Background Cardiovascular fitness has important implications for current and future health in children. Purpose In this paper, criterion-referenced standards are developed for aerobic capacity (an ...indicator of cardiovascular fitness) based on receiver operating characteristic (ROC) curves. Methods The sample was drawn from participants aged 12–18 years in the National Health and Nutrition Examination Survey (1999–2002, N=1966). Subjects completed a treadmill exercise test from which maximal oxygen uptake (VO2 max) was estimated from heart rate response. Metabolic syndrome was classified using previously published standards based on the National Cholesterol Education Program/Adult Treatment Panel III adult values at age 20 years. Using aerobic fitness z-scores as the test and metabolic syndrome as the criterion, ROC curve analysis was used to identify aerobic-capacity thresholds. Results The area under the curve (AUC) value for boys (83.1%) was high, indicating good utility for detecting risk of metabolic syndrome with aerobic fitness values. The AUC for girls (77.2%) was slightly below the recommended value of 80%. Although the ROC plots identified a defensible point for classifying levels of fitness, the approach in the present study was to establish two independent thresholds, one aimed at high specificity and one aimed at high sensitivity. The resulting z values for the low- and higher-risk threshold lines were then converted back to VO2 max estimates using published LMS (L=skewness, M=median, and S=coefficient of variation) parameters. Values at the low-risk threshold ranged from 40 to 44 mL/kg/min for boys and from 38 to 40 mL/kg/min for girls. Conclusions In summary, aerobic fitness can be used with moderate accuracy to differentiate between adolescents with and without metabolic syndrome. Age- and gender-specific aerobic-capacity thresholds for creating separate risk groups were identified using nationally representative growth percentiles.
Background To date, several studies have been published outlining reference percentiles for BMI in children and adolescents. In contrast, there are limited reference data on percent body fat (%BF) in ...U.S. youth. Purpose The purpose of this study was to derive smoothed percentile curves for %BF in a nationally representative sample of U.S. children and adolescents. Methods Percent fat was derived from the skinfold thicknesses of those aged 5–18 years from three cross-sectional waves of the National Health and Nutrition Examination Survey (NHANES) IV (1999–2000, 2001–2002, and 2003–2004; N=8269). The LMS (L=skewness, M=median, and S=coefficient of variation) regression method was used to create age- and gender-specific smoothed percentile curves of %BF. Results Growth curves are similar between boys and girls until age 9 years. However, whereas %BF peaks for boys at about age 11 years, it continues to increase for girls throughout adolescence. Median %BF at age 18 years is 17.0% and 27.8% for boys and girls, respectively. Conclusions Growth charts and LMS values based on a nationally representative sample of U.S. children and adolescents are provided so that future research can identify appropriate cut-off values based on health-related outcomes. These percentiles are based on skinfolds, which are widely available and commonly used. Using %BF instead of BMI may offer additional information in epidemiologic research, fitness assessment, and clinical settings.
Introduction This study describes the calibration and validity of the Youth Activity Profile (YAP) for use in the National Cancer Institute’s Family Life, Activity, Sun, Health, and Eating (FLASHE) ...study. The calibrated YAP was designed to estimate minutes of moderate to vigorous physical activity (MVPA) and sedentary behavior (SB). Methods The YAP was calibrated/validated in adolescents (aged 12–17 years) using cross-sectional data from the FLASHE study. Participants wore a GT3X+ ActiGraph on the dominant wrist for 7 days and then completed the YAP. Calibration was conducted for school ( n =118); out of school ( n =119); weekend ( n =61); and SB ( n =116) subsections of the YAP and by regressing percentage time in MVPA/SB (%MVPA/%SB) on each respective YAP subsection score, age, and the interaction between these two. The final algorithms were applied to independent samples ( n =39–51) to examine validity (median absolute percentage error, equivalence testing). Results The final algorithms explained 15% (school); 16% (out of school); and 12% (weekend) of the variability in GT3X+ %MVPA and 7% of the variability in GT3X+ %SB. The calibrated algorithms were applied to independent samples and predicted GT3X+ minutes of MVPA/SB, with median absolute percentage error values ranging from 12.5% (SB section) to 32.5% (weekend section). Predicted values obtained from the YAP were within 10%–20% of those produced by the GT3X+. Conclusions The YAP-predicted minutes of MVPA/SB resulted in similar group estimates obtained from an objective measure. The YAP offers good utility for large-scale research projects to characterize PA/SB levels among groups of youth.
There is a need to develop accurate devices for measuring daily energy expenditure under free-living conditions, particularly given our current obesity epidemic.
The purpose of the present study was ...to evaluate the validity of energy expenditure estimates from two portable armband devices, the SenseWear Pro3 Armband (SWA) monitor and the SenseWear Mini Armband (Mini) monitor, under free-living conditions.
Participants in the study (30 healthy adults aged 24-60 yr) wore both monitors for 14 consecutive days, including while sleeping. Criterion values for total energy expenditure (TEE) were determined using doubly labeled water (DLW), the established criterion standard method for free-living energy expenditure assessment.
The average TEE estimates were within 112 kcal·d−¹ for the SWA and within 22 kcal·d−¹ for the Mini, but the absolute error rates (computed as the average absolute value of the individual errors) were similar for the two monitors (SWA = 8.1% ± 6.8%, Mini = 8.3% ± 6.5%). Using intraclass correlation (ICC) analysis, significant agreements were found between the SWA and DLW estimates of energy expenditure (ICC = 0.80, 95% CI = 0.89-0.70) and between the Mini and DLW (ICC = 0.85, 95% CI = 0.92-0.76). Graphical plots of the DLW TEE values against the difference between DLW and monitor estimates of TEE showed that the agreement was consistent across a range of TEE values.
The SenseWear Pro3 and the SenseWear Mini armbands show promise for accurately measuring daily energy expenditure under free-living conditions. However, more work is needed to improve the ability of these monitors to accurately measure energy expenditure at higher levels of expenditure.
A wide array of accelerometer-based activity monitors has been developed to facilitate objective monitoring of physical activity behaviors, but it has proven difficult to equate outputs from ...different monitors. On the surface, commercially available monitors seem to be performing the same basic task-monitoring total body acceleration. However, differences in sensor properties and internal data processing have made it difficult to directly compare output from different monitors. In recent years, many new competing technologies have been released into the market, compounding the challenge of evaluating monitor equivalency and the relative strengths and limitations of different monitors. To advance physical activity assessment and improve our ability to compare results across studies using different monitors, it is important to conduct functional equivalency studies in a standardized and systematic way. This article summarizes issues associated with monitor equivalency and proposes methods for standardization and quality control in future research.
Abstract Objectives The purpose of this study is to provide an overview of the evidence on the calibration of ActiGraph accelerometers to quantify moderate-to-vigorous physical activity (MVPA) for ...youth through the use of cut-points and describe the independent validation studies comparing the accuracy of the developed cut-points to a criterion measure. Design A systematic review. Methods Studies were identified that: (a) developed ActiGraph accelerometer cut-points for children and youth (calibration study); or (b) performed an independent validation of already established cut-points (validation study). Both calibration studies and independent validation studies were retrieved through a systematic search of online databases. According to proposed guidelines for designing accelerometer calibration studies, each calibration study was evaluated on the following criteria: quality of a criterion measure employed; epoch length; inclusion of a variety of activities; and sample size. Results A total of 11 calibration studies were identified. Two studies met all four criteria for a calibration study. A total of 4 independent validation studies were identified. Three of them reported that no cut-points accurately classified moderate-to-vigorous physical activity (MVPA) across all ranges of physical activity intensity levels in comparison to a criterion measure. The fourth study reported two sets of cut-points that under laboratory conditions, accurately classified moderate-to-vigorous physical activity (MVPA) compared to indirect calorimetry. Conclusions Limited evidence suggests that two sets of cut-points correctly classify ActiGraph counts into moderate-to-vigorous physical activity (MVPA). However, limitations with calibration and validation studies indicate greater efforts aimed at designing high quality studies are needed to confirm these findings.
Obesity disproportionally impacts rural, lower-income children in the United States. Primary care providers are well-positioned to engage parents in early obesity prevention, yet there is a lack of ...evidence regarding the most effective care delivery models. The ENCIRCLE study, a pragmatic cluster-randomized controlled trial, will respond to this gap by testing the comparative effectiveness of standard care well-child visits (WCV) versus two enhancements: adding a patient-reported outcome (PRO) measure (PRO WCV) and PRO WCV plus Food Care (telehealth coaching and a grocery store tour).
A total of 2,025 parents and their preschool-aged children (20-60 months of age) will be recruited from 24 Geisinger primary care clinics, where providers are randomized to the standard WCV, PRO WCV, or PRO WCV plus Food Care intervention arms. The PRO WCV includes the standard WCV plus collection of the PRO-the Family Nutrition and Physical Activity (FNPA) risk assessment-from parents. Parents complete the PRO in the patient-portal or in the clinic (own device, tablet, or kiosk), receive real-time feedback, and select priority topics to discuss with the provider. These results are integrated into the child's electronic health record to inform personalized preventive counseling by providers. PRO WCV plus Food Care includes referrals to community health professionals who deliver evidence-based obesity prevention and food resource management interventions via telehealth following the WCV. The primary study outcome is change in child body mass index z-score (BMIz), based on the World Health Organization growth standards, 12 months post-baseline WCV. Additional outcomes include percent of children with overweight and obesity, raw BMI, BMI50, BMIz extended, parent involvement in counseling, health behaviors, food resource management, and implementation process measures.
Study findings will inform health care systems' choices about effective care delivery models to prevent childhood obesity among a high-risk population. Additionally, dissemination will be informed by an evaluation of mediating, moderating, and implementation factors.
ClinicalTrials.gov identifier (NCT04406441); Registered May 28, 2020.
A lack of standardization with accelerometry-based monitors has made it hard to advance applications for both research and practice. Resolving these challenges is essential for developing methods for ...consistent, agnostic reporting of physical activity outcomes from wearable monitors in clinical applications.
This article reviewed the literature on the methods used to evaluate the validity of contemporary consumer activity monitors. A rationale for focusing on energy expenditure as a key outcome measure in validation studies was provided followed by a summary of the strengths and limitations of different analytical methods. The primary review included 23 recent validation studies that collectively reported energy expenditure estimates from 58 monitors relative to values from appropriate criterion measures.
The majority of studies reported weak indicators such as correlation coefficients (87%), but only half (52%) reported the recommended summary statistic of mean absolute percent error needed to evaluate actual individual error. Fewer used appropriate tests of agreement such as equivalence testing (22%).
The use of inappropriate analytic methods and incomplete reporting of outcomes is a major limitation for systematically advancing research with both research grade and consumer-grade activity monitors. Guidelines are provided to standardize analytic methods and reporting in these types of studies to enhance the utility of the devices for clinical mHealth applications.
This study evaluates whether a health club membership is associated with meeting the US physical activity (PA) guidelines and/or favorable cardiovascular health.
Using cross-sectional data of health ...club members (n = 204) and non-members (n = 201) from April to August 2013, this is the first study to our knowledge to examine a health club membership in relation to objectively measured cardiovascular health indicators including resting blood pressure, resting heart rate, body mass index, waist circumference, and cardiorespiratory fitness based on a non-exercise test algorithm. To determine the total PA and sedentary time, this study used a comprehensive PA questionnaire about both aerobic and resistance activities at the health club, as well as lifestyle activities in other settings, which was developed based on the International Physical Activity Questionnaire (IPAQ).
The odds ratios (95% confidence interval) of meeting either the aerobic, resistance, or both aerobic and resistance PA guidelines for members compared to non-members were 16.5 (9.8-27.6), 10.1 (6.2-16.3), and 13.8 (8.5-22.4), respectively. Significant associations of health club membership with more favorable cardiovascular health outcomes and sedentary behavior were observed for resting heart rate (B: -4.8 b/min, p<0.001), cardiorespiratory fitness (B: 2.1 ml/kg/min, p<0.001), and sedentary time (B: -1.4 hours, p<0.001). Participants with a health club membership of >1 year had more favorable health outcomes, with a smaller waist circumference (men, B: -4.0 cm, p = 0.04; women, B: -3.4 cm, p = 0.06), compared to non-members.
Health club membership is associated with significantly increased aerobic and resistance physical activity levels and more favorable cardiovascular health outcomes compared to non-members. However, longitudinal, randomized controlled trials would be clearly warranted as cross-sectional data prohibits causal inferences.
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