The purpose of this study was to develop a data-driven approach for analyzing incomplete accelerometer data from field-base studies.
Multiple days of accelerometer data from the Stanford Girls health Enrichment Multi-site Studies (N = 294 African American girls) were summed across each minute of each day to produce a composite weekday and weekend day. Composite method estimates of physical activity were compared with those derived from methods typically described in the literature (comparison methods).
The composite method retained 99.7% and 100% of participants in weekday and weekend-day analysis, respectively, versus 84.7% to 94.2% and 28.6% to 99.0% for the comparison methods. Average wearing times for the composite method for weekday and weekend day were 99.6% and 98.6%, respectively, 91.7% to 93.9% and 82.3% to 95.4% for the comparison methods. Composite-method physical activity estimates were similar to comparison-methods estimates.
The composite method used more available accelerometer data than standard approaches, reducing the need to exclude periods within a day, entire days, and participants from analysis.
"The downloaded accelerometry data will be checked to ensure that the number of days of accelerometer data matched the protocol, to ascertain sleep times, and to identify possible RT3 malfunctions . Data will then be scanned for nonworn periods. "
[Show abstract][Hide abstract] ABSTRACT: Activity advice and prescription are commonly used in the management of low back pain (LBP). Although there is evidence for advising patients with LBP to remain active, facilitating both recovery and return to work, to date no research has assessed whether objective measurements of free living physical activity (PA) can predict outcome, recovery and course of LBP.
An observational longitudinal study will investigate PA levels in a cohort of community-dwelling working age adults with acute and sub-acute LBP. Each participant's PA level, functional status, mood, fear avoidance behaviours, and levels of pain, psychological distress and occupational activity will be measured on three occasions during for 1 week periods at baseline, 3 months, and 1 year. Physical activity levels will be measured by self report, RT3 triaxial accelerometer, and activity recall questionnaires. The primary outcome measure of functional recovery will be the Roland Morris Disability Questionnaire (RMDQ). Free living PA levels and changes in functional status will be quantified in order to look at predictive relationships between levels and changes in free living PA and functional recovery in a LBP population.
This research will investigate levels and changes in activity levels of an acute LBP cohort and the predictive relationship to LBP recovery. The results will assess whether occupational, psychological and behavioural factors affect the relationship between free living PA and LBP recovery. Results from this research will help to determine the strength of evidence supporting international guidelines that recommend restoration of normal activity in managing LBP.
[Clinical Trial Registration Number, ACTRN12609000282280].
[Show abstract][Hide abstract] ABSTRACT: This study examines the associations between objectively measured physical activity and cardiovascular disease (CVD) risk factors in preadolescent African American girls.
We conducted a cross-sectional analysis of data from Stanford Girls Health Enrichment Multisite Studies (GEMS) trial. Physical activity was assessed for four days by using an ActiGraph accelerometer and was correlated with anthropometric measures, blood pressure, blood lipids, glucose, and insulin. Associations between physical activity and CVD risk factors were computed using by Spearman correlations. Bonferroni adjustment alpha = .003 was used to correct for multiple testing.
A total of 261 girls participated, of which 208 had complete CVD risk measures (mean age 9.4 years, mean body mass index 20.7 kg/m2). Average daily physical activity and time spent in moderate-to-vigorous physical activity (MVPA) were significantly correlated with body mass index (r = -.23, P=.0008 and r = -.29, P<.0001, respectively) and insulin (r = -.27, P=.0001 and r = -.30, P<.0001, respectively) but not to other CVD factors. After adjusting for age-adjusted pubertal stage of development, the association between MVPA and insulin remained significant.
Objective measures of both average daily physical activity and MVPA were inversely associated with body mass index and insulin levels in African American girls.
[Show abstract][Hide abstract] ABSTRACT: This paper reviews the evidence behind the methodological decisions accelerometer users make when assessing habitual physical activity in children aged 0-5 years. The purpose of the review is to outline an evidence-guided protocol for using accelerometry in young children and to identify gaps in the evidence base where further investigation is required. Studies evaluating accelerometry methodologies in young children were reviewed in two age groups (0-2 years and 3-5 years) to examine: (i) which accelerometer should be used, (ii) where the accelerometer should be placed, (iii) which epoch should be used, (iv) how many days of monitoring are required, (v) how many minutes of monitoring per day are required, (vi) how data should be reduced, (vii) which cut-point definitions for identifying activity intensity should be used, and (viii) which physical activity outcomes should be reported and how. Critique of the available evidence provided a basis for the development of a recommended users protocol in 3-5-year olds, although several issues require further research. Because of the absence of methodological studies in children under 3 years, a protocol for the use of accelerometers in this age range could not be specified. Formative studies examining the utility, feasibility and validity of accelerometer-based physical activity assessments are required in children under 3 years of age. Recommendations for further research are outlined, based on the above findings, which, if undertaken, will enhance the accuracy of accelerometer-based assessments of habitual physical activity in young children.
Journal of Science and Medicine in Sport 02/2009; 12(5):557-67. DOI:10.1016/j.jsams.2008.10.008 · 3.19 Impact Factor
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