Welk G J, Blair S N, Wood K, Jones S, Thompson R W
Health and Human Performance Department, Iowa State University, Ames 50011, USA.
Med Sci Sports Exerc. 2000 Sep;32(9 Suppl):S489-97. doi: 10.1097/00005768-200009001-00008.
Accelerometry-based activity monitors offer promise for the assessment of free-living physical activity. They provide an objective record of frequency, intensity, and duration of physical activity with minimal burden on participants. The purpose of this study was to evaluate the absolute and relative validity of three contemporary activity monitors (Computer Science and Applications, Inc. [CSA], Tritrac, and Biotrainer) under both laboratory and field conditions.
Fifty-two participants completed two 30-min choreographed routines designed to simulate a variety of lifestyle physical activities. Three different treadmill paces were completed in both routines to evaluate reliability and validity under laboratory conditions. Six different lifestyle activities were also examined to evaluate the validity of the monitors under field conditions. During each routine, the activity levels of participants were monitored with the three activity monitors as well as by indirect calorimetry systems.
The correlations between the monitors and measured VO2 were higher for treadmill activity (mean r = 0.86) compared with lifestyle activity (mean r = 0.55). Correlations among the different monitors were high for both treadmill (r = 0.86) and lifestyle activities (r = 0.70), suggesting that the monitors provide similar information under both conditions. Under laboratory conditions, the CSA yielded accurate predictions of energy expenditure (EE), whereas the Tritrac and Biotrainer tended to overestimate the EE (101-136% of measured value). The Tritrac, however, was found to have less error in individual estimates of EE. Under field conditions, all of the monitors underestimated EE (range: 42-67% of measured value).
The observed differences among the monitors were attributed primarily to differences in the accuracy of the calibration equations rather than to the monitors themselves. Further research is needed to better understand how to use these devices for field-based assessments of physical activity.
基于加速度计的活动监测器有望用于评估自由生活状态下的身体活动。它们能客观记录身体活动的频率、强度和持续时间，且对参与者造成的负担极小。本研究的目的是评估三款当代活动监测器（计算机科学与应用公司[CSA]、Tritrac和Biotrainer）在实验室和现场条件下的绝对效度和相对效度。
52名参与者完成了两套30分钟编排好的日常活动，旨在模拟各种生活方式下的身体活动。在两套日常活动中均完成了三种不同的跑步机速度，以评估实验室条件下的可靠性和效度。还对六种不同的生活方式活动进行了检测，以评估监测器在现场条件下的效度。在每套日常活动期间，使用这三款活动监测器以及间接量热法系统监测参与者的活动水平。
与生活方式活动（平均r = 0.55）相比，跑步机活动中监测器与测得的VO2之间的相关性更高（平均r = 0.86）。对于跑步机活动（r = 0.86）和生活方式活动（r = 0.70），不同监测器之间的相关性都很高，这表明监测器在两种条件下都能提供相似的信息。在实验室条件下，CSA能准确预测能量消耗（EE），而Tritrac和Biotrainer往往高估EE（为测得值的101 - 136%）。然而，发现Tritrac在EE的个体估计中误差较小。在现场条件下，所有监测器都低估了EE（范围：为测得值的42 - 67%）。
监测器之间观察到的差异主要归因于校准方程准确性的差异，而非监测器本身。需要进一步研究以更好地理解如何使用这些设备进行基于现场的身体活动评估。
