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Validation And Accuracy Of Fitbit Charge: A Pilot Study In A University Worksite Walking Program362 Board #199 June 1, 1100 AM - 1230 PM

Leininger, Lisa J.; Cook, Brian J.; Jones, Veronica; Bellumori, Maria; Adams, Kent J. FACSM

Medicine & Science in Sports & Exercise: May 2016 - Volume 48 - Issue 5S - p 96
doi: 10.1249/01.mss.0000485293.86436.f1
A-46 Free Communication/Poster - Fitness Assessment Wednesday, June 1, 2016, 7:30 AM - 12:30 PM Room: Exhibit Hall A/B

California State University, Monterey Bay, Seaside, CA. (Sponsor: Kent J. Adams, FACSM)

Email: lleininger@csumb.edu

(No relationships reported)

PURPOSE: Wearable activity monitors (e.g., Fitbit®) have become increasingly popular for both researchers and lay people alike. Recent studies have reported several Fitbit® models correlate with research grade monitors; however none to date have examined the Fitbit® Charge model. Furthermore, none have reported on the accuracy of Fitbit® devices. The primary purpose of this study was to compare step counts assessed by Fitbit® Charge and a research grade accelerometer (i.e., Actigraph®). The secondary purpose of this study was to compare the Fitbit® Charge algorithms for physical activity intensity with an algorithm validated for research purposes.

METHODS: Participants (n=8) wore Fitbit® Charge and Actigraph® monitors for 7 days. First, correlations were run to examine the concordance of step counts and physical activity intensity levels derived from Fitbit® Charge and Actigraph® algorithms. Next, accuracy was investigated by paired sample t-tests comparing each device’s assessment of step counts and minutes spent in light, moderate and vigorous intensity activity.

RESULTS: Significant correlations were found for all study outcomes (p’s < .05). Significant differences were observed for step counts on all days and weekly total step count (p’s < .05). Analyses of each intensity level revealed significant differences on most days for light and moderate intensity (p’s <.05). For vigorous intensity, only day 6 (p = .007) and accumulated weekly total of minutes were different (p = .014).

CONCLUSIONS: Our correlation results were similar to previous research examining validity of other Fitbit® models. However, Fitbit® Charge devices may overestimate step counts. Moreover, the algorithm used by Fitbit® may overestimate light and vigorous physical activity, while underestimating minutes in moderate physical activity. Further research is needed to determine reliability of Fitbit® Charge to assess activity and intensity that reflects current health recommendations. Therefore, researchers should use discretion if considering use of Fitbit® Charge for research purposes.

© 2016 American College of Sports Medicine