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

认为运动和钙摄入不足对生长期的骨组织有影响，但关于运动和钙摄入对颌骨发育的影响尚未见报道。4周龄雄性Wistar大鼠进行不同钙含量的跑步运动，饲养4周，观察胫骨和下颌骨的变化。对照组：不运动，按标准饮食。标准1-锻炼：跑步锻炼20米/分钟，1小时/时间/天，每周5次。标准2-运动：方法同1-运动组，但每周2次。缺钙不运动组、缺钙1运动组、缺钙2运动组与标准组相同进行运动，给予低钙饮食。研究结果如下：1.下颌骨1)骨密度，2)钙磷定量分析，3)组织病理学，4)扫描电子显微镜，5)抗压强度检查未见任何变化，考虑到发育中的下颌骨受到正常的咬合和咀嚼应力的影响。2.胫骨干骺端扫描电子显微镜观察发现，与未给予运动应激组相比，给予标准饲料的2次运动组软骨细胞层发育活跃。骨小梁增厚，排列规则，骨量增加，提示骨基质的形成得到改善，提示运动对生长期的骨形成有促进作用。

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.