目的：本研究主要在評估經由訓練兩年以上的韻律體操國小女童與一般國小女童在平衡能力上是否有差異，方法：實驗對象分為兩組：韻律體操組包括20 名國小韻律體操代表隊女選手(9±2 歲)，訓練年齡至少2 年以上；非運動組包括20 名一般生未曾經過運動訓練的學生(9±2 歲)，透過Lafayette 左右動態平衡儀做為檢測工具，並記錄實驗參與者站立於平衡儀上20 秒內在左、中、右搖晃次數，以不同組別(韻律體操組與一般組)及不同位置(左、中、右)為自變項，搖晃次數為依變項，採用混合設計二因子變異數分析(Mixed design Two-way ANOVA)進行考驗，若交互作用有顯著差異，則進一步以單純主要效果考驗其差異性。結果：不同組別與位置等二因子間有交互作用關係存在(F=3.93,p<.05)，經單純主要效果考驗後發現，不同組別在中間位置有顯著差異(F=8.53,p<.05)，且韻律體操隊晃動次數低於一般組；而韻律體操組在不同位置有顯著差異(F=7.20,p<.05)且在左側之晃動次數低於右側並低於中間；一般組在不同位置一有顯著差異(F=29.91,p<.05)，且在右側之晃動次數低於左側並低於中間。結論：不同組別與不同位置之間有交互作用的關係存在，體操組在中間位置的平衡能力明顯優於一般組，顯示出平衡能力對韻律體操選手的重要性。而不論體操組或一般組，其在中間位置之平衡能力皆明顯優於左側與右側，顯示將重心留在中間是保持平衡的最佳模式。

Purpose：this research aims to study whether there is difference on the balancing ability between elementary-school rhythmic gymnastics girl athletes trained for more than two years and ordinary elementary-school girls. The method：the experimental subjects are divided into rhythmic gymnastics group and ordinary group. The former group includes 20 elementary-school rhythmic gymnastics girl athletes (at the age of 9, plus or minus 2) trained for more than two years；the other one includes 20 ordinary students(at the age of 9, plus or minus 2) never trained, Using Lafayette dynamic balancing apparatus, with different groups(rhythmic gymnastics group and ordinary group) as well as different positions(left, middle, right) as independent variables, and times of faltering as the dependent variable, this study records faltering times in 20 seconds of objects standing on the left, the middle, and the right of balancing apparatus,distinctively, and then use mixed design two-way ANOVA to examine records. Furthermore, single major effect is to be examined if there is apparent difference on the interaction effect. Result：there is interaction effect existing between two factors, group and position(F=3.93, p<.05). By single major effect examination,there is apparent difference on the middle position between different groups(F=8.53, p<.05) with less times of faltering of rhythmic gymnastics athletes than that of ordinary students. For rhythmic gymnastics athletes,apparent difference exists between different positions(F=7.20, p<.05) with faltering times of the left less than that of the right and that of the middle; for ordinary students, there is apparent difference between different positions with faltering times of the right less than that of the left and that of the middle. Conclusion：There are interaction effects existing between different groups andbetween different positions. Rhythmic gymnastics athletes' balancing ability on the middle position are better than ordinary students, which reveals the balancing ability counts for rhythmic gymnastics athletes. Furthermore, whether rhythmic gymnastics athletes or ordinary students perform better balancing abilities on the middle position than on the other two, which proves focusing on the middle position is the best way to keep balance.