheffield, S10 2TN, United Kingdom.

⁶ To whom requests for reprints should be sent.

Manuscript received 30 April 1973.