Rebecca W. Moore

Comparison of accelerometer cut points for predicting activity intensity in youth.

UNLABELLED The absence of comparative validity studies has prevented researchers from reaching consensus regarding the application of intensity-related accelerometer cut points for children and adolescents. PURPOSE This study aimed to evaluate the classification accuracy of five sets of independently developed ActiGraph cut points using energy expenditure, measured by indirect calorimetry, as a criterion reference standard. METHODS A total of 206 participants between the ages of 5 and 15 yr completed 12 standardized activity trials. Trials consisted of sedentary activities (lying down, writing, computer game), lifestyle activities (sweeping, laundry, throw and catch, aerobics, basketball), and ambulatory activities (comfortable walk, brisk walk, brisk treadmill walk, running). During each trial, participants wore an ActiGraph GT1M, and V˙O2 was measured breath-by-breath using the Oxycon Mobile portable metabolic system. Physical activity intensity was estimated using five independently developed cut points: Freedson/Trost (FT), Puyau (PU), Treuth (TR), Mattocks (MT), and Evenson (EV). Classification accuracy was evaluated via weighted κ statistics and area under the receiver operating characteristic curve (ROC-AUC). RESULTS Across all four intensity levels, the EV (κ=0.68) and FT (κ=0.66) cut points exhibited significantly better agreement than TR (κ=0.62), MT (κ=0.54), and PU (κ=0.36). The EV and FT cut points exhibited significantly better classification accuracy for moderate- to vigorous-intensity physical activity (ROC-AUC=0.90) than TR, PU, or MT cut points (ROC-AUC=0.77-0.85). Only the EV cut points provided acceptable classification accuracy for all four levels of physical activity intensity and performed well among children of all ages. The widely applied sedentary cut point of 100 counts per minute exhibited excellent classification accuracy (ROC-AUC=0.90). CONCLUSIONS On the basis of these findings, we recommend that researchers use the EV ActiGraph cut points to estimate time spent in sedentary, light-, moderate-, and vigorous-intensity activity in children and adolescents.

Reporting accelerometer methods in physical activity intervention studies: a systematic review and recommendations for authors.

Objective This systematic review assessed the completeness of accelerometer reporting in physical activity (PA) intervention studies and assessed factors related to accelerometer reporting. Design The PubMed database was used to identify manuscripts for inclusion. Included studies were PA interventions that used accelerometers, were written in English and were conducted between 1 January 1998 and 31 July 2014. 195 manuscripts from PA interventions that used accelerometers to measure PA were included. Manuscript completeness was scored using 12 questions focused on 3 accelerometer reporting areas: accelerometer information, data processing and interpretation and protocol non-compliance. Variables, including publication year, journal focus and impact factor, and population studied were evaluated to assess trends in reporting completeness. Results The number of manuscripts using accelerometers to assess PA in interventions increased from 1 in 2002 to 29 in the first 7 months of 2014. Accelerometer reporting completeness correlated weakly with publication year (r=0.24, p<0.001). Correlations were greater when we assessed improvements over time in reporting data processing in manuscripts published in PA-focused journals (r=0.43, p=0.002) compared to manuscripts published in non-PA-focused journals (r=0.19, p=0.021). Only 7 of 195 (4%) manuscripts reported all components of accelerometer use, and only 132 (68%) reported more than half of the components. Conclusions Accelerometer reporting of PA in intervention studies has been poor and improved only minimally over time. We provide recommendations to improve accelerometer reporting and include a template to standardise reports.

Connecting Children and Family with Nature-Based Physical Activity

Abstract Background: As the obesity epidemic expands to include younger Americans, there is greater need to understand youth experiences and to identify innovative strategies to promote physical activity in children and adolescents. Connecting children and families with nature-based activities is an example of a strategy that may promote physical activity and other aspects of health and well-being in children and youth. Purpose: It is important to determine which aspects of activity in nature youth (and families) find most and least appealing, as well as characteristics of an ideal program. This study is intended to provide a needs assessment and recommended design for a community outreach program. Methods: Six focus groups were conducted with parents and youth in rural Michigan. Thirty-eight of the 42 participants were female. Results: Content analysis generated three major results: (1) Youth enjoy nature, but could be more active and engaged; (2) Adults appreciate restorative aspects of nature; youth prefer competitive and challenging experiences; and (3) Programs should promote, educate, train and create opportunities for youth to engage in healthy lifelong activities. Discussion: Participants showed interest in outdoor activity, but activities must be provided that are compelling and that address the barriers preventing populations from being more active. Translation to Health Education Practice: More effective programs must have clear objectives, build the confidence of participants, be challenging, and above all, fun. Ideal programs should offer both physical activity and ecologically meaningful nature experiences.

Energy-aware activity classification using wearable sensor networks

This paper presents implementation details, system characterization, and the performance of a wearable sensor network that was designed for human activity analysis. Specific machine learning mechanisms are implemented for recognizing a target set of activities with both out-of-body and on-body processing arrangements. Impacts of energy consumption by the on-body sensors are analyzed in terms of activity detection accuracy for out-of-body processing. Impacts of limited processing abilities for the on-body scenario are also characterized in terms of detection accuracy, by varying the background processing load in the sensor units. Impacts of varying number of sensors in terms of activity classification accuracy are also evaluated. Through a rigorous systems study, it is shown that an efficient human activity analytics system can be designed and operated even under energy and processing constraints of tiny on-body wearable sensors.

Energy Cost of Children's Structured and Unstructured Games.

BACKGROUND Limited data are available on energy cost of common childrens games using measured oxygen consumption. METHODS Children (10.6 ± 2.9 years; N = 37; 26 male, 9 female) performed a selection of structured (bowling, juggling, obstacle course, relays, active kickball) and unstructured (basketball, catch, tennis, clothespin tag, soccer) activities for 5 to 30 minutes. Resting metabolic rate (RMR) was calculated using Schofields age- and sex-specific equation. Children wore a portable metabolic unit, which measured expired gases to obtain oxygen consumption (VO2), youth METs (relative VO2/childs calculated RMR), and activity energy expenditure (kcal/kg/min). Descriptive statistics were used to summarize data. RESULTS Relative VO2 ranged from 16.8 ± 4.6 ml/kg/min (bowling) to 32.2 ± 6.8 ml/kg/min (obstacle course). Obstacle course, relays, active kickball, soccer, and clothespin tag elicited vigorous intensity (>6 METs), the remainder elicited moderate intensity (3-6 METs). CONCLUSIONS This article contributes energy expenditure data for the update and expansion of the youth compendium.

Accelerometer responsiveness to change between structured and unstructured physical activity in children and adolescents

ABSTRACT This study examined if accelerometer-based assessments of physical activity were responsive to changes in physical activity level commensurate with performing structured versus unstructured activity in youth. Youth (6–16 years; N = 206) participated in a simulated after-school program that included structured and unstructured games on four occasions over a 3-year period. Recruitment occurred in 2007/2008 and data collection ended in 2011. Participants wore an Actigraph GT1M accelerometer on the hip. The Evenson cut-points were used to determine the time spent in each physical activity intensity, and standardized response means (SRM) were calculated and converted to standard effect sizes to be interpreted according to Cohen’s guidelines. SRMs ranged from trivial (0.16) to high (2.07), with the majority (75%) being classified as moderate or high. Our findings suggest that accelerometry was sensitive to differences in physical activity associated with structured compared to unstructured play, supporting the utility of accelerometry in evaluating activity-promoting interventions.

Predictability Of Vo2max Using A Gps Watch: 2233 Board #246 June 1 2

Using accurate submaximal methodologies to estimate VO2max is a convenient alternative to maximal exercise testing. Submaximal testing is practical because it provides a cheaper, more time-efficient alternative to maximal testing and allows a wider range of individuals to be tested.PURPOSE: To exami

Age-related differences in omni-rpe scale validity in youth: A longitudinal analysis

UNLABELLED RPE scales are used in exercise science research to assess perceptions of physical effort. RPE scale validity has been evaluated by assessing correlations between RPE and physiological indicators. Cross-sectional studies indicate that RPE scale validity improves with age; however, this has not been studied longitudinally. PURPOSE This study aimed to examine age-related trends in OMNI-RPE scale validity, using a longitudinal study design, and HR and oxygen uptake (V˙O2) as criterion measures. METHODS Participants performed eleven 5-min activity trials at baseline, 12-, 24-, and 36-month follow-up (V˙O2 data: N = 160; HR data: N = 138). HR and V˙O2 between minutes 2.5 and 4.5 of each activity were recorded. At the end of each activity, participants reported RPE. Children were stratified into the following age-groups: 6-8, 9-10, 11-12, and ≥13 yr. Within-subject correlations between OMNI-RPE and HR/V˙O2 were calculated at each time point. Differences between correlations for consecutive time points were evaluated using 95% confidence intervals. RESULTS Among children age 6-8 yr at baseline, correlations progressed from 0.67 to 0.78 (V˙O2) and from 0.70 to 0.79 (HR) for 36 months. Among children age 9-10 yr at baseline, the mean within-subject correlation was 0.78 at baseline and 0.81 at 36-month follow-up. Among children age 11-12 and ≥13 yr at baseline, OMNI-RPE ratings demonstrated strong validity (r ≥ 0.82) at each time point. CONCLUSIONS For the 36-month follow-up, OMNI-RPE scale validity improved among children age 6-8 yr at baseline and remained strong among children age 9-10, 11-12, and ≥13 yr at baseline. Moderate correlations for the youngest participants suggest that caution should be used when interpreting OMNI-RPE reports from children younger than 8 yr.