Christine A. Schaefer

Accuracy of self-reported height and weight in children aged 6 to 11 years.

The purpose of this study was to determine the ability of first-, third-, and fifth-graders to accurately self-report height and weight. Self-reported and measured values for height and weight were recorded for 487 students. The ability to self-report a reasonable value for height and weight improved with grade level, but children in all 3 grade levels significantly underreported their height and weight. Only fifth-graders accurately self-reported their weight; therefore, using self-reported height and weight to determine the prevalence of overweight and obesity for elementary school–aged children is not recommended.

Establishing and evaluating wrist cutpoints for the GENEActiv accelerometer in youth.

PURPOSE This study aimed to establish physical activity (PA) intensity cutpoints for a wrist-mounted GENEActiv accelerometer (ACC) in elementary school-age children. A second purpose was to apply cutpoints to a free-living sample and examine the duration of PA based on continuous 1-s epochs. METHODS Metabolic and ACC data were collected during nine typical activities in 24 children age 6-11 yr. Measured VO2 values were divided by Schofield-estimated resting values to determine METs. ACC data were collected at 75 Hz, band pass filtered, and averaged over each 1-s interval. Receiver operator characteristic curves were used to establish cutpoints at sedentary (≤ 1.5 METs), light (1.6-2.99 METs), moderate (3.0-5.99 METs), and vigorous (≥ 6 METs) activities. These cutpoints were applied to a free-living independent data set to quantify the amount of moderate-vigorous PA (MVPA) and to examine how bout length (1, 2, 3, 5, 10, 15, and 60 s) affected the accumulation of MVPA. RESULTS Receiver operator characteristic yielded areas under the curve of 0.956, 0.946, and 0.940 for sedentary, moderate, and vigorous intensities, respectively. Cutpoints for sedentary, moderate, and vigorous intensities were 0.190 g, 0.314 g, and 0.998 g, respectively. Intensity classification accuracies ranged from 27.6% (light) to 88.7% (vigorous) when cutpoints were applied to the calibration data. When applied to free-living data (n = 47 children age 6-11 yr), estimated daily MVPA was 308 min and decreased to 14.3 min when only including 1-min periods of continuous MVPA. CONCLUSIONS Cutpoints that quantify movements associated with moderate-vigorous intensity, when applied to a laboratory protocol, result in large amounts of accumulated MVPA using the 1-s epoch compared to prior studies, highlighting the need for representative calibration activities and free-living validation of cutpoints and epoch length selection.

Establishing Wrist-Based Cutpoints for the Actical Accelerometer in Elementary School-Aged Children

BACKGROUND The wrist has become a standard location for accelerometry (ACC) data collection, primarily to optimize compliance, yet interpretation of wrist ACC data is limited due to a lack of calibration studies. This study aimed to establish cutpoints for a wrist-mounted Actical accelerometer in 6- to 11-year-old children using 2 methods. METHODS Metabolic and ACC data (15-sec epoch) were collected during 8 activities in 22 children ages 6-11. Linear regression (LR) and Receiver Operator Characteristics (ROC) were used to examine the relationship between METs and ACC counts. Cutpoints were established at < 1.5, 1.5-2.99, 3-5.99, and ≥ 6 METs for sedentary, light, moderate, and vigorous activity, respectively. Cutpoints were applied to a large, multiday sample of children (n = 269) to examine differences in cutpoints on minutes of moderate to vigorous PA (MVPA). RESULTS LR and ROC yielded moderate cutpoints of 574 and 388, respectively. When applied to the large sample, LR and ROC cutpoints resulted in an estimated 83 and 140 minutes of daily MVPA, respectively. CONCLUSIONS This study established wrist-mounted Actical cutpoints for children using 2 methods. The differences in cutpoints and their effect on estimates of MVPA in an independent sample highlight challenges associated with establishing cutpoints, suggesting that standardized calibration procedures be developed.

Changes in physical activity and sedentary behavior in a randomized trial of an internet-based versus workbook-based family intervention study.

BACKGROUND The America on the Move (AOM) Family Intervention Program has been shown to prevent excess weight gain in overweight children. Providing intervention materials via the internet would have the potential to reach more families but may increase sedentary behavior. The purpose was to evaluate whether delivering the AOM Family Intervention via the internet versus printed workbook would have a similar impact on sedentary behaviors in children. METHODS 131 children (age 8-12) were randomized to receive the AOM Family Intervention via the internet or workbook for 12 weeks. Changes in objectively measured sedentary time and moderate-to vigorous physical activity (MVPA) as well as self-reported screen time were compared between groups. RESULTS There were no significant differences between groups in screen time, sedentary time, or MVPA at the end of the 12 week intervention. Families receiving the intervention via the internet were more likely to remain in the study (98% vs. 82%, P = .016). CONCLUSIONS Using the internet to deliver the lifestyle intervention did not increase sedentary behavior in children. Attrition rates were lower when the program was delivered by internet versus via printed materials. These results provide support for using the internet to deliver healthy lifestyle programs for children.

Recess environment and curriculum intervention on children’s physical activity: IPLAY

Understanding the impacts of the built environment on physical activity (PA) is essential to promoting childrens PA. The purpose of this study was to investigate the effects of schoolyard renovations and a PA recess curriculum alone and in combination on childrens PA. This was a 2 (learning landscape [LL] vs. non-LL) × 2 (curriculum intervention vs. no curriculum intervention) factorial design with random assignment to the curriculum intervention, and six elementary schools per condition. PA outcomes were assessed preprogram, mid-program, immediate postprogram, and one year postprogram. No meaningful intervention effects were found. Lack of an effect may be due to the brief dose of recess, the curriculum not being integrated within the schoolyard, the LL implementation occurring prior to the study, or the already high levels of PA. Potential avenues to promote PA include making recess longer, integrating recess into the school curricula, and developing recess PA curricula integrating schoolyards.