Levine J, Melanson E L, Westerterp K R, Hill J O
Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA.
Eur J Clin Nutr. 2003 Sep;57(9):1176-80. doi: 10.1038/sj.ejcn.1601673.
Walking is an important mode of exercise and is likely to represent a major component of nonexercise activity thermogenesis. The question arises, how best to quantify walking-energy expenditure (EE) in free-living individuals. The triaxial accelerometer for movement registration (Tracmor) is a valid measure of body displacement and so we wanted to evaluate this tool for quantifying walking-EE.
In this study, we test the hypothesis that walking-EE, measured in a Room Calorimeter, can be predicted from Tracmor output using a regression equation derived from a brief Tracmor/treadmill/Metabolic Cart protocol.
First, 11 healthy subjects completed a 40-min procedure whereby they wore a Tracmor unit and walked on a treadmill at 0, 1, 2 and 3 mph while EE was measured using a Metabolic Cart. This allowed a regression equation to be defined for each subject to convert Tracmor output to EE. Each subject then entered a Room Calorimeter wearing the Tracmor Unit and walked at two self-selected velocities ('slow', 'fast') while EE was measured. 'Tracmor/regression equation' predictions of walking-EE were compared with Room Calorimeter measurements of walking-EE for the two velocities.
The 'Tracmor/regression equation' prediction of EE for walking slowly was 6.36+/-1.67 kJ/min, and for walking fast it was 11.0+/-2.60 kJ/min. Room Calorimeter measurements were 6.43+/-1.85 and 10.9+/-3.03 kJ/min, respectively. The intraclass correlation coefficient for slow-paced walking was 0.93 (P<0.001), and for fast-paced walking it was 0.82 (P<0.005).
When combined with laboratory measures of EE, the Tracmor accelerometer provides useful data on walking-EE and is applicable to free-living individuals.
步行是一种重要的锻炼方式，可能是日常非运动活动产热的主要组成部分。问题在于，如何最好地量化自由生活个体的步行能量消耗（EE）。用于运动记录的三轴加速度计（Tracmor）是一种有效的身体位移测量工具，因此我们想评估该工具用于量化步行EE的情况。
在本研究中，我们检验这样一个假设，即使用从简短的Tracmor/跑步机/代谢车方案推导得出的回归方程，可根据Tracmor输出预测在房间热量计中测得的步行EE。
首先，11名健康受试者完成了一个40分钟的流程，在此期间他们佩戴Tracmor装置，并在跑步机上以0、1、2和3英里/小时的速度行走，同时使用代谢车测量EE。这使得能够为每个受试者定义一个回归方程，将Tracmor输出转换为EE。然后，每个受试者佩戴Tracmor装置进入房间热量计，并以两种自行选择的速度（“慢”、“快”）行走，同时测量EE。将两种速度下步行EE的“Tracmor/回归方程”预测值与房间热量计测量值进行比较。
慢步行走时EE的“Tracmor/回归方程”预测值为6.36±1.67千焦/分钟，快步行走时为11.0±2.60千焦/分钟。房间热量计测量值分别为6.43±1.85和10.9±3.03千焦/分钟。慢步行走的组内相关系数为0.93（P<0.001），快步行走的组内相关系数为0.82（P<0.005）。
当与EE的实验室测量相结合时，Tracmor加速度计可提供有关步行EE的有用数据，并且适用于自由生活个体。
