本研究的目的在探討臨界負荷(Critical power)、肌電圖疲勞閾值(Fatigue Threshold of Electromyogram)與無氧閾值(Anaerobic Threshold)的相關與差異性。受試者為10名經常運動的大學男學生，平均年齡21.50±4.06歲，身高172.00±3.89公分，體重67.00±6.00公斤。所有受試者接受一次漸增負荷的腳踏車運動測驗，以測量無氧閾值，以及四次平衡次序的固定負荷(220、260、300、340 watt)之最大持續運動時間與慣用腳股四頭肌積分肌電圖(IEMG)測量。結果發現肌電圖疲勞閾值的負荷最高(206.00±10.14 watt)，臨界負荷次之(184.90±13.25watt)，無氧閾值則最低(173.20±13.86watt)，三者間皆有顯著的差異存在。臨界負荷與無氧閾值的相關為0.91，臨界負荷舆肌電圖疲勞閾值的相關為0.44，肌電圖疲勞閾值與無氧閾值的相關為0.41。本研究顯示，臨界負荷可以做為評估無氧閾值的根據，其迴歸方程式為
無氧閾值(watt)=0.955×臨界負荷(watt)－3.314
但是，本研究無法證實肌電圖疲勞閾值，是評估無氧閾值的好方法。
由於臨界負荷在測量與判定上，皆此無氧閾值簡便，而且其與無氧閾值具有高度相關，因此是有效評估無氧閾值能力的測驗。
The prupose of this study was to investigate the difference and relationship among Critical Power (CP), Fatigue Threshold of Electromyogram (EMGFT) and Anaerobic Threshold (AT). Ten male subjects with average age of 21.50±4.06 ys, height of 172.00±3.89cm and body weight of 67.00±6.00 kg, voluntarily participated in this study. Exhaustive exercise protocol, started with 80W, increased 30W per 3 minutes was used to measure AT. Time to exhaustion and integrated electromyogram (IEMG) of preference leg's quadriceps during submaximal cyclings with workloads of 220,260,300 and 340W were recorded to evaluate CP and EMGFT respectively. Significant difference (p＜.05) among CP, EMGFT and AT was found. Significant correlation (r=0.91) was observed between CP and AT. There is no significant correlation between CP and EMGFT, and between EMGFT and AT. It is concluded that CP, but not EMGFT, is a reliable predictor of AT.
