Groups of weanling and newborn Sprague-Dawley rats were each subjected to a specific 10% simulated increase in body weight to a maximum of a doubling of body weight, using constant centrifugation, to study the effects of quantified, increased, intermittent, compressive forces on the histomorphology of the proximal tibial epiphysial growth plate. The weanling rats were sacrificed after 30 and 60 days of centrifugation; the newborn rats were sacrificed after 90 days of centrifugation. The results demonstrated no prominent changes in histomorphology, when compared to the controls, in the weanling rats sacrificed at 30 days of centrifugation, or in newborn rats subjected to 90 days of centrifugation; however, a prominent thinning of the growth plates was observed in the weanling rats sacrificed at 60 days of centrifugation.