Estimating physical activity from incomplete accelerometer data in field studies.
ABSTRACT 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.
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ABSTRACT: IMPORTANCE Identifying community-based programs that increase physical activity among diverse youth could yield sustainable tools to reduce obesity and obesity disparities. OBJECTIVE To evaluate the impact of a community-based after-school soccer and youth development program, America SCORES, on students' physical activity, weight status, and fitness. DESIGN Cluster-randomized trial. Study measures were collected in the fall (baseline), winter (midpoint), and spring (end point) of the 2009-2010 school year. SETTING After-school programs in 6 schools within a large urban school district. PARTICIPANTS All 4th and 5th grade students in after-school programs at the study schools were eligible. INTERVENTION Three schools were randomized to receive the SCORES after-school program, delivered via the train-the-trainer model. MAIN OUTCOME MEASURES Change in minutes of after-school moderate-to-vigorous physical activity (MVPA), fitness (maximal oxygen consumption), and body mass index over 1 school year. RESULTS Participants (n = 156) were diverse (42% Latino, 32% Asian, and 12% African American) and 76 (49%) had a body mass index at or above the 85th percentile. There were no significant group differences in the change in physical activity, fitness, or weight status among all students. However, among students with a body mass index at or above the 85th percentile, SCORES significantly increased MVPA after school (3.4 min/d; 95% CI, 0.3-6.5) and on Saturdays (18.5 minutes; 95% CI, 3.4-33.6). CONCLUSIONS AND RELEVANCE Existing community-based programs such as SCORES can increase physical activity among low-income youth, particularly those most at risk for weight-related comorbidities. While evaluating existing programs presents special challenges, partnerships between communities, schools, and researchers are an important component of translational research to address obesity. TRIAL REGISTRATION clinicaltrials.gov Identifier:NCT01156103.02/2013; 167(4):1-6. DOI:10.1001/jamapediatrics.2013.1071
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ABSTRACT: BACKGROUND: The after-school period is potentially an important venue for increasing physical activity for youth. We sought to assess the effectiveness of the Sports, Play, and Recreation for Youth (SPARK) program to increase physical activity and improve cardiorespiratory fitness and weight status among elementary students after school. METHODS: This quasi-experimental controlled study compared change in moderate to vigorous physical activity (MVPA), body mass index (BMI) z-score, and cardiorespiratory fitness (VO(2) ) over 5 months between students in after-school programs exposed to SPARK versus controls. Participants were fifth grade students at 3 intervention schools (N = 48) and 3 control schools (N = 52). RESULTS: There was no difference between groups in mean change in MVPA, BMI z-score, or cardiorespiratory fitness. After-school time dedicated to physical activity did not increase with the implementation of SPARK. Intervention students' self-assessment of their activity levels relative to their peers significantly increased compared to control students (p = .011). CONCLUSIONS: In this 5-month study, the SPARK program did not increase MVPA in the after-school setting. Increasing the amount of time dedicated to physical activity may be as important as the curriculum used to effectively increase physical activity after school.Journal of School Health 10/2012; 82(10):457-461. DOI:10.1111/j.1746-1561.2012.00722.x · 1.50 Impact Factor
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ABSTRACT: In the evaluation of childhood obesity interventions, few researchers undertake a rigorous feasibility stage in which the design and procedures of the evaluation process are examined. Consequently, phase III studies often demonstrate methodological weaknesses. Our aim was to conduct a feasibility trial of the evaluation of WATCH IT, a community obesity intervention for children and adolescents. We sought to determine an achievable recruitment rate; acceptability of randomisation, assessment procedures, and dropout rate; optimal outcome measures for the definitive trial; and a robust sample size calculation. Our goal was to recruit 70 participants over 6 months, randomise them to intervention or control group, and retain participation for 12 months. Assessments were taken prior to randomisation and after 6 and 12 months. Procedures mirrored those intended for a full-scale trial, but multiple measures of similar outcomes were included as a means to determine those most appropriate for future research. Acceptability of the research and impact of the research on the programme were ascertained through interviewing participants and staff. We recruited 70 participants and found that randomisation and data collection procedures were acceptable. Self-referral (via media promotion) was more effective than professional referral. Blinding of assessors was sustained to a reasonable degree, and optimal outcome measures for a full-scale trial were identified. Estimated sample size was significantly greater than sample sized reported in published trials. There was some negative impact on the existing programme as a result of the research, a lesson for designers of future trials. We successfully recruited socially disadvantaged families, but the majority of families were of White British nationality. The composition of the participants was an added valuable lesson, suggesting that recruitment strategies to obtain a more heterogeneous ethnic sample warrant consideration in future research. This study provided us with confidence that we can run a phase III multi-centre trial to test the effectiveness of WATCH IT. Importantly, it was invaluable in informing the design not only of that trial but also of future evaluations of childhood obesity treatment interventions.Clinical Trials 12/2011; 8(6):755-64. DOI:10.1177/1740774511424766 · 1.94 Impact Factor