Background

Commercially available physical activity trackers are very popular in the general population and are increasingly common in clinical and research settings. The marketfor activity trackers are rapidly expanding, requiring them to be validated on an ongoing basis. Different approaches have been used for validating these devices. Studies using treadmills shows good step-counting accuracy although test performed in field tests settings are limited.

Research question

Does step-counting validity differ between a field test and a treadmill protocol for different types of activity trackers?

Methods

Thirty healthy subjects participated in this study, mean age was 28.2 (± 4.33) years, body mass 78.9 (± 12.9) kg, and height 178.5 (± 9.7) cm. A treadmill protocol with three different walking speeds (2, 3 and 4 km/h) and a 982 m field test was used. During the tests, participants’ feet were filmed using a waist-mounted camera. The number of steps were extracted from the video data and used for comparison with four different step counters: a) Polar M200; b) Polar A300; c) Dunlop pedometer; d) Samsung Galaxy S9 smartphone. Validity and agreement determined was determined with the use of Bland-Altman plot and Spearman’s correlation.

Results

Validity was higher for the field test compared to the 4 km/h treadmill test for all tested devices. The smartphone was the most accurate in terms of error, validity and agreement for both the treadmill and field test. All devices performed poorly for the 2 km/h treadmill test and only the smartphone performed well at 3 km/h.

Significance

The results of this study show that step counting validity and error obtained during treadmill walking is not similar to a field test. Future validation studies of activity trackers should consider this when designing a protocol. The smartphone had the lowest mean bias during the field test.

中文翻译：

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在跑步机和地面行走过程中验证不同的踏步计数器。

背景

市售的身体活动追踪器在普通人群中非常流行，并且在临床和研究环境中越来越普遍。活动跟踪器的市场正在迅速扩展，需要对其进行持续验证。已经使用不同的方法来验证这些设备。尽管在现场测试设置中进行的测试受到限制，但使用跑步机进行的研究仍显示出良好的计步精度。

研究问题

对于不同类型的活动跟踪器，现场测试和跑步机协议之间的计步有效性是否有所不同？

方法

30名健康受试者参加了这项研究，平均年龄为28.2（±4.33）岁，体重为78.9（±12.9）kg，身高为178.5（±9.7）cm。使用具有三种不同步行速度（2、3和4 km / h）的跑步机方案，并进行了982 m的现场测试。在测试过程中，参与者的脚是用腰部摄像头拍摄的。从视频数据中提取步数，并与四个不同的步数计数器进行比较：a）Polar M200；b）极地A300; c）邓禄普计步器；d）三星Galaxy S9智能手机。确定的有效性和一致性通过使用布兰德-奥尔特曼图和斯皮尔曼相关性来确定。

结果

与所有测试设备的4 km / h跑步机测试相比，现场测试的有效性更高。就跑步机和现场测试而言，智能手机在错误，有效性和一致性方面是最准确的。在2 km / h的跑步机测试中，所有设备的性能均较差，只有智能手机在3 km / h的条件下表现良好。

意义

这项研究的结果表明，在跑步机行走过程中获得的步数计数有效性和误差与现场测试并不相似。活动跟踪器的未来验证研究在设计协议时应考虑到这一点。在现场测试期间，智能手机的平均偏差最低。