Institute of Sport and Exercise Science, University of Worcester, Worcester, Worcestershire, UK.
J Hum Kinet. 2012 Mar;31:17-24. doi: 10.2478/v10078-012-0002-z. Epub 2012 Apr 3.
This study aimed to quantify the intra-and inter-instrument reliability of the Actiwatch 4 accelerometer (AW4) in a mechanical setting. Twenty seven AW4 were attached to an isokinetic dynamometer and subjected to angular acceleration for 30 min at 50 deg/sec representing moderate intensity (MPA condition) and 200 deg/sec representing vigorous intensity (VPA condition), with a repeat trial conducted. Reliability was assessed using coefficient of variation (CV), absolute percent error (APE), and intraclass correlation coefficients (ICC). Mean AW4 activity counts displayed acceptable reliability according to CV in both conditions (ConMPA: CVintra = 4.6%, APEintra = 6.6%, CVinter = 6.4%, APEinter = 5.2%; ConVPA: CVintra = 3.9%, APEintra = 5.6%, CVinter = 5.9%, APEinter = 4.7%). When counts were re-categorised into minutes of MPA and VPA, lower CV values were observed (ConMPA: CVintra = 3.2%, APEintra = 4.5%, CVinter = 4.3%, APEinter = 3.2%; ConVPA: CVintra = 0.0%, APEintra = 0.0%, CVinter = 0.0%, APEinter = 0.0%). When activity counts were re-categorised as minutes of MVPA, excellent reliability was observed (CVintra, APEintra, CVinter, and APEinter = 0.0%) in both conditions. Mean AW4 activity counts exhibit reliability statistics comparable to other accelerometers. Reliability is improved when activity counts are re-categorised as time spent in MPA and VPA, with greatest reliability obtained when counts are recategorised as time spent in MVPA. As MVPA is the subcomponent of physical activity most associated with health benefits it would appear that the AW4 is reliable for measuring time spent in this health enhancing intensity category, at least from testing in a mechanical laboratory setting.
本研究旨在量化 Actiwatch 4 加速度计（AW4）在机械环境中的内-间仪器可靠性。将 27 个 AW4 附着在等速测力机上，以 50 度/秒的角速度（代表中等强度（MPA 条件））和 200 度/秒的角速度（代表剧烈强度（VPA 条件））进行 30 分钟的角加速度测试，重复试验。可靠性评估使用变异系数（CV）、绝对百分比误差（APE）和组内相关系数（ICC）。根据 CV，两种条件下 AW4 活动计数的平均值均显示出可接受的可靠性（ConMPA：CVintra=4.6%，APEintra=6.6%，CVinter=6.4%，APEinter=5.2%；ConVPA：CVintra=3.9%，APEintra=5.6%，CVinter=5.9%，APEinter=4.7%）。当计数重新分类为 MPA 和 VPA 分钟时，观察到较低的 CV 值（ConMPA：CVintra=3.2%，APEintra=4.5%，CVinter=4.3%，APEinter=3.2%；ConVPA：CVintra=0.0%，APEintra=0.0%，CVinter=0.0%，APEinter=0.0%）。当活动计数重新分类为 MVPA 分钟时，两种条件下均显示出极好的可靠性（CVintra、APEintra、CVinter 和 APEinter=0.0%）。AW4 的平均活动计数表现出与其他加速度计相当的可靠性统计数据。当活动计数重新分类为 MPA 和 VPA 所花费的时间时，可靠性会提高，当计数重新分类为 MVPA 所花费的时间时，可靠性最高。由于 MVPA 是与健康益处最相关的身体活动的子成分，因此 AW4 似乎可用于测量处于这种有益健康的强度类别的时间，至少从机械实验室测试来看是如此。
