Validity and reliability of fitbit flex for step count, moderate to vigorous physical activity and activity energy expenditure

Objectives: To examine the validity and reliability of the Fitbit Flex against direct observation for measuring steps in the laboratory and against the Actigraph for step counts in free-living conditions and for moderate-to-vigorous physical activity (MVPA) and activity energy expenditure (AEE) overall. Methods: Twenty-five adults (12 females, 13 males) wore a Fitbit Flex and an Actigraph GT3X+ during a laboratory based protocol (including walking, incline walking, running and stepping) and free-living conditions during a single day period to examine measurement of steps, AEE and MVPA. Twenty-four of the participants attended a second session using the same protocol. Results: Intraclass correlations (ICC) for test-retest reliability of the Fitbit Flex were strong for walking (ICC = 0.57), moderate for stair stepping (ICC = 0.34), and weak for incline walking (ICC = 0.22) and jogging (ICC = 0.26). The Fitbit significantly undercounted walking steps in the laboratory (absolute proportional difference: 21.2%, 95%CI 13.0-29.4%), but it was more accurate, despite slightly over counting, for both jogging (6.4%, 95%CI 3.7-9.0%) and stair stepping (15.5%, 95%CI 10.1-20.9%). The Fitbit had higher coefficients of variation (Cv) for step counts compared to direct observation and the Actigraph. In free-living conditions, the average MVPA minutes were lower in the Fitbit (35.4 minutes) compared to the Actigraph (54.6 minutes), but AEE was greater from the Fitbit (808.1 calories) versus the Actigraph (538.9 calories). The coefficients of variation were similar for AEE for the Actigraph (Cv = 36.0) and Fitbit (Cv = 35.0), but lower in the Actigraph (Cv = 25.5) for MVPA against the Fitbit (Cv = 32.7). Conclusion: The Fitbit Flex has moderate validity for measuring physical activity relative to direct observation and the Actigraph. Test-rest reliability of the Fitbit was dependant on activity type and had greater variation between sessions compared to the Actigraph. Physical activity surveillance studies using the Fitbit Flex should consider the potential effect of measurement reactivity and undercounting of steps

Alexithymia in juvenile primary headache sufferers: a pilot study

Starting in the 1990s, there has been accumulating evidence of alexithymic characteristics in adult patients with primary headache. Little research has been conducted, however, on the relationship between alexithymia and primary headache in developmental age. In their research on alexithymia in the formative years, the authors identified one of the most promising prospects for research, as discussed here. The aim of this study was to verify whether there is: (a) a link between tension-type headache and alexithymia in childhood and early adolescence; and (b) a correlation between alexithymia in children/preadolescents and their mothers. This study was based on an experimental group of 32 patients (26 females and 6 males, aged from 8 to 15 years, mean 11.2 ± 2.0) suffering from tension-type headache and 32 control subjects (26 females and 6 males, aged from 8 to 15 years, mean 11.8 ± 1.6). Tension-type headache was diagnosed by applying the International Headache Classification (ICHD-II, 2004). The alexithymic construct was measured using an Italian version of the Alexithymia Questionnaire for Children in the case of the juvenile patients and the Toronto Alexithymia Scale (TAS-20) for their mothers. Higher rates of alexithymia were observed in the children/preadolescents in the experimental group (EG) than in the control group; in the EG there was no significant correlation between the alexithymia rates in the children/preadolescents and in their mothers

Validation of the Fitbit Zip for monitoring physical activity among free-living adolescents

BACKGROUND: The widespread availability of affordable consumer-oriented devices for monitoring physical activity offers an appealing option to physical activity researchers, but studies are needed to demonstrate the validity and reliability of these products. To examine the validity of the Fitbit Zip, we recruited three cohorts (N’s = 25, 35, and 27) of middle-school students to wear the Fitbit and the ActiGraph simultaneously for a week. Adolescents were healthy volunteers representing a range of activity levels. Mean daily minutes of MVPA and mean steps per day were compared between the Fitbit Zip and the Actigraph. RESULTS: The step data for the Fitbit Zip correlated highly with the step data yielded by the ActiGraph (r’s = .72, .92, .96), and the MVPA data for the Fitbit Zip correlated highly with the MVPA data from the ActiGraph (r’s = .67, .79, .94). Bland–Altman plots revealed that the Fitbit Zip overestimated activity in comparison to the ActiGraph, especially for Cohort One, which completed the study before Fitbit modified their algorithms to count as activity only bouts that continued for at least 10 min. CONCLUSIONS: Our data suggest that the Fitbit Zip is a reasonable alternative to the ActiGraph for estimating activity among free-living adolescents. However, data from the Fitbit should not be used interchangeably with data from the ActiGraph, as there is a consistent tendency for the Fitbit to overestimate steps in comparison to the ActiGraph. Also, the findings confirm concern about using for research a consumer-oriented device that does not make public their algorithms

Governance modes, policy regimes and operational plans: A multi-level nested model of policy instrument choice and policy design

Public policy, Policy tools, Governing instruments, Policy design,