Validity of Consumer-Based Physical Activity Monitors for Specific Activity Types

PURPOSEConsumer-based physical activity (PA) monitors are popular for individual tracking of PA variables. However, current research has not examined how these monitors track energy expenditure (EE) and steps in distinct activities. This study examined the accuracy of the Fitbits One, Zip, and Flex...

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Bibliographic Details
Published in:Medicine and science in sports and exercise 2016-08, Vol.48 (8), p.1619-1628
Main Authors: NELSON, M BENJAMIN, KAMINSKY, LEONARD A, DICKIN, D CLARK, MONTOYE, ALEXANDER H K
Format: Article
Language:English
Subjects:
Actigraphy - instrumentation
Adolescent
Adult
Aged
Bicycling
Energy Metabolism
Exercise
Female
Fitness Trackers
Humans
Male
Middle Aged
Walking
Young Adult
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Summary:PURPOSEConsumer-based physical activity (PA) monitors are popular for individual tracking of PA variables. However, current research has not examined how these monitors track energy expenditure (EE) and steps in distinct activities. This study examined the accuracy of the Fitbits One, Zip, and Flex and Jawbone UP24 for estimating EE and steps for specific activities and activity categories. METHODSThirty subjects completed a structured protocol consisting of three sedentary, four household, and four ambulatory/exercise activities. All subjects began by lying on a bed for 10 min; 10 other activities were performed for 5 min each. Indirect calorimetry (COSMED) and researcher-counted steps were criterion measures for EE and step counts, respectively. The Omron HJ-720IT pedometer was used as a comparison of step count accuracy. EE and steps were compared with criterion measures using the Friedman repeated-measures nonparametric test and mean absolute percent error (MAPE). RESULTSAll PA monitors predicted EE within 8% of COSMED for sedentary activity but overestimated EE by 16%–40% during ambulatory activity. All monitors except the Fitbit Flex (within 8% of criterion) underestimated EE by 27%–34% during household activity. EE predictions were accompanied with MAPE >10%. For household activity, the Fitbit Flex estimated steps within 10% of researcher-counted steps; all other monitors underestimated steps by 35%–64%. All monitors estimated steps within 4% of researcher-counted steps and displayed MAPE
ISSN:0195-9131
1530-0315
DOI:10.1249/MSS.0000000000000933