Journal article
How Accurate Is Your Activity Tracker? A Comparative Study of Step Counts in Low-Intensity Physical Activities
JMIR mHealth and uHealth, Vol.5(8), pp.e106-e106
08/11/2017
Handle:
https://hdl.handle.net/2376/109430
PMCID: PMC5572056
PMID: 28801304
Abstract
As commercially available activity trackers are being utilized in clinical trials, the research community remains uncertain about reliability of the trackers, particularly in studies that involve walking aids and low-intensity activities. While these trackers have been tested for reliability during walking and running activities, there has been limited research on validating them during low-intensity activities and walking with assistive tools.
The aim of this study was to (1) determine the accuracy of 3 Fitbit devices (ie, Zip, One, and Flex) at different wearing positions (ie, pants pocket, chest, and wrist) during walking at 3 different speeds, 2.5, 5, and 8 km/h, performed by healthy adults on a treadmill; (2) determine the accuracy of the mentioned trackers worn at different sites during activities of daily living; and (3) examine whether intensity of physical activity (PA) impacts the choice of optimal wearing site of the tracker.
We recruited 15 healthy young adults to perform 6 PAs while wearing 3 Fitbit devices (ie, Zip, One, and Flex) on their chest, pants pocket, and wrist. The activities include walking at 2.5, 5, and 8 km/h, pushing a shopping cart, walking with aid of a walker, and eating while sitting. We compared the number of steps counted by each tracker with gold standard numbers. We performed multiple statistical analyses to compute descriptive statistics (ie, ANOVA test), intraclass correlation coefficient (ICC), mean absolute error rate, and correlation by comparing the tracker-recorded data with that of the gold standard.
All the 3 trackers demonstrated good-to-excellent (ICC>0.75) correlation with the gold standard step counts during treadmill experiments. The correlation was poor (ICC<0.60), and the error rate was significantly higher in walker experiment compared to other activities. There was no significant difference between the trackers and the gold standard in the shopping cart experiment. The wrist worn tracker, Flex, counted several steps when eating (P<.01). The chest tracker was identified as the most promising site to capture steps in more intense activities, while the wrist was the optimal wearing site in less intense activities.
This feasibility study focused on 6 PAs and demonstrated that Fitbit trackers were most accurate when walking on a treadmill and least accurate during walking with a walking aid and for low-intensity activities. This may suggest excluding participants with assistive devices from studies that focus on PA interventions using commercially available trackers. This study also indicates that the wearing site of the tracker is an important factor impacting the accuracy performance. A larger scale study with a more diverse population, various activity tracker vendors, and a larger activity set are warranted to generalize our results.
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Details
- Title
- How Accurate Is Your Activity Tracker? A Comparative Study of Step Counts in Low-Intensity Physical Activities
- Creators
- Parastoo Alinia - School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA, United StatesChris Cain - School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA, United StatesRamin Fallahzadeh - School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA, United StatesArmin Shahrokni - Geriatrics / Gastrointestinal Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, NY, United StatesDiane Cook - School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA, United StatesHassan Ghasemzadeh - School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA, United States
- Publication Details
- JMIR mHealth and uHealth, Vol.5(8), pp.e106-e106
- Academic Unit
- Electrical Engineering and Computer Science, School of
- Publisher
- Canada
- Identifiers
- 99900547147001842
- Language
- English
- Resource Type
- Journal article