Effects of Physical Exercise on the Jaw Bones of the Rat at the Growth Stage

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It is considered that inadequate exercise and calcium intake has an influence on bone tissue in growth stage, but no report has been found on the effect of physical exercise and calcium intake on developing jaw.Male Wistar rats of 4-week-old were subjacted to running exercise with different calcium-content feeding for 4 weeks to investigate change of tibia meta-physis, comparing with mandible. Control group : no exercise, with standard diet. Standard 1-exercise : running exercise of 20 m/min, 1h/time/day, 5 times/week. Standard 2-exercise : the way as in 1-exercise group but 2 times/week. Calcium-doficient no-exercise, calcium-deficient 1-exercise, and calcium-doficient 2-exercise group were subjected to the exercise as in standard group, fed with calcium deficient diet. The results were as follows. 1. Mandible 1) Bone density, 2) Ca and P quantitative analysis with microanalyzer, 3) histopathological, 4) SEM,5) compression strength examination did not showed any change deriving from running exercise, considering the developing mandible was subjected to the normal occlusal and masticantory forse. 2. Tibia metaphysis SEM investigation revealed activated development of chondrocyte layr in 2-exercise group fed with standard diet, comparing with those no exercise stress was applied in. The trabeculae was demonstrated more thick, arrangement more regular, and bone mass increased, implying that formation of bone matrix was improved.Considering the above findings, it was concluded that exercise was effective in promoting the bone formation in growth stage.