Rothney Megan P, Apker Gregory A, Song Yanna, Chen Kong Y
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.
J Appl Physiol (1985). 2008 Oct;105(4):1091-7. doi: 10.1152/japplphysiol.90641.2008. Epub 2008 Jul 17.
ActiGraph accelerometers are a useful tool for objective assessment of physical activity in clinical and epidemiological studies. Several generations of ActiGraph are being used; however, little work has been done to verify that measurements are consistent across generations. This study employed mechanical oscillations to characterize the dynamic response and intermonitor variability of three generations of ActiGraph monitors, from the oldest 7164 (n = 13), 71256 (n = 12), to the newest GT1M (n = 12). The response due to independent radius (22.1-60.4 mm) and frequency (25-250 rpm) changes were measured, as well as intermonitor variability within each generation. The 7164 and 71256 have similar relationships between activity counts and radius (P = 0.229) but were significantly different from the GT1M (P < 0.001). The frequency responses were nonlinear in all three generations. Although the response curve shapes were similar, the differences between generations at various frequencies were significant (P < 0.017), especially in the extremes of the measurement range. Intermonitor variability was markedly reduced in the GT1M compared with the 7164 and 71256. Other measurement differences between generations include decreased peak counts and decreased sensitivity in low-frequency detection in the GT1M. The results of this study revealed an improvement of the intermonitor variability by the GT1M monitor. However, the reduced sensitivity in low-count ranges in the GT1M may not be well suited for monitoring sedentary or light-intensity movements. Furthermore, the algorithms for energy expenditure predictions developed using older 7164 monitors may need to be modified for the GT1M.
ActiGraph加速度计是临床和流行病学研究中客观评估身体活动的有用工具。目前正在使用几代ActiGraph；然而，几乎没有开展工作来验证各代产品的测量结果是否一致。本研究采用机械振荡来表征三代ActiGraph监测仪的动态响应和监测仪间的变异性，三代产品分别为最旧的7164（n = 13）、71256（n = 12）以及最新的GT1M（n = 12）。测量了独立半径（22.1 - 60.4毫米）和频率（25 - 250转/分钟）变化引起的响应，以及每一代监测仪之间的变异性。7164和71256在活动计数与半径之间具有相似的关系（P = 0.229），但与GT1M有显著差异（P < 0.001）。三代产品的频率响应均为非线性。尽管响应曲线形状相似，但各代产品在不同频率下的差异显著（P < 0.017），尤其是在测量范围的极值处。与7164和71256相比，GT1M监测仪间的变异性明显降低。各代产品之间的其他测量差异包括GT1M的峰值计数减少以及低频检测灵敏度降低。本研究结果表明GT1M监测仪在监测仪间变异性方面有所改进。然而，GT1M在低计数范围内灵敏度降低可能不太适合监测久坐或低强度运动。此外，使用较旧的7164监测仪开发的能量消耗预测算法可能需要针对GT1M进行修改。
