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BMC Res Notes. 2017 Apr 20;10(1):161. doi: 10.1186/s13104-017-2476-1.

Physical activity among children: objective measurements using Fitbit One® and ActiGraph.

Author information

1
Department of Nursing Science, University of Turku, 20014, Turku, Finland. lotta.hamari@utu.fi.
2
Turku University Hospital, Kiinamyllynkatu 4-8, 20521, Turku, Finland. lotta.hamari@utu.fi.
3
Department of Information Technology, University of Turku, 20014, Turku, Finland.
4
Paavo Nurmi Centre & Department of Physical Activity and Health, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland.
5
Turku University Hospital, Kiinamyllynkatu 4-8, 20521, Turku, Finland.
6
Turku Centre for Computer Science (TUCS), Department of Information Technologies, Åbo Akademi University, Joukahaisenkatu 3-5 A, 20520, Turku, Finland.
7
Department of Nursing Science, University of Turku, 20014, Turku, Finland.
8
Health and Well-being Unit, Turku University of Applied Sciences, Ruiskatu 8, 20720, Turku, Finland.

Abstract

BACKGROUND:

Self-quantification of health parameters is becoming more popular; thus, the validity of the devices requires assessments. The aim of this study was to evaluate the validity of Fitbit One step counts (Fitbit Inc., San Francisco, CA, USA) against Actigraph wActisleep-BT step counts (ActiGraph, LLC, Pensacola, FL, USA) for measuring habitual physical activity among children.

DESIGN:

The study was implemented as a cross-sectional experimental design in which participants carried two waist-worn activity monitors for five consecutive days.

METHODS:

The participants were chosen with a purposive sampling from three fourth grade classes (9-10 year olds) in two comprehensive schools. Altogether, there were 34 participants in the study. From these, eight participants were excluded from the analysis due to erroneous data. Primary outcome measures for step counts were Fitbit One and Actigraph wActisleep-BT. The supporting outcome measures were based on activity diaries and initial information sheets. Classical Bland-Altman plots were used for reporting the results.

RESULTS:

The average per-participant daily difference between the step counts from the two devices was 1937. The range was [116, 5052]. Fitbit One gave higher step counts for all but the least active participant. According to a Bland-Altman plot, the hourly step counts had a relative large mean bias across participants (161 step counts). The differences were partially explained by activity intensity: higher intensity denoted higher differences, and light intensity denoted lower differences.

CONCLUSIONS:

Fitbit One step counts are comparable to Actigraph step counts in a sample of 9-10-year-old children engaged in habitual physical activity in sedentary and light physical activity intensities. However, in moderate-to-vigorous physical activity, Fitbit One gives higher step counts when compared to Actigraph.

KEYWORDS:

Accelerometer; Children; Investigative techniques; Motor activity; Movement; Physical activity

PMID:
28427441
PMCID:
PMC5397828
DOI:
10.1186/s13104-017-2476-1
[Indexed for MEDLINE]
Free PMC Article

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