本研究目的在比較跆拳道選手男女與雙腳動態平衡能力的差異，並利用相關及回歸統計分析造成差異的因子。研究對象為30名男子及25名女子高中跆拳道選手，除了進行身高、體重、動態平衡、坐姿體前彎、垂直跳、六角敏捷與簡單視覺反應測量外，也以Y字平衡測驗(Y balance test, YBT)評估雙腳的動態平衡能力，方法是讓受測者分別以左腳或右腳支撐，同時測量對側腳往正前、後內側與後外側三個方向可延伸最長距離，數值再除以腿長得標準化比值。各比值以二因子混合設計變異數分析進行性別和雙腳之間的比較，另以皮爾森積差相關分析YBT數值和各體能因子的相關性，和利用逐步回歸分析找出可預測YBT表現因子。結果顯示男子選手各YBT數值表現顯著優於女子選手，而男女選手慣用和非慣用腳YBT表現組內差異不顯著。YBT數值與垂直跳高度相關性最顯著，其次為身高、年紀和六角敏捷。逐步回歸分析顯示非慣用腳YBT平均表現有40.8%的變異量可用垂直跳和年齡兩因子解釋，慣用腳YBT平均表現則有35.2%的變異量可由身高和年齡解釋。本研究結論為男子選手動態平衡表現優於女子選手，其原因可能與下肢肌力和動作機制的差異有關。

This study aimed to characterize the sex differences and fitness determinants of dynamic balance in high school taekwondo players. Thirty male and 25 female high school taekwondo players were participated in this study. The measurements of stature, weight, and a battery of fitness tests, including vertical jump, sit-and-reach, hexagon agility test and visual reaction time of each player were recorded. In addition, individual dynamic balance was assessed by the Y-balance test (YBT), which requires the subject to stand unilaterally and use the free leg to reach as far as possible in anterior (A), posterior-medial (PM) and posterior-lateral (PL) directions. The reach distances of the dominant and non-dominant legs were then normalized with the length of leg. A two-way mixed model analysis of variance was performed to examine the interaction of sex and legs on the YBT scores, and a multiple stepwise regression analysis was performed to verify the predictors. The results showed that males performed better in the YBT than females, and symmetrical performance of dynamic balance of two legs was found in both male and female players. The YBT scores were significantly correlated to the vertical jump, stature, age and agility. Stepwise regression analysis showed that 40.8% of the variance of the YBT score of non-dominant leg could be explained by vertical jump and stature, and 35.2% of the variance of the YBT score of dominant leg could be explained by stature and age. Our study concludes that sex differences in YBT performance was ascribed primarily to variations in strength and kinematics of the lower extremities of male and female taekwondo players.