本研究目的在探討速度-時間非線性模式 (V-T) 、速度-時間倒數線性模式 (V-1/t)、距離-時間線性模式 (D-T)、三參數非線性模式 (3P) 所得之臨界速度 (critical velocity；CV) 和乳酸閾值速度 (OBLA) 的差異及其與運動表現的相關。受試對象為18名國內優秀青少年游泳選手，所有受試者皆需接受(1) 25m、50m、100m、200m、400m最大努力捷泳測驗，再以此成績利用SAS統計軟體計算各種數學模式之CV；(2)兩次不同速度 (85%和100%) 400m捷泳測驗後，採取指尖血液分析乳酸值，再利用插補法推算4mmol/L乳酸閾值速度。結果發現除3P非線性模式與OBLA無顯著差異外，其餘各數學模式之CV皆與OBLA達顯著差異水準；各種數學模式之CV和OBLA分別與運動表現的相關皆達之顯著水準 (r = 0.80 ~0.99；0.72~0.99)，顯示各種數學模式之CV，適用於青少年游泳選手，且可有效評估有氧運動能力。但是，不同數學模式之CV並不相同，以3P非線性模式之CV最低，D-T線性模式的計算方法最簡便，兩者相關係數更高達0.97，因此，可利用迴歸公式：3P模式 CV = 0.8905×D-T模式CV +0.2146，增進臨界負荷的實用性。

The purposes of this study are to examine the difference between critical power (CP) derived from various mathematical models (V-T nonlinear model, V-1/t linear model, D-T linear model and 3P nonlinear model) and the onset of blood lactate accumulation (OBLA). Subjects are 18 juvenile swimmers. First, each subject swam five different distances (25m、50m、100m、200m and 400m with freestyle) at their maximal effort and the time to complete each distance was recorded for assessing critical velocity by various mathematical models. Secondly, the subjects swam 400m twice: once at maximal effort and the other, at a constant velocity of 85% of mean velocity of maximal effort. The swimming velocity corresponding to the OBLA was determined by extrapolation. The results were: 1) only 3P nonlinear model produced an estimate of CV that was not significantly different from the OBLA, and was considered as one of the best mathematical models. 2) the coefficient of correlation between the performance of all distances with OBLA｛nd CV of various mathematical models were high (0.72~0.99). The longer the swimming distance the coefficient of correlation was found.