Effects of Frequency Filtering on Intensity and Noise in Accelerometer-Based Physical Activity Measurements
Effects of Frequency Filtering on Intensity and Noise in Accelerometer-Based Physical Activity Measurements
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DOI：
10.3390/s19092186
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发表时间：
2019-05-01
期刊：
影响因子：
3.9
通讯作者：
Arvidsson, Daniel
中科院分区：
文献类型：
--
作者：
Fridolfsson, Jonatan;Borjesson, Mats;Arvidsson, Daniel
在客观身体活动（PA）测量中，在处理加速度计数据时，应用比最常用的ActiGraph（AG）滤波器更宽的频率滤波器可能是有益的。然而，以前没有研究过更宽的滤波器对噪声的脆弱性。本研究探讨了较宽频率滤波器对PA测量、久坐行为（SED）和噪声捕获的影响。除标准AG带通滤波器（0.29-1.63 Hz）外，还分析了在4 Hz、10 Hz或移除低通分量截止的修改滤波器。使用儿童和成人的实验室数据对能量消耗进行校准，以生成过滤器特定强度临界点。使用不同的滤波器和强度截止点处理来自儿童和成人的自由生活加速度计数据。在高达10 Hz的频率下，与PA相关的加速度有贡献。贡献是更明显的，在中度和剧烈PA水平，虽然额外的加速也发生在SED。AG和更宽的过滤器之间的分类差异在SED（1-2%）时很小，但在最高强度（>90%）时非常大。本研究提出了一个最佳的低通频率滤波器，截止频率为10 Hz，包括所有与PA相关的加速度，噪声影响最小。
In objective physical activity (PA) measurements, applying wider frequency filters than the most commonly used ActiGraph (AG) filter may be beneficial when processing accelerometry data. However, the vulnerability of wider filters to noise has not been investigated previously. This study explored the effect of wider frequency filters on measurements of PA, sedentary behavior (SED), and capturing of noise. Apart from the standard AG band-pass filter (0.29-1.63 Hz), modified filters with low-pass component cutoffs at 4 Hz, 10 Hz, or removed were analyzed. Calibrations against energy expenditure were performed with lab data from children and adults to generate filter-specific intensity cut-points. Free-living accelerometer data from children and adults were processed using the different filters and intensity cut-points. There was a contribution of acceleration related to PA at frequencies up to 10 Hz. The contribution was more pronounced at moderate and vigorous PA levels, although additional acceleration also occurred at SED. The classification discrepancy between AG and the wider filters was small at SED (1-2%) but very large at the highest intensities (>90%). The present study suggests an optimal low-pass frequency filter with a cutoff at 10 Hz to include all acceleration relevant to PA with minimal effect of noise.