Rowlands Alex V, Olds Tim S, Bakrania Kishan, Stanley Rebecca M, Parfitt Gaynor, Eston Roger G, Yates Thomas, Fraysse François
Diabetes Research Centre, University of Leicester, Leicester Diabetes Centre, Leicester General Hospital, United Kingdom; National Institute for Health Research (NIHR) Leicester-Loughborough Diet, Lifestyle and Physical Activity Biomedical Research Unit (BRU), Leicester Diabetes Centre, Leicester General Hospital, United Kingdom; Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Australia.
Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Australia.
J Sci Med Sport. 2017 Apr;20(4):368-372. doi: 10.1016/j.jsams.2016.04.013. Epub 2016 May 21.
Choice of accelerometer wear-site may facilitate greater compliance in research studies. We aimed to test whether a simple method could automatically discriminate whether an accelerometer was worn on the hip or wrist from free-living data.
Cross-sectional.
Twenty-two 10-12y old children wore a GENEActiv at the wrist and at the hip for 7-days. The angle between the forearm and the total acceleration vector for the wrist-worn monitor and between the pelvis and the total acceleration vector for the hip-worn monitor (i.e. the angle between the Y-axis component of the acceleration and the total acceleration vector) was calculated for each 5s epoch. The standard deviation of this angle (SDangle) was calculated over time for the wrist-worn and hip-worn monitor for windows of varying lengths. We hypothesised that the wrist angle would be more variable than the hip angle.
Wear site could be discriminated based on SDangle; the shorter the time window the lower the optimal threshold and Area under the Receiver-Operating-Characteristic curve (AUROC) for discrimination of wear-site (AUROC=0.833 (1min) - 0.952 (12h)). Classification accuracy was good for windows of 8min (sensitivity=90%, specificity=87%, AUROC=0.92) and plateaued for windows of ≥60min (sensitivity and specificity >90%, AUROC=0.95-0.96).
We have presented a robust, computationally simple method that detects whether an accelerometer is being worn on the hip or wrist from 8 to 60min of data. This facilitates the use of wear-site specific algorithms to analyse accelerometer data.
选择加速度计的佩戴部位可能有助于提高研究中的依从性。我们旨在测试一种简单的方法能否根据日常活动数据自动区分加速度计是佩戴在髋部还是腕部。
横断面研究。
22名10至12岁的儿童在腕部和髋部分别佩戴GENEActiv加速度计7天。计算腕部佩戴监测器时前臂与总加速度向量之间的角度，以及髋部佩戴监测器时骨盆与总加速度向量之间的角度（即加速度的Y轴分量与总加速度向量之间的角度），每5秒一个时间段。计算不同时长窗口内腕部和髋部佩戴监测器的该角度标准差（SDangle）随时间的变化。我们假设腕部角度比髋部角度变化更大。
可根据SDangle区分佩戴部位；时间窗口越短，区分佩戴部位的最佳阈值和受试者工作特征曲线下面积（AUROC）越低（AUROC = 0.833（1分钟） - 0.952（12小时））。8分钟窗口的分类准确率良好（灵敏度 = 90%，特异性 = 87%，AUROC = 0.92），60分钟及以上窗口的准确率趋于平稳（灵敏度和特异性 > 90%，AUROC = 0.95 - 0.96）。
我们提出了一种强大且计算简单的方法，可根据8至60分钟的数据检测加速度计是佩戴在髋部还是腕部。这有助于使用针对佩戴部位的特定算法来分析加速度计数据。
