Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium.
JMIR Mhealth Uhealth. 2020 May 19;8(5):e16674. doi: 10.2196/16674.
Wearable trackers for monitoring physical activity (PA) and total sleep time (TST) are increasingly popular. These devices are used not only by consumers to monitor their behavior but also by researchers to track the behavior of large samples and by health professionals to implement interventions aimed at health promotion and to remotely monitor patients. However, high costs and accuracy concerns may be barriers to widespread adoption.
This study aimed to investigate the concurrent validity of 6 low-cost activity trackers for measuring steps, moderate-to-vigorous physical activity (MVPA), and TST: Geonaut On Coach, iWown i5 Plus, MyKronoz ZeFit4, Nokia GO, VeryFit 2.0, and Xiaomi MiBand 2.
A free-living protocol was used in which 20 adults engaged in their usual daily activities and sleep. For 3 days and 3 nights, they simultaneously wore a low-cost tracker and a high-cost tracker (Fitbit Charge HR) on the nondominant wrist. Participants wore an ActiGraph GT3X+ accelerometer on the hip at daytime and a BodyMedia SenseWear device on the nondominant upper arm at nighttime. Validity was assessed by comparing each tracker with the ActiGraph GT3X+ and BodyMedia SenseWear using mean absolute percentage error scores, correlations, and Bland-Altman plots in IBM SPSS 24.0.
Large variations were shown between trackers. Low-cost trackers showed moderate-to-strong correlations (Spearman r=0.53-0.91) and low-to-good agreement (intraclass correlation coefficient [ICC]=0.51-0.90) for measuring steps. Weak-to-moderate correlations (Spearman r=0.24-0.56) and low agreement (ICC=0.18-0.56) were shown for measuring MVPA. For measuring TST, the low-cost trackers showed weak-to-strong correlations (Spearman r=0.04-0.73) and low agreement (ICC=0.05-0.52). The Bland-Altman plot revealed a variation between overcounting and undercounting for measuring steps, MVPA, and TST, depending on the used low-cost tracker. None of the trackers, including Fitbit (a high-cost tracker), showed high validity to measure MVPA.
This study was the first to examine the concurrent validity of low-cost trackers. Validity was strongest for the measurement of steps; there was evidence of validity for measurement of sleep in some trackers, and validity for measurement of MVPA time was weak throughout all devices. Validity ranged between devices, with Xiaomi having the highest validity for measurement of steps and VeryFit performing relatively strong across both sleep and steps domains. Low-cost trackers hold promise for monitoring and measurement of movement and sleep behaviors, both for consumers and researchers.
可穿戴式追踪器用于监测身体活动（PA）和总睡眠时间（TST）越来越受欢迎。这些设备不仅被消费者用于监测自己的行为，也被研究人员用于追踪大样本的行为，以及被健康专业人员用于实施旨在促进健康的干预措施，并远程监测患者。然而，高成本和准确性问题可能是广泛采用的障碍。
本研究旨在调查 6 种低成本活动追踪器测量步数、中高强度体力活动（MVPA）和 TST 的同时效度：Geonaut On Coach、iWown i5 Plus、MyKronoz ZeFit4、Nokia GO、VeryFit 2.0 和小米手环 2。
使用自由生活协议，20 名成年人进行了日常活动和睡眠。连续 3 天 3 夜，他们同时将低成本追踪器和高成本追踪器（Fitbit Charge HR）佩戴在非优势手腕上。参与者在白天佩戴 ActiGraph GT3X+加速度计，在夜间佩戴 BodyMedia SenseWear 设备在非优势的上臂上。使用 IBM SPSS 24.0 中的平均绝对百分比误差评分、相关性和 Bland-Altman 图，将每个追踪器与 ActiGraph GT3X+和 BodyMedia SenseWear 进行比较，评估效度。
追踪器之间存在较大差异。低成本追踪器在测量步数方面表现出中度到高度的相关性（Spearman r=0.53-0.91）和低到良好的一致性（组内相关系数[ICC]=0.51-0.90）。在测量 MVPA 方面，相关性较弱到中度（Spearman r=0.24-0.56），一致性较低（ICC=0.18-0.56）。在测量 TST 方面，低成本追踪器显示出弱到中度的相关性（Spearman r=0.04-0.73）和低一致性（ICC=0.05-0.52）。Bland-Altman 图显示，根据使用的低成本追踪器，在测量步数、MVPA 和 TST 时，存在计数过多和过少的变化。没有一个追踪器，包括 Fitbit（一种高成本追踪器），显示出测量 MVPA 的高有效性。
本研究首次检查了低成本追踪器的同时效度。在测量步数方面的有效性最强；在一些追踪器中，有证据表明对睡眠的测量具有有效性，而在所有设备中，对 MVPA 时间的测量有效性较弱。设备之间的有效性存在差异，小米在测量步数方面的有效性最高，而 VeryFit 在睡眠和步数两个领域的表现都相对较强。低成本追踪器在监测和测量运动和睡眠行为方面具有潜力，无论是对消费者还是研究人员而言。
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