本研究目的在探討以非大最大運動攝氧量與心跳率所推算的臨界速度（critical velocity, CV）與傳統運動至衰竭所推算之CV是否有差異存在；並以此強度持續運動30分鐘，進行氧攝氧量、心跳率與積分肌電圖等人體生理反應的變化情形分析，以便確認非最大運動攝氧量及心跳率推算CV方法之有效性。本研究以20名經常參與運動男性大學生（20.45±0.83歲、177.30±6.21公分、71.62±6.45公斤）為受試對象，受試者除了先接受一次最大攝氧量及最大心跳率測驗以外，所有受試者皆需接受四個不同強度跑步的CV測量。進行CV測量時，同時蒐集受試者之攝氧量與心跳率，以利從各強度跑步至90%、80%、和70%目標攝氧量與心跳率之時間推算非最大象動攝氧量與心跳率CV。結果發現以傳統最大努力跑步至衰竭時間所推算的CV(3.54±0.318m/s)與CV□、CV□與CV□(3.64±0.387、3.56±0.410和3.60±0.354m/s)無顯著差異時。同時，本研究以實用性較高及估計標準差最低之CV□持續30分鐘運動時，心跳率會隨著運動時間的增加而上升，RMS下降、攝氧量與MPF則無顯著變化，顯示以此強度運動30分鐘，並無疲勞現象發生。

The purposes of this study were (1) to examine the difference between critical velocity (CV) derived from submaximal exercise time and maximal exercise time, and (2) to examine the validity of CV derived from submaximal exercise time. Subjects were 20 college students (20.45±0.83yrs, 1773.0±6.21cm, 71.62±6.45kg). Participants performed five exhaustive treadmill tests and a 30-min continuous treadmill tests at CV. The purpose of the first test session was to determine VO□ HRmax and ventilatory threshold. At the next four sessions, each subject performed four exhaustive constant velocity test (3.5m/sec~6,/sec). During each test, expired gases and HR were analyzed. CV was derived from submaximal exercise VO□ and HR at each velocity. Secondly, participants performed a 30-min continuous treadmill tests at their CV. During the test, the VO□ Hr and electromyography (RMS & MPF) responses from treadmill were examined, and the validity of CV derived from submaximal exercise time were determined. The results were: (1) CV derived from submaximal exercise time (CV), 3.64±0.387; CV□, 3.56±0.410; CV□, 3.60±0.354m/s and maximal exercise time was (3.54±0.318m/s) not significantly different. (2) When running a 30-min continuous treadmill tests at their CV, HR increased with time, but RMS, MPF and VO□ remain unchanged)