Abstract
This study examined the effects of the ActiGraph’s (AG) low-frequency extension (LFE) filter on steps and physical activity classification in the free-living environment. Thirty-four African-American women (age, 24.5±5.2 years; BMI, 24.9±4.5 kg/m2) had daily activity measured simultaneously with an AG-GT3X+ accelerometer and a New Lifestyles NL-800 pedometer for seven days. Steps per day (steps/day) and time (minutes/day) spent in sedentary, light, and moderate-to-vigorous physical activity (MVPA) were examined with and without the LFE filter (AG-LFE and AG-N, respectively). The AG-LFE recorded more total steps (13,723±4,983 steps/day) compared to AG-N and NL-800 (6,172±2,838 and 5,817±3,037 steps/day, respectively; p<0.001). Compared to the AG-N, the AG-LFE estimated less time in sedentary behaviors (518.7±92.1 vs. 504.2±105.4 min/day, respectively; p<0.001), and more time in light (247.7±70.4 vs. 279.1±74.7 min/day, respectively; p<0.001) and MVPA (18.9±16.9 vs. 21.5±18.2 min/day, respectively; p<0.001), respectively. These data suggest that steps and physical activity classifications will be affected when using the ActiGraph with and without the LFE filter. Future research should investigate the accuracy of these measures using the LFE filter.
Highlights
Accelerometry-based activity monitors are widely used in research for the measurement of physical activity
Similar to previous studies [8, 19, 20], the findings from the current study suggest that the use of the AG-low frequency extension (LFE) filter significantly estimates higher steps/d compared to the AG-N filter and a commonly used pedometer (NL-800)
Even though using the LFE resulted in greater accuracy during treadmill walking, the increased sensitivity provided by the LFE filter resulted in step measurements that were over 30% higher than steps recorded by the StepWatch in a free-living environment
Summary
Accelerometry-based activity monitors are widely used in research for the measurement of physical activity. ActiGraphTM (AG) devices are some of the most common devices used for research purposes, and have been shown to provide accurate estimates of physical activity in the free-living environment [1]. In 2009, AG introduced the low frequency extension (LFE) filter, which increased the device’s sensitivity to lower intensity activities; thereby, allowing for the measurement of a greater range of physical activity intensities [2]. This would hypothetically increase the accuracy of measuring physical activity in participants in the freeliving environment, who may engage in lower intensity activities throughout the day.
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