背景與目的：研究目的是為探討三度空間加速規於跑步機行走之向量大小及能量消耗與耗氧量相關性，了解加速規量化身體活動的能量消耗之可行性及可能的限制。方法：徵求18至30歲且身體健康的自願者在跑步機上行走，同時使用間接量熱計(metabolic cart，SensorMedics，Vmax 29)量測耗氧量，三度空間加速規測量身體活動向量大小及能量消耗。受試者隨機在三種不同速度、坡度跑步機上行走（共九種測試，速度分別為2、3、4mph，坡度分別為0%、3.5%、7%），每次行走5分鐘，兩次測試間至少間隔5分鐘，直到受試者心跳回復至休息狀態再進行下一項測試。實驗結果選取每次測試的第2至4分鐘的平均值作為資料分析，以SPSS/PC 10.0軟體進行統計分析。結果：共有20位自願者（男、女各10人，平均年齡23.5±2.3歲）完成所有測試。在全部的測試中，三度空間加速規所評估的能量消耗和測得的向量大小，分別與間接量熱計有顯著相關(r=0.8，p<0.1，r=0.65，p<0.01)。若分別比較在0%、3.5%、7%三種不同的跑步機坡度時，三度空間加速規所評估的能量消耗和測得的向量大小，與間接量熱計的相關分別為r=0.94，0.78和r=0.95，0.77和r=0.94，0.76（p值全都<.01）。而在2、3、4mph三種不同的跑步機速度時，其相關則分別為r=0.26(p<0.05)，-0.42(p<0.01)和r=0.39(p<0.01)，-0.27(p<0.05)和r=0.41(p<0.01)，-0.27(p<0.05)。結論：三度空間加速規測量在跑步機上行走時的能量消耗，可以有效感應速度變化，但對坡度變化較不敏感，且易高估能量消耗數值。雖有其應用上限制，對於行走相關的研究，仍是方便可行的能量消耗評估工具。

Purpose: The research purpose is to investigate correlation between triaxial accelerometer measured vector magnitude, energy consumption and oxygen consumption during treadmill walking. Methods: Twenty young and apparently healthy subjects were recruited to participate in this study. All subjects randomly walked on treadmill under 9 conditions (speed 2, 3, 4 mph combined with slope 0%, 3.5% and 7 %). Each exercise lasted for 5 minutes and there were at least 5 minutes rest time in between. The triaxial accelerometer (RT3) and indirect calorimetry were used simultaneously. Results: Mean age of subjects is 23.5 ±2.3 years. RT3 energy consumption vs. indirect calorimetry and RT3 vector magnitude vs. indirect calorimetry are both highly correlated (r=0.8, p<0.01, r=0.65, p<0.01). Under 0%, 3.5%, 7% three different slopes, correlations between RT3 energy consumption and vector magnitude vs. indirect calorimetry are r=.94, .78, r=.95, .77 and r=.94, .76 (p all<0.01). While under 2, 3, 4 mph three different speed, correlations between RT3 energy consumption and vector magnitude vs. indirect calorimetry are r=0.26 (p<0.05), -0.42(p<0.01), r=0.39 (p<0.01). -0.27 (p<0.05), r=0.41 (p<0.01), -0.27 (p<0.05). Conclusions: RT3 is significantly correlated with oxygen consumption in evaluating energy consumption during treadmill walking, although it is more sensitive to change of speed rather than change of slope and tend to overestimate energy consumption.