Agreement between Fitbit and ActiGraph Estimates of Physical Activity in Young Children. Issue 2 (3rd April 2023)

• Record Type: Journal Article
• Authors: Schmidt, Michael D; Rathbun, Stephen L.; Chu, Zhixuan; Boudreaux, Benjamin D.; Hahn, Lindsay; Novotny, Eric; Johnsen, Kyle; Ahn, Sun Joo (Grace)
• Is Part Of: Measurement in physical education and exercise science. Volume 27:Issue 2(2023)
• Page Start: 171
• Page End: 180
• Publication Date: 2023-04-03
• Subjects: Validity -- fitness trackers -- steps -- change measurement -- youth; Physical fitness -- Testing -- Periodicals; Physical education and training -- Statistical methods -- Periodicals; Physical education and training -- Research -- Periodicals; 613.7
• DOI: 10.1080/1091367X.2022.2125319
• Languages: English
• ISSNs: 1091-367X

Abstract

ABSTRACT: Physical activity (PA) estimates from the Fitbit Flex 2 were compared to those from the ActiGraph GT9X Link in 123 elementary school children. Steps and intensity-specific estimates of PA and 3-month PA change were calculated using two different ActiGraph cut-points (Evenson and Romanzini). Fitbit estimates were 35% higher for steps compared to the ActiGraph. Fitbit and ActiGraph intensity-specific estimates were closest for sedentary and light PA, while estimates of moderate and vigorous PA varied substantially depending upon the ActiGraph cut-points used. Spearman correlations between device estimates were higher for steps ( rs = .70) than for moderate ( rs =.54 to .55) or vigorous ( rs =.29 to .48) PA. There was low concordance between devices in assessing PA changes over time. Agreement between Fitbit Flex 2 and ActiGraph estimates may depend upon the cut-points used to classify PA intensity. However, there is fair to good agreement between devices in ranking children's steps and MVPA.