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Early observations that only a small proportion of U.S. adults were engaging in enough aerobic physical activity to provide substantial health benefit helped shape our public health messaging for physical activity. This messaging has consistently indicated that most adults should increase their activity levels. However, it has been difficult to accurately estimate the proportion of adults who engage in sufficient levels of aerobic activity in the population, with survey-based estimates ranging from 22% in 1994 to 54% in 2018 and widely differing estimates from device-based measures. Recent accelerometer-based studies of physical activity and mortality risk provide new evidence that at least 50% of U.S. adults engage in enough aerobic physical activity to be at low risk for premature mortality. We argue that this observation should lend greater confidence to our current survey-based surveillance estimates, which indicate that a large proportion of adults is physically active. This new insight may also provide clues that could further strengthen our public health messaging for physical activity by placing more emphasis on the maintenance of healthy activity levels throughout life and possibly by using descriptive social norms as an additional intervention element--while continuing current efforts to encourage the adoption of healthy activity levels for less active adults in the population. [ABSTRACT FROM AUTHOR]

Background Studies of sleep and prostate cancer are almost entirely based on self-report, with limited research using actigraphy. Our goal was to evaluate actigraphy-measured sleep and prostate cancer and to expand on findings from prior studies of self-reported sleep. Methods We prospectively examined 34 260 men without a history of prostate cancer in the UK Biobank. Sleep characteristics were measured over 7 days using actigraphy. We calculated sleep duration, onset, midpoint, wake-up time, social jetlag (difference in weekend-weekday sleep midpoints), sleep efficiency (percentage of time spent asleep between onset and wake-up time), and wakefulness after sleep onset. Cox proportional hazards models were used to estimate covariate-adjusted hazards ratios (HRs) and 95% confidence intervals (CIs). Results Over 7.6 years, 1152 men were diagnosed with prostate cancer. Sleep duration was not associated with prostate cancer risk. Sleep midpoint earlier than 4:00 am was not associated with prostate cancer risk, though sleep midpoint of 5:00 am or later was suggestively associated with lower prostate cancer risk but had limited precision (earlier than 4:00 am vs 4:00-4:59 am HR = 1.00, 95% CI = 0.87 to 1.16; 5:00 am or later vs 4:00-4:59 am HR = 0.79, 95% CI = 0.57 to 1.10). Social jetlag was not associated with greater prostate cancer risk (1 to <2 hours vs <1 hour HR = 1.06, 95% CI = 0.89 to 1.25; ≥2 hours vs <1 hour HR = 0.90, 95% CI = 0.65 to 1.26). Compared with men who averaged less than 30 minutes of wakefulness after sleep onset per day, men with 60 minutes or more had a higher risk of prostate cancer (HR = 1.20, 95% CI = 1.00 to 1.43). Conclusions Of the sleep characteristics studied, higher wakefulness after sleep onset—a measure of poor sleep quality—was associated with greater prostate cancer risk. Replication of our findings between wakefulness after sleep onset and prostate cancer are warranted. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Purpose: The present study estimated the long-term reproducibility of accelerometer-based measures over 6 months in adults and the implications for statistical power, and attenuation in regression coefficients for future activity–disease studies. Methods: We used data from 914 adults in the Interactive Diet and Activity Tracking in AARP study. Participants wore an activPAL 3 (AP) and an ActiGraph GT3X (AG) twice, 6 months apart. AP measures included time spent sitting or lying, standing, and stepping, whereas AG measures included time spent in sedentary, light, and moderate-to-vigorous physical activity (PA). Reproducibility of each metric and implications for epidemiological studies were determined based on intraclass correlation coefficients (ICC; 95% confidence interval). Results: The ICC values for AP estimates were 0.58 (95% confidence interval, 0.53–0.63) for sitting, 0.62 (0.57–0.67) for standing, and 0.57 (0.51–0.62) for stepping. The ICC values for AG were 0.56 (0.50–0.61) for sedentary, 0.54 (0.49–0.60) for light PA, and 0.58 (0.52–0.63) for moderate-to-vigorous PA. Modeling showed that increasing the number of replicate administrations to two or three resulted in the most noticeable increases in ICC values, statistical power, and reductions in attenuation coefficients. For example, administering the AP twice reduced within-subject variability by half and resulted in an increase in the ICC associated with sitting time from 0.58 to 0.74. Similar comparisons for AG and measure of sedentary time resulted in an increase in ICC values from 0.56 to 0.72. Increasing the number of replicate administrations from one to two reduced the attenuation in activity–outcome associations from 40% to 25%. Conclusion: Accelerometer-based classifications of activity are moderately stable over time, but there is considerable within-subject variability that needs to be considered when estimating usual activity in future studies. [ABSTRACT FROM AUTHOR]

Importance: It is unclear whether the number of steps per day and the intensity of stepping are associated with lower mortality.Objective: Describe the dose-response relationship between step count and intensity and mortality.Design, Setting, and Participants: Representative sample of US adults aged at least 40 years in the National Health and Nutrition Examination Survey who wore an accelerometer for up to 7 days ( from 2003-2006). Mortality was ascertained through December 2015.Exposures: Accelerometer-measured number of steps per day and 3 step intensity measures (extended bout cadence, peak 30-minute cadence, and peak 1-minute cadence [steps/min]). Accelerometer data were based on measurements obtained during a 7-day period at baseline.Main Outcomes and Measures: The primary outcome was all-cause mortality. Secondary outcomes were cardiovascular disease (CVD) and cancer mortality. Hazard ratios (HRs), mortality rates, and 95% CIs were estimated using cubic splines and quartile classifications adjusting for age; sex; race/ethnicity; education; diet; smoking status; body mass index; self-reported health; mobility limitations; and diagnoses of diabetes, stroke, heart disease, heart failure, cancer, chronic bronchitis, and emphysema.Results: A total of 4840 participants (mean age, 56.8 years; 2435 [54%] women; 1732 [36%] individuals with obesity) wore accelerometers for a mean of 5.7 days for a mean of 14.4 hours per day. The mean number of steps per day was 9124. There were 1165 deaths over a mean 10.1 years of follow-up, including 406 CVD and 283 cancer deaths. The unadjusted incidence density for all-cause mortality was 76.7 per 1000 person-years (419 deaths) for the 655 individuals who took less than 4000 steps per day; 21.4 per 1000 person-years (488 deaths) for the 1727 individuals who took 4000 to 7999 steps per day; 6.9 per 1000 person-years (176 deaths) for the 1539 individuals who took 8000 to 11 999 steps per day; and 4.8 per 1000 person-years (82 deaths) for the 919 individuals who took at least 12 000 steps per day. Compared with taking 4000 steps per day, taking 8000 steps per day was associated with significantly lower all-cause mortality (HR, 0.49 [95% CI, 0.44-0.55]), as was taking 12 000 steps per day (HR, 0.35 [95% CI, 0.28-0.45]). Unadjusted incidence density for all-cause mortality by peak 30 cadence was 32.9 per 1000 person-years (406 deaths) for the 1080 individuals who took 18.5 to 56.0 steps per minute; 12.6 per 1000 person-years (207 deaths) for the 1153 individuals who took 56.1 to 69.2 steps per minute; 6.8 per 1000 person-years (124 deaths) for the 1074 individuals who took 69.3 to 82.8 steps per minute; and 5.3 per 1000 person-years (108 deaths) for the 1037 individuals who took 82.9 to 149.5 steps per minute. Greater step intensity was not significantly associated with lower mortality after adjustment for total steps per day (eg, highest vs lowest quartile of peak 30 cadence: HR, 0.90 [95% CI, 0.65-1.27]; P value for trend = .34).Conclusions and Relevance: Based on a representative sample of US adults, a greater number of daily steps was significantly associated with lower all-cause mortality. There was no significant association between step intensity and mortality after adjusting for total steps per day. [ABSTRACT FROM AUTHOR]

Purpose: Accelerometers are used to objectively measure physical behaviors in free-living environments, typically for seven consecutive days or more. We examined whether participants experience "wear fatigue," a decline in wear time day over day, during typical assessment period acquired in a nationally representative sample of 6- to 80-yr-olds in the United States. Methods: Participants were instructed to wear an ActiGraph GT3X+ on their nondominant wrist continuously for seven consecutive days. Participants with seven complete days of recorded data, regardless of wear status, were included in the analyses (N = 13,649). Wear was scored with the sleep, wake, and nonwear algorithm. Results: Participants averaged 1248 ± 3.6 min·d−1 (mean ± SE) of wear over the assessment, but wear time linearly decreased from day 1 (1295 ± 3.2 min) to day 7 (1170 ± 5.3 min), resulting in a wear fatigue of −18.1 ± 0.7 min·d−1 (β ± SE). Wear fatigue did not differ by sex but varied by age-group—highest in adolescents (−26.8 ± 2.4 min·d−1) and lowest in older adults (−9.3 ± 0.9 min·d−1). Wear was lower in evening (1800–2359 h) and early morning (0000–0559 h) compared with the middle of the day and on weekend days compared with weekdays. We verified similar wear fatigue (−23.5 ± 0.7 min·d−1) in a separate sample (N = 14,631) with hip-worn devices and different wear scoring. Applying minimum wear criteria of ≥10 h·d−1 for ≥4 d reduced wear fatigue to −5.3 and −18.7 min·d−1 for the wrist and hip, respectively. Conclusions: Patterns of wear suggest noncompliance may disproportionately affect estimates of sleep and sedentary behavior, particularly for adolescents. Further study is needed to determine the effect of wear fatigue on longer assessments. [ABSTRACT FROM AUTHOR]

ABSTRACT BACKGROUND We examined the impact of the Fuel Up to Play 60 ( FUTP60) program on children's body mass index ( BMI) and aerobic capacity ( AC). METHODS Participation in the FUTP60 and both BMI and AC profiles were collected through the NFL PLAY 60 FitnessGram Partnership Project involving over 100 schools from 22 US states. We specifically examined the distributions of BMI and AC among participating versus nonparticipating schools in the 2012-2013 school year. Hierarchical linear models tested the impact of participation and availability of additional funding for program implementation on the proportions of youth meeting FitnessGram health-related fitness standards (ie, Needs Improvement-Health Risk [ NIHR] and Healthy Fitness Zone [ HFZ] categories). RESULTS After 1 year implementing the program, participating schools had lower proportions of boys (−4.1 ± 2.0%, p = .04) and girls (−4.5 ± 2.0%, p = .03) in the NIHR for BMI, and lower proportion of girls (−9.7 ± 4.0%, p = .02) in the NIHR for AC. There were no differences in the distributions for the HFZ and the availability of additional funding did not alter the relationships (p > .05). CONCLUSIONS This study provides preliminary evidence that participation in the FUTP60 is associated with improved profiles of health-related fitness. [ABSTRACT FROM AUTHOR]

Objectives: Although FitnessGram fitness data on aerobic capacity and body mass index (BMI) have been collected in public schools in Georgia since the 2011-2012 school year, the data have not been analyzed. The primary objective of our study was to use these data to assess changes in fitness among school-aged children in Georgia between 2011 and 2014. A secondary objective was to determine if student fitness differed by school size and socioeconomic characteristics. Methods: FitnessGram classifies fitness into the Healthy Fitness Zone (HFZ) or not within the HFZ for aerobic capacity and BMI. We used data for 3 successive school years (ie, 2011-2012 to 2013-2014) obtained from FitnessGram testing of students in >1600 schools. We calculated the percentage of students who achieved the HFZ for aerobic capacity and BMI. We used growth curve models to estimate the annual changes in these proportions, and we determined the effect of school size and socioeconomic status on these changes. Results: Both elementary school boys (β = 1.31%, standard error [SE] = 0.23%, P < .001) and girls (β = 1.53%, SE = 0.26%, P < .001) had significant annual increases in achievement of HFZ for aerobic capacity. Elementary school boys (β = 3.11%, SE = 0.32%, P < .001) and girls (β = 3.09%, SE = 0.32%, P < .001) also had significant increases in their BMI HFZ achievement proportions, although these increases occurred primarily between 2011-2012 and 2012-2013. Body mass index HFZ achievement proportions were mixed for middle school students, and we did not observe increases for high school students. Larger school size and higher school socioeconomic status were associated with better aerobic capacity and BMI fitness profiles. Conclusions: Surveillance results such as these may help inform the process of designing state and local school-based fitness promotion and public health programs and tracking the results of those programs. [ABSTRACT FROM AUTHOR]

Objectives: The FitnessGram Healthy Fitness Zone continuum (HFZc) score reflects the relative difference of a person's body mass index (BMI) from the established FitnessGram standard. As such, it may provide added utility for public health programming and research on obesity among school-aged children and adolescents. We used the standard BMI Z (BMIz) score and the alternative HFZc score to describe changes in BMI of school-aged children and adolescents in Georgia over time. Methods: We compiled 2012-2014 BMI data from the Georgia FitnessGram database. The sample included 162 992 boys and 141 711 girls enrolled in 239 schools from a large urban district in Georgia. We analyzed trends in BMIz and HFZc scores separately for normal-weight, overweight, and obese categories for school-aged children and adolescents using hierarchical linear models. Results: From 2012 to 2014, the BMIz score shifted favorably in up to 40.7% (2052/5047) of normal-weight, 51.0% (758/1485) of overweight, and 52.8% (5430/10 279) of obese students. We also found favorable shifts in HFZc score in up to 69.8% (105 831/151 739) of normal-weight, 78.3% (3605/4603) of overweight, and 80.8% (8305/10 279) of obese students. Conclusions: Compared with the BMIz score, the HFZc score may be a better indicator of favorable changes in BMI over time among school-aged children and adolescents with different baseline BMI levels, making it potentially valuable for use in individualized assessments, school programs, obesity research, and public health curriculum and policy development. [ABSTRACT FROM AUTHOR]

The purpose of the study was to describe current levels of musculoskeletal fitness (MSF) in U.S. youth by creating nationally representative age-specific and sex-specific growth curves for handgrip strength (including relative and allometrically scaled handgrip), modified pull-ups, and the plank test. Participants in the National Youth Fitness Survey (n = 1,453) were tested on MSF, aerobic capacity (via submaximal treadmill test), and body composition (body mass index [BMI], waist circumference, and skinfolds). Using LMS regression, age-specific and sex-specific smoothed percentile curves of MSF were created and existing percentiles were used to assign age-specific and sex-specific z-scores for aerobic capacity and body composition. Correlation matrices were created to assess the relationships between z-scores on MSF, aerobic capacity, and body composition. At younger ages (3-10 years), boys scored higher than girls for handgrip strength and modified pull-ups, but not for the plank. By ages 13-15, differences between the boys and girls curves were more pronounced, with boys scoring higher on all tests. Correlations between tests of MSF and aerobic capacity were positive and low-to-moderate in strength. Correlations between tests of MSF and body composition were negative, excluding absolute handgrip strength, which was inversely related to other MSF tests and aerobic capacity but positively associated with body composition. The growth curves herein can be used as normative reference values or a starting point for creating health-related criterion reference standards for these tests. Comparisons with prior national surveys of physical fitness indicate that some components of MSF have likely decreased in the United States over time. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study tests calibration models to re-scale context-specific physical activity (PA) items to accelerometer-derived PA. A total of 195 4th–12th grades children wore an Actigraph monitor and completed the Physical Activity Questionnaire (PAQ) one week later. The relative time spent in moderate-to-vigorous PA (MVPA%) obtained from the Actigraph at recess, PE, lunch, after-school, evening and weekend was matched with a respective item score obtained from the PAQ’s. Item scores from 145 participants were calibrated against objective MVPA%using multiple linear regression with age, and sex as additional predictors. Predicted minutes of MVPA for school, out-of-school and total week were tested in the remaining sample (n = 50) using equivalence testing. The results showed that PAQ β-weights ranged from 0.06 (lunch) to 4.94 (PE) MVPA%(P < 0.05) and models root mean square error ranged from 4.2% (evening) to 20.2% (recess). When applied to an independent sample, differences between PAQ and accelerometer MVPA at school and out-of-school ranged from −15.6 to +3.8 min and the PAQ was within 10–15% of accelerometer measured activity. This study demonstrated that context-specific items can be calibrated to predict minutes of MVPA in groups of youth during in- and out-of-school periods. [ABSTRACT FROM PUBLISHER]

Introduction: The NFL PLAY 60 campaign has actively promoted physical activity and healthy eating in youth through programs such as the PLAY 60 Challenge and Fuel Up to PLAY 60. The purpose of the study was to evaluate the impact of NFL PLAY 60 programming on longitudinal trajectories of youth aerobic capacity and BMI.Study Design: Data were from the NFL PLAY 60 FitnessGram Partnership Project, a large participatory research project designed to promote physical activity and healthy eating among Kindergarten through 12th grade children and adolescents.Setting/participants: The programming was led by teachers in school settings across 32 NFL franchise markets. A range of 50,000-100,000 students from 497 schools completed FitnessGram assessments annually starting in 2011 and continuing through 2015. The analysis was conducted in 2015.Intervention: Adoption of NFL PLAY 60 programming was encouraged but not required and the program implementation was evaluated each year. The adoption was evaluated through self-reported annual survey.Main Outcome Measures: School assessments of aerobic capacity and BMI were evaluated using FitnessGram standards to calculate the percentage of students meeting the Healthy Fitness Zone for each test. Growth curve modeling was used to estimate the longitudinal trajectories.Results: About 19% of schools were classified as programming schools. Annual improvements in aerobic capacity were significantly greater in schools that participated in the programs for both girls (3.0%, p<0.01) and boys (2.9%, p<0.01) compared with non-programming schools. The annual improvements in BMI Healthy Fitness Zone achievement were also higher in girls (1.3%, p<0.05) and in boys (1.2%, p<0.05) from schools that participated in the programs versus non-participating schools. Schools that implemented the programs for the entire 4-year period tended to have better improvements in aerobic capacity than schools enrolled for only 2 or 3 years (p<0.05).Conclusions: The results of these longitudinal analyses support the utility of the NFL PLAY 60 physical activity promotion programs for improving youth aerobic capacity and potentially helping to reverse the prevalence of overweight/obesity. However, the overall program adoption rate is low. [ABSTRACT FROM AUTHOR]

ABSTRACT BACKGROUND To advance research on youth fitness promotion it is important to understand factors that may explain the disparities in fitness. METHODS We evaluated data from the FitnessGram NFL PLAY60 Partnership Project to examine school factors influencing aerobic capacity ( AC) and body mass index ( BMI) in schoolchildren. Individual observations for AC (157,971 students from 675 schools) and BMI (178,274 students from 630 schools) were aggregated to compute the percentage of students achieving the Healthy Fitness Zone ( HFZ). We examined achievements using adjusted linear regression models with socioeconomic status ( SES), minority status, region, enrollment, and grade as factors. RESULTS The mean HFZ for AC and BMI were 51.6% and 56.9%, respectively. SES, minority status, and enrollment were all significantly associated with AC HFZ among boys, and SES and enrollment were significant predictors of AC HFZ in girls. SES and location were significantly related to BMI HFZ among boys but only SES significantly predicted BMI HFZ in girls. Schools with higher SES had higher AC and BMI HFZ achievements. CONCLUSIONS SES was consistently associated with health-related fitness, independent of sex, but not minority status. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the agreement between estimated peak oxygen consumption (VO2peak) obtained from the Progressive Aerobic Cardiovascular Endurance Run (PACER) fitness test and equated PACER laps derived from One-Mile Run time (MR). Methods: A sample of 680 participants (324 boys and 356 girls) in Grades 7 through 12 completed both the PACER and the MR assessments. MR time was converted to PACER laps (PACER-MEQ) using previously developed conversion algorithms. Agreement between PACER and PACER-MEQ VO2peak was examined using Pearson correlations, mean absolute percent error (MAPE), and equivalence testing procedures. Classification agreement based on health-related standards was examined using sensitivity, specificity, and Kappa statistics. Results: Overall agreement between estimated VO2peak obtained from the PACER and PACER-MEQ was high in boys, r(324) = .79, R2 = .63, and moderate in girls, r(356) = .57, R2 = .33. The MAPE for estimates obtained from PACER-MEQ was 10.3% and estimates were deemed equivalent to the PACER (43.1 ± 6.9 mL/kg/min vs. 44.6 ± 0.3 mL/kg/min). Classification agreement as illustrated by sensitivity and specificity ranged from 20.4% to 90.2% and was higher for classifications in the Healthy Fitness Zone (HFZ). Kappa statistics ranged from .14 to .51 and were also higher for the HFZ. Conclusions: Equated PACER laps can be used to obtain equivalent estimates of PACER VO2peak in groups of adolescents, but some disparities can be found when students' scores are classified into the Needs Improvement Zone. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to calibrate and cross-validate the Youth Activity Profile (YAP), a self-report tool designed to capture physical activity (PA) and sedentary behaviors (SB) in youth. Methods: Eight schools in the Midwest part of the U.S. were involved and a total of 291 participants from grades 4–12 agreed to wear an accelerometer (SWA Armband) and complete the YAP in two separate weeks (5–7 days apart). Individual YAP items capture PA behavior during specific segments of the week and these items were combined with temporally matched estimates of moderate-to-vigorous PA (MVPA) and sedentary time from the SWA to enable calibration. Quantile regression procedures yielded YAP prediction algorithms that estimated MVPA at School, MVPA at Out-of-School, MVPA on Weekend, as well as time spent in SB. The YAP estimates of time spent in MVPA and SB were cross-validated using Pearson product correlations and limits of agreement, as indicative of individual error and, equivalence testing techniques as indicative of group-level error. Result: Following calibration, the correlations between YAP and SWA estimates of MVPA were low to moderate (rrange = .19 to .58) and individual-level YAP estimates of MVPA ranged from -134.9% to +110.0% of SWA MVPA values. Differences between aggregated YAP and SWA MVPA ranged from -3.4 to 21.7 minutes of MVPA at the group-level and predicted YAP MVPA estimates were within 15%, 20%, and 30%, of values from the SWA for the School, Out-of-School, and Weekend time periods, respectively. Estimates of time spent in SB were highly correlated with each other (r = .75). The individual estimates of SB ranged from -54.0% to +44.0% of SWA sedentary time, and the aggregated group-level estimates differed by 49.7 minutes (within 10% of the SWA aggregated estimates). Conclusions: This study provides preliminary evidence that the calibration procedures enabled the YAP to provide estimates of MVPA and SB that approximated values from an objective monitor. The YAP provides a simple, low-cost and educationally sound method to accurately estimate children’s MVPA and SB at the group level. [ABSTRACT FROM AUTHOR]

Purpose: Physical activity levels (PAL) are associated with mortality risk and were instrumental in estimating national energy requirements, but we are unaware of population-based estimates of PAL in US adults. Thus, we conducted a nationwide survey using a validated previous-day recall method to estimate PAL and the behavioral determinants of low and higher PAL. Methods: Participants from the AmeriSpeak panel 20–75 yr of age (N = 2640) completed Activities Completed over Time in 24-hours previous-day recalls. PAL values were estimated as the average metabolic equivalent value over 24 h. Recalls were conducted on randomly selected days in October and November 2019. Survey sample design weights were applied to reflect the US population. Results: Mean age was 45.3 yr, 51% were female, 67% were non-Hispanic White, and 37% had a body mass index of ≥30 kg·m−2. US adults reported a mean PAL of 1.63 (95% confidence interval, 1.60–1.65), and 39% (37%–42%) of adults reported PAL ≥1.6 on a given day. Men reported higher PAL than women (1.67 vs 1.59), and older adults reported lower PAL. Adults with PAL <1.4 spent 81% (12.1 h·d−1) of their waking day sedentary and 19% (2.7 h·d−1) in total physical activity. Adults with PAL considered to be "active"(1.6–1.89) spent only 49% (8.0 h·d−1) of their waking day sedentary, and 51% (8.3 h·d−1) physically active. Conclusions: Our study provides novel estimates of PAL in a nationwide sample of US adults and a description of the type and intensity of sedentary and physically active behaviors contributing to low and higher PAL. These findings may inform public health messages aimed at increasing physical activity in adults and potentially contribute to obesity prevention efforts. [ABSTRACT FROM AUTHOR]

Background The utility of self-report measures of physical activity (PA) in youth can be greatly enhanced by calibrating self-report output against objectively measured PA data. This study demonstrates the potential of calibrating self-report output against objectively measured physical activity (PA) in youth by using a commonly used self-report tool called the Physical Activity Questionnaire (PAQ). Methods A total of 148 participants (grades 4 through 12) from 9 schools (during the 2009-2010 school year) wore an Actigraph accelerometer for 7 days and then completed the PAQ. Multiple linear regression modeling was used on 70% of the available sample to develop a calibration equation and this was cross validated on an independent sample of participants (30% of sample). Results A calibration model with age, gender, and PAQ scores explained 40% of the variance in values for the percentage of time in moderate-to-vigorous PA (%MVPA) measured from the accelerometers (%MVPA = 14.56 - (sex*0.98) - (0.84*age) + (1.01*PAQ)). When tested on an independent, hold-out sample, the model estimated %MVPA values that were highly correlated with the recorded accelerometer values (r = .63) and there was no significant difference between the estimated and recorded activity values (mean diff. = 25.3 ± 18.1 min; p = .17). Conclusions These results suggest that the calibrated PAQ may be a valid alternative tool to activity monitoring instruments for estimating %MVPA in groups of youth. [ABSTRACT FROM AUTHOR]

Background A limitation of traditional outcome studies from behavioral interventions is the lack of attention given to evaluating the influence of moderating variables. This study examined possible moderation effect of baseline activity levels on physical activity change as a result of the Ready for Recess intervention. Methods Ready for Recess (August 2009-September 2010) was a controlled trial with twelve schools randomly assigned to one of four conditions: control group, staff supervision, equipment availability, and the combination of staff supervision and equipment availability. A total of 393 children (181 boys and 212 girls) from grades 3 through 6 (8-11 years old) were asked to wear an Actigraph monitor during school time on 4-5 days of the week. Assessments were conducted at baseline (before intervention) and post intervention (after intervention). Results Initial MVPA moderated the effect of Staff supervision (β = -0.47 %; p < .05), but not Equipment alone and Staff + Equipment (p > .05). Participants in the Staff condition that were 1 standard deviation (SD) below the mean for baseline MVPA (classified as "low active") had lower MVPA levels at post-intervention when compared with their low active peers in the control condition (Mean diff = -10.8 ± 2.9 %; p = .005). High active individuals (+1SD above the mean) in the Equipment treatment also had lower MVPA values at postintervention when compared with their highly active peers in the control group (Mean diff = -9.5 ± 2.9 %; p = .009). Conclusions These results indicate that changes in MVPA levels at post-intervention were reduced in highly active participants when recess staff supervision was provided. In this study, initial MVPA moderated the effect of Staff supervision on children's MVPA after 6 months of intervention. Staff training should include how to work with inactive youth but also how to assure that active children remain active. [ABSTRACT FROM AUTHOR]

Objective: The Intuitive Eating Scale-2 (IES-2) has been shown to be a valid tool to assess the capability of eating in reaction to natural hunger/satiety cues. However, its factor structure seems to differ in function of cultural/socioeconomic backgrounds, and its psychometric properties among the adolescents with overweight/obesity (BMI-for-age percentile >85th) have not been examined yet. Thus, this study aims to 1) investigating the factorial structure/psychometric properties of IES-2 in adolescents with overweight/obesity; and 2) exploring the associations between impulsivity, quality of life disordered and intuitive eating.Methods: A total of 202 Portuguese adolescents (124 girls; 78 boys; 12-19 years) under weight-loss treatment with a mean BMI z-score of 2.41 (SD = 0.75) participated in this study. The IES-2 factor structure was explored by confirmatory factor analysis and bifactor models. Test-retest reliability analyses were performed over 6 months (n = 41) and associations between the variables under study were explored.Results: Confirmatory factor analyses with posthoc modifications resulted in a bifactor model with acceptable fit supporting one general factor (intuitive eating) and three specific factors (IES-2 subscales). The "Unconditional Permission to Eat" subscale could not be replicated in this sample. Test-retest reliability analyses suggested good temporal stability. Intuitive eating scores were negatively associated with grazing eating behavior and impulsivity (negative urgency) and positively linked to quality of life.Conclusions: An adjusted version of IES-2 can be an appropriate measure for assessing intuitive eating levels in adolescents with overweight/obesity. Research on intuitive eating has the potential to enhance pediatric weight-loss interventions. [ABSTRACT FROM AUTHOR]

BACKGROUND: School recess provides a daily opportunity for physical activity engagement. The purpose of this study was to examine physical activity levels during recess by gender, ethnicity, and grade, and establish the contribution of recess to daily school physical activity levels. METHODS: Two hundred and ten children (45% boys) from grades 3 to 6 in 4 elementary schools had their physical activity during school quantified using uni-axial accelerometry every 5 seconds for 5 consecutive school days. Data were collected in fall 2009. The proportion of time spent engaged in physical activity during daily school recess was determined using existing age-appropriate cutpoints. The relative contribution of recess to school day physical activity was also determined. RESULTS: Boys were more active than girls during recess. Girls engaged in more sedentary activity than boys. No main effects for ethnicity were observed. Children in grades 3 and 5 were more active than children in grades 4 and 6. Recess contributed 17.9% and 15.5% toward boys' and girls' school day moderate-to-vigorous physical activity, respectively. CONCLUSION: Children engaged in physical activity during recess, though interventions may be needed to increase the intensity of activity in this context. [ABSTRACT FROM AUTHOR]

We designed grip strength standards for youth by back-extrapolating cutpoints based on weakness at age 65. Existing standards, based on insufficient bone mineral content (BMC), were also compared in a nationally representative sample. Altogether, 6837 participants (n = 2199 ≤ 18.9 years of age) from the National Health and Nutrition Examination Survey had dominant hand, grip strength assessed. Lambda Mu Sigma regression was used to create percentiles of strength and identify thresholds linked with clinically relevant weakness (CRW) in older adults. Approximately 93% and 75% of young people met standards based on CRW and BMC, respectively. Non-Hispanic white and black youth were more likely to meet grip strength cutpoints. Underweight children were less likely (odds ratios = 0.20 to 0.26), while overweight/obese youth were more likely (1.38 to 2.71), to meet strength standards compared to normal weight. The standards can be used with, or in place of, normative standards when evaluating grip strength. [ABSTRACT FROM AUTHOR]

Background: The association of fitness with cancer risk is not clear. Methods: We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of lung, colorectal, endometrial, breast, and prostate cancer in a subset of UK Biobank participants who completed a submaximal fitness test in 2009-12 (N = 72,572). We also investigated relationships using two-sample Mendelian randomisation (MR), odds ratios (ORs) were estimated using the inverse-variance weighted method. Results: After a median of 11 years of follow-up, 4290 cancers of interest were diagnosed. A 3.5 ml O2⋅min−1⋅kg−1 total-body mass increase in fitness (equivalent to 1 metabolic equivalent of task (MET), approximately 0.5 standard deviation (SD)) was associated with lower risks of endometrial (HR = 0.81, 95% CI: 0.73–0.89), colorectal (0.94, 0.90–0.99), and breast cancer (0.96, 0.92–0.99). In MR analyses, a 0.5 SD increase in genetically predicted O2⋅min−1⋅kg−1 fat-free mass was associated with a lower risk of breast cancer (OR = 0.92, 95% CI: 0.86–0.98). After adjusting for adiposity, both the observational and genetic associations were attenuated. Discussion: Higher fitness levels may reduce risks of endometrial, colorectal, and breast cancer, though relationships with adiposity are complex and may mediate these relationships. Increasing fitness, including via changes in body composition, may be an effective strategy for cancer prevention. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine the criterion validity of Activities Completed over Time (ACT24), an automated previous-day recall tool designed for mobile devices for 1) estimating sedentary versus active time compared with an activPAL, and 2) estimating time spent in activity domains (e.g., work, household, leisure) compared with direct observation (DO). Methods: Over a 7-d study period, 53 participants were sent invitations to complete three automated ACT24 recalls and to wear an activPAL device. A subset (N = 24) consented to two, 3-h video-recorded DO sessions. activPAL and ACT24 data were matched by date, and agreement for sedentary versus active time was compared between methods using paired t -tests for mean differences and spearman correlations. We compared DO and ACT24 results by domain for overall time use and separately for sedentary and active time using κ statistics and tested mean differences with linear mixed models. Results: Compared with the activPAL, the mean difference in ACT24 sedentary time was 1.9% (mean (95% confidence interval), −0.17 (−0.75 to 0.40) h·d−1), and the mean difference for ACT24 active time was 2.2% (0.14 (−0.32 to 0.60) h·d−1). Correlations were R = 0.61 (95% confidence interval, 0.39 to 0.76) and R = 0.65 (0.44 to0.78) for sedentary and active time, respectively. Domain-specific agreement was substantial for leisure-time, work, and shopping/errands (κ range, 0.63–0.79), moderate for transportation (κ = 0.49), and fair for personal care and household activities (κ = 0.24 and 0.33). ACT24 estimates of average time within each domain were not significantly different from DO. Conclusions: The present study confirms that ACT24 is accurate for group-level estimation of active and sedentary time. Domain-specific agreement tended to be higher for more commonly reported activities and those that were of longer duration. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to test the convergent validity of Omron 306 using Biospace InBody 720.Method: A total of 267 participants (145 boys; aged 10.4-17.9 years) completed testing during a single session. Each measure provided percent body fat (%BF), while the InBody 720 included fat-free mass (FFM). The validity was examined using the Pearson correlation. Limits of agreement (LOA) and multiple linear regression were also used to determine the impact of both age and FFM on the associations between the 2 measures.Results: The 2 measures of %BF were correlated by .63 (p < .001) in boys and .89 (p < .001) in girls. The mean difference (i.e., InBody - Omron) for %BF in boys was - 4.7% with a lower LOA of - 20.5% and upper LOA of 11.2%. The same comparison for girls resulted in a difference of 3.0% with a lower LOA of - 10% and upper LOA of 4%. Examination of the residuals obtained from multiple linear regression indicated that FFM was the only statistically significant predictor of differences in boys (βFFM = - 0.25 ± 0.08%, p = .001). There were no significant associations for girls.Conclusions: Findings indicate that estimates of %BF obtained from Omron in boys exceed estimates from InBody 720. Disagreement was evident in younger boys with lower levels of FFM. Girls' %BF was closer between the 2 bioelectrical impedance analyzer measures (less residual) with age and FFM not explaining the disagreement. Overall, the 2 measures were not equivalent. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this article was to evaluate the validity of the Progressive Aerobic Cardiovascular and Endurance Run (PACER) test in a sample of Hungarian youth.Method: Approximately 500 participants (aged 10-18 years old) were randomly selected across Hungary to complete both laboratory (maximal treadmill protocol) and field assessments (PACER) of aerobic capacity. Agreement between lab- and PACER-derived peak oxygen consumption (VO2) was examined using linear regression and 2-sided equivalence testing techniques, respectively. The impact of agreement on the classification accuracy of peak VO2 estimates into FITNESSGRAM® fitness zones was determined with kappa statistics.Results: The final sample resulted in a total of 167 boys and 143 girls (N = 310). Analyses revealed that lab and PACER VO2 shared 13% to 18% of their variance (R(2)boys = .13, R(2)girls = .18) and that limits of agreement ranged from - 39.9 mL/kg/min to +37.6 mL/kg/min depending on the sex. The absolute error values were 14% for boys and 16% for girls; however, the average peak VO2 estimates from the PACER were within the 10% equivalence region for girls (37.2 mL/kg/min to 45.4 mL/kg/min), but not for boys (45.2 mL/kg/min to 55.2 mL/kg/min). When lab and PACER VO2 were categorized according to Fitnessgram zones, agreement was fair for both sexes (boys, Kappa = .25, and girls, Kappa = .31).Conclusions: Although the correlations between measured and predicted peak VO2 were lower than expected, the magnitude of error observed in the PACER is similar to past ranges of error observed in other studies (10%-15%), but the large individual error should be considered when interpreting individual results from this field-based measure of aerobic capacity. There was reasonable classification agreement between lab estimates and the PACER test for classification into the various fitness standards. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to cross-validate FITNESSGRAM® aerobic and body composition standards in a representative sample of Hungarian youth.Method: A nationally representative sample (N = 405) of Hungarian adolescents from the Hungarian National Youth Fitness Study (ages 12-18.9 years) participated in an aerobic capacity assessment via treadmill test to maximum to determine peak oxygen consumption (VO2peak) and a bioelectrical impedance assessment to estimate percent body fat (%BF). Additionally, metabolic syndrome status was assessed via finger-stick blood sample. Youth were categorized into Healthy Fitness Zone (HFZ) and Needs Improvement (NI) groups based on Fitnessgram standards. Prevalence of metabolic syndrome was calculated and logistic regression was used to estimate odds of metabolic syndrome.Results: Hungarian youth were generally fit with a low prevalence of metabolic syndrome. Approximately 69% to 77% of boys and 55% to 57% of girls were classified into the HFZ based on %BF and VO2peak. Youth in the NI health risk zones for VO2peak and %BF were 4 times to 5 and 2 times to 3 times more likely to have metabolic syndrome than children in the lower-risk groups, respectively.Conclusions: Fitnessgram standards for aerobic capacity and body composition were associated with metabolic syndrome status, though odds ratios were larger for VO2peak than for %BF and varied by sex. Even though these standards were developed in U.S. youth, they can be applied in Hungary and still provide a criterion-referenced indication of fitness. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this article was to evaluate the validity of the Progressive Aerobic Cardiovascular and Endurance Run (PACER) test in a sample of Hungarian youth. Method: Approximately 500 participants (aged 10–18 years old) were randomly selected across Hungary to complete both laboratory (maximal treadmill protocol) and field assessments (PACER) of aerobic capacity. Agreement between lab- and PACER-derived peak oxygen consumption (VO2) was examined using linear regression and 2-sided equivalence testing techniques, respectively. The impact of agreement on the classification accuracy of peak VO2 estimates into FITNESSGRAM® fitness zones was determined with kappa statistics. Results: The final sample resulted in a total of 167 boys and 143 girls (N = 310). Analyses revealed that lab and PACER VO2 shared 13% to 18% of their variance (R2boys =.13, R2girls =.18) and that limits of agreement ranged from − 39.9 mL/kg/min to +37.6 mL/kg/min depending on the sex. The absolute error values were 14% for boys and 16% for girls; however, the average peak VO2 estimates from the PACER were within the 10% equivalence region for girls (37.2 mL/kg/min to 45.4 mL/kg/min), but not for boys (45.2 mL/kg/min to 55.2 mL/kg/min). When lab and PACER VO2 were categorized according to Fitnessgram zones, agreement was fair for both sexes (boys, Kappa =.25, and girls, Kappa =.31). Conclusions: Although the correlations between measured and predicted peak VO2 were lower than expected, the magnitude of error observed in the PACER is similar to past ranges of error observed in other studies (10%–15%), but the large individual error should be considered when interpreting individual results from this field-based measure of aerobic capacity. There was reasonable classification agreement between lab estimates and the PACER test for classification into the various fitness standards. [ABSTRACT FROM AUTHOR]

Purpose:The purpose of this study was to test the convergent validity of Omron 306 using Biospace InBody 720.Method:A total of 267 participants (145 boys; aged 10.4–17.9 years) completed testing during a single session. Each measure provided percent body fat (%BF), while the InBody 720 included fat-free mass (FFM). The validity was examined using the Pearson correlation. Limits of agreement (LOA) and multiple linear regression were also used to determine the impact of both age and FFM on the associations between the 2 measures.Results:The 2 measures of %BF were correlated by .63 (p < .001) in boys and .89 (p < .001) in girls. The mean difference (i.e., InBody – Omron) for %BF in boys was − 4.7% with a lower LOA of − 20.5% and upper LOA of 11.2%. The same comparison for girls resulted in a difference of 3.0% with a lower LOA of − 10% and upper LOA of 4%. Examination of the residuals obtained from multiple linear regression indicated that FFM was the only statistically significant predictor of differences in boys (βFFM = − 0.25 ± 0.08%,p = .001). There were no significant associations for girls.Conclusions:Findings indicate that estimates of %BF obtained from Omron in boys exceed estimates from InBody 720. Disagreement was evident in younger boys with lower levels of FFM. Girls' %BF was closer between the 2 bioelectrical impedance analyzer measures (less residual) with age and FFM not explaining the disagreement. Overall, the 2 measures were not equivalent. [ABSTRACT FROM PUBLISHER]

Purpose:The purpose of this study was to examine region, age, and sex profiles of physical fitness in Hungarian youth.Method:A sample of 2,602 Hungarian youth aged 10 to 18 years old completed a series of physical fitness field tests: the Progressive Aerobic Cardiorespiratory Endurance Run (PACER) fitness test, body mass index (BMI), percent body fat (%BF), waist circumference (WC), curl-ups (CU), pushups (PU), trunk extension (TE), back-saver sit-and-reach (SR), handgrip (HG), and standing broad jump. Physical fitness scores were classified using FITNESSGRAM® standards, and trends for region, age, and sex were examined using logistic regression. The outcome variable represented the likelihood that a child would meet the recommended levels of fitness for health.Results:Achievement rates varied considerably by region, age, and sex. The likelihood of achieving the Healthy Fitness Zone (HFZ) varied among Hungarian regions and on all the assessments (p<  .05) with exception of the CU, PU, and HG tests (p> .05). The likelihood of achieving the HFZ was linearly related with age based on PACER, BMI, WC, %BF, CU, and SR scores (p<  .05). There were statistically significant gender differences and boys were more likely to achieve the HFZ based on PACER, WC, CU, PU, TE, and SR scores (p<  .05).Conclusions:The likelihood of achieving the recommended levels of fitness for youth varies between regions in Hungary, in most cases decreases with age, and tends to be higher in boys. This study is one of the few that provides evidence of regional, age, and sex patterns of health-related fitness using a representative sample of youth. [ABSTRACT FROM PUBLISHER]

Purpose:The purpose of this study was to create a physical education (PE) attitude scale and examine how it is associated with aerobic capacity (AC).Method:Participants (n = 961, aged 15–20 years) were randomly selected from 26 Hungarian high schools. AC was estimated from performance on the Progressive Aerobic Cardiovascular and Endurance Run test, and the attitude scale had 31 items measured on a Likert scale that ranged from 1 to 5. Principal component analysis was used to examine the structure of the questionnaire while several 2-way analyses of variance and multiple linear regression (MLR) were computed to examine trends in AC and test the association between component scores obtained from the attitude scale and AC, respectively.Results:Five components were identified: health orientation in PE (C1), avoid failure in PE (C2), success orientation in PE (C3), attitude toward physical activity (C4), and cooperation and social experience in PE (C5). There was a statistically significant main effect for sex on C3 (p < .05), C4 (p < .001), and C5 (p < .05) indicating that boys' scores were higher than girls. The Sex ×  Age interaction was also statistically significant (p < .05) and follow-up comparisons revealed sex differences in C5 for 15-year-old participants. Girls showed statistically significant higher values than boys in C5 at the age of 16 years. MLR results revealed that component scores were significantly associated with AC (p < .05). Statistically significant predictors included C1, C2, C3, and C4 for boys and C2 and C4 for girls.Conclusion:The 5-component scale seems to be suitable for measuring students' attitudes toward PE. The design of the study does not allow for direct associations between attitudes and AC but suggests that these 2 might be related. [ABSTRACT FROM PUBLISHER]

Purpose: The purpose of this study was to cross-validate FITNESSGRAM® aerobic and body composition standards in a representative sample of Hungarian youth. Method: A nationally representative sample (N = 405) of Hungarian adolescents from the Hungarian National Youth Fitness Study (ages 12–18.9 years) participated in an aerobic capacity assessment via treadmill test to maximum to determine peak oxygen consumption (VO2peak) and a bioelectrical impedance assessment to estimate percent body fat (%BF). Additionally, metabolic syndrome status was assessed via finger-stick blood sample. Youth were categorized into Healthy Fitness Zone (HFZ) and Needs Improvement (NI) groups based on Fitnessgram standards. Prevalence of metabolic syndrome was calculated and logistic regression was used to estimate odds of metabolic syndrome. Results: Hungarian youth were generally fit with a low prevalence of metabolic syndrome. Approximately 69% to 77% of boys and 55% to 57% of girls were classified into the HFZ based on %BF and VO2peak. Youth in the NI health risk zones for VO2peak and %BF were 4 times to 5 and 2 times to 3 times more likely to have metabolic syndrome than children in the lower-risk groups, respectively. Conclusions: Fitnessgram standards for aerobic capacity and body composition were associated with metabolic syndrome status, though odds ratios were larger for VO2peak than for %BF and varied by sex. Even though these standards were developed in U.S. youth, they can be applied in Hungary and still provide a criterion-referenced indication of fitness. [ABSTRACT FROM AUTHOR]

Purpose:The purpose of this study was to examine age and sex trends in anaerobic power assessed by a standing broad jump and to determine norm-referenced values for youth in Hungary.Method:A sample of 2,427 Hungarian youth (1,360 boys and 1,067 girls) completed the standing broad jump twice, and the highest distance score was recorded. Quantile regression was used to fit standing broad jump trends across linear and quadratic functions of age. Statistical significance was determined with bootstrap confidence intervals and the Wald test withp < .05. Age-by-sex specific centiles were generated and the 50th percentile was used to describe the overall patterns.Results:Standing broad jump scores increased steadily in boys from age 11 through 18 years with a discrete plateau at the end of adolescence. Girls' standing broad jump scores of those who performed above the median increased with age and plateaued later in the adolescence. Both linear and quadratic age terms were statistically significant predictors of standing broad jump trends across age (p < .05), but the relations varied depending on the percentile. The 50th percentile values resulted in 147.0 cm, 162.0 cm, 175.0 cm, 186.0 cm, 195.0 cm, 202.0 cm, 207.0 cm, and 210.0 cm for boys aged 11 to 18 years old, respectively, and 140.0 cm, 143.9 cm, 147.3 cm, 150.0 cm, 152.1 cm, 153.7 cm, 154.6 cm, and 155.0 cm for girls aged 11 to 18 years old, respectively.Conclusions:This study provides normative reference charts that take into account age and sex differences in standing broad jump performance. The proposed reference values can be used to interpret standing broad jump scores in Hungarian youth. [ABSTRACT FROM PUBLISHER]

Purpose:The purpose of this study was to examine age- and sex-related variation in handgrip strength and to determine reference values for the Hungarian population.Method:A sample of 1,086 Hungary youth (aged 11–18 years old; 654 boys and 432 girls) completed a handgrip strength assessment using a handheld dynamometer. Quantile regression was used to compute separate models for boys and girls and included a linear, cubic, and quadratic term for age to account for nonlinear patterns. These terms were tested for statistical significance using the Wald statistical test withp < .05. Age- and sex-specific centiles were generated and the 50th percentile was used to describe the overall patterns in handgrip strength.Results:The linear, cubic, and quadratic terms for age fitted the data well for boys (p < .05), while both linear and quadratic terms for age were statistically significant for girls (p < .05). The 50th percentile values resulted in 21.4 kg, 21.7 kg, 25.0 kg, 30.0 kg, 35.4 kg, 40.0 kg, 42.6 kg, and 42.0 kg for boys aged 11 to 18 years old, respectively. The same percentile resulted in 20.0 kg, 19.5 kg, 19.6 kg, 20.3 kg, 21.6 kg, 23.5 kg, 26.1 kg, and 29.2 kg for girls aged 11 to 18 years old, respectively.Conclusions:Muscle strength as determined by handgrip has distinct age-related patterns in boys and girls. We have accounted for biological age differences and developed norm-referenced values that can be used to interpret handgrip assessment scores obtained from school-aged children in Hungary. [ABSTRACT FROM PUBLISHER]

Abstract: While liver cancer rates in the United States are increasing, 5‐year survival is only 17.6%, underscoring the importance of prevention. Physical activity has been associated with lower risk of developing liver cancer, but most studies assess physical activity only at a single point in time, often in midlife. We utilized physical activity data from 296,661 men and women in the NIH‐AARP Diet and Health Study cohort to test whether physical activity patterns over the life course could elucidate the importance of timing of physical activity on liver cancer risk. We used group modeling of longitudinal data to create physical activity trajectories using four time points across the life course from teenage years through middle age, identifying seven distinct trajectories. We then used Cox proportional hazards regression to assess the association between the physical activity trajectories and risk of hepatocellular carcinoma, the most common type of liver cancer. We found that, in adjusted analyses, compared to those with consistently low physical activity patterns, those who maintained activity levels over time had a 26–36% lower risk of liver cancer and those who increased physical activity over time had no associations with risk, while those who decreased activity over time had a nonsignificantly higher risk of liver cancer. Our results suggest that sustained physical activity is associated with lower risk of hepatocellular carcinoma, while increasing physical activity later in life may not yield the same benefit. Future research with larger sample sizes and more detailed data on dose and timing of physical activity may continue to yield insight into this association between physical activity and liver cancer risk. [ABSTRACT FROM AUTHOR]

Statistical equivalence testing is more appropriate than conventional tests of difference to assess the validity of physical activity (PA) measures. This article presents the underlying principles of equivalence testing and gives three examples from PA and fitness assessment research.The three examples illustrate different uses of equivalence tests. Example 1 uses PA data to evaluate an activity monitor's equivalence to a known criterion. Example 2 illustrates the equivalence of two field-based measures of physical fitness with no known reference method. Example 3 uses regression to evaluate an activity monitor's equivalence across a suite of 23 activities.The examples illustrate the appropriate reporting and interpretation of results from equivalence tests. In the first example, the mean criterion measure is significantly within ±15% of the mean PA monitor. The mean difference is 0.18 METs and the 90% confidence interval of -0.15 to 0.52 is inside the equivalence region of -0.65 to 0.65. In the second example, we chose to define equivalence for these two measures as a ratio of mean values between 0.98 and 1.02. The estimated ratio of mean ...O2 values is 0.99, which is significantly (P = 0.007) inside the equivalence region. In the third example, the PA monitor is not equivalent to the criterion across the suite of activities. The estimated regression intercept and slope are -1.23 and 1.06. Neither confidence interval is within the suggested regression equivalence regions.When the study goal is to show similarity between methods, equivalence testing is more appropriate than traditional statistical tests of differences (e.g., ANOVA and t-tests). [ABSTRACT FROM AUTHOR]

Background: The utility of self-report measures of physical activity (PA) in youth can be greatly enhanced by calibrating self-report output against objectively measured PA data.This study demonstrates the potential of calibrating self-report output against objectively measured physical activity (PA) in youth by using a commonly used self-report tool called the Physical Activity Questionnaire (PAQ).Methods: A total of 148 participants (grades 4 through 12) from 9 schools (during the 2009-2010 school year) wore an Actigraph accelerometer for 7 days and then completed the PAQ. Multiple linear regression modeling was used on 70% of the available sample to develop a calibration equation and this was cross validated on an independent sample of participants (30% of sample).Results: A calibration model with age, gender, and PAQ scores explained 40% of the variance in values for the percentage of time in moderate-to-vigorous PA (%MVPA) measured from the accelerometers (%MVPA = 14.56 - (sex*0.98) - (0.84*age) + (1.01*PAQ)). When tested on an independent, hold-out sample, the model estimated %MVPA values that were highly correlated with the recorded accelerometer values (r = .63) and there was no significant difference between the estimated and recorded activity values (mean diff. = 25.3 ± 18.1 min; p = .17).Conclusions: These results suggest that the calibrated PAQ may be a valid alternative tool to activity monitoring instruments for estimating %MVPA in groups of youth. [ABSTRACT FROM AUTHOR]

Background: A limitation of traditional outcome studies from behavioral interventions is the lack of attention given to evaluating the influence of moderating variables. This study examined possible moderation effect of baseline activity levels on physical activity change as a result of the Ready for Recess intervention.Methods: Ready for Recess (August 2009-September 2010) was a controlled trial with twelve schools randomly assigned to one of four conditions: control group, staff supervision, equipment availability, and the combination of staff supervision and equipment availability. A total of 393 children (181 boys and 212 girls) from grades 3 through 6 (8-11 years old) were asked to wear an Actigraph monitor during school time on 4-5 days of the week. Assessments were conducted at baseline (before intervention) and post intervention (after intervention).Results: Initial MVPA moderated the effect of Staff supervision (β = -0.47%; p < .05), but not Equipment alone and Staff + Equipment (p > .05). Participants in the Staff condition that were 1 standard deviation (SD) below the mean for baseline MVPA (classified as "low active") had lower MVPA levels at post-intervention when compared with their low active peers in the control condition (Mean diff = -10.8 ± 2.9%; p = .005). High active individuals (+1SD above the mean) in the Equipment treatment also had lower MVPA values at post-intervention when compared with their highly active peers in the control group (Mean diff = -9.5 ± 2.9%; p = .009).Conclusions: These results indicate that changes in MVPA levels at post-intervention were reduced in highly active participants when recess staff supervision was provided. In this study, initial MVPA moderated the effect of Staff supervision on children's MVPA after 6 months of intervention. Staff training should include how to work with inactive youth but also how to assure that active children remain active. [ABSTRACT FROM AUTHOR]

Introduction: Accurate tracking of physical activity (PA) and sedentary behavior (SB) is important to advance public health, but little is known about how to interpret wrist-worn accelerometer data. This study compares youth estimates of SB and moderate to vigorous PA (MVPA) obtained using raw and count-based processing methods.Methods: Data were collected between April and October 2014 for the National Cancer Institute's Family Life, Activity, Sun, Health, and Eating Study: a cross-sectional Internet-based study of youth/family cancer prevention behaviors. A subsample of 628 adolescents (aged 12-17 years) wore the ActiGraph GT3X+ on the wrist for 7 days. In 2015-2016, SB and MVPA time were calculated from raw data using R-package GGIR and from activity counts data using published cutpoints (Crouter and Chandler). Estimates were compared across age, sex, and weight status to examine the impact of processing methods on behavioral outcomes.Results: ActiGraph data were available for 408 participants. Large differences in SB and MVPA time were observed between processing methods, but age and gender patterns were similar. Younger children (aged 12-14 years) had lower sedentary time and greater MVPA time (p-values <0.05) than older children (aged 15-17 years), consistent across methods. The proportion of youth with ≥60 minutes of MVPA/day was highest with the Crouter methods (~50%) and lowest with GGIR (~0%).Conclusions: Conclusions about youth PA and SB are influenced by the wrist-worn accelerometer data processing method. Efforts to harmonize processing methods are needed to promote standardization and facilitate reporting of monitor-based PA data. [ABSTRACT FROM AUTHOR]

This article describes the conceptual design and evaluation strategies used in the NFL PLAY 60 FITNESSGRAM® Partnership Project, a large participatory research network focused on building effective school physical education programming. The article summarizes the unique participatory design, recruitment methods, programming strategies, and analytical plans used to evaluate this large project. The study provides unique insight into how to effectively deliver large-scale school-based physical fitness and physical activity programming to support and enhance physical education programming in schools. [ABSTRACT FROM PUBLISHER]

Background: The national physical activity guidelines (PAG) in many countries recommend that youth accumulate 60 min or more of moderate-to-vigorous physical activity (MVPA) daily (PAG-MVPA). A daily target of ≥ 11,500 steps/day has been proposed as a step count alternative to this guideline (PAG-Steps). Contemporary activity monitors are capable of estimating both MVPA and steps, but it is not clear how these units compare when used to evaluate compliance with the national PAG. The purpose of this study was to compare prevalence estimates of meeting the PAG-MVPA and PAG-Steps using two commonly used monitors, the ActiGraph (AG) and SenseWear Armband (SWA).Methods: A sample of 69 children (25 girls and 44 boys) aged 9-16 years each wore a wrist-mounted AG and a SWA over a one-week period. Days with ≥10 h of wear time for both monitors were included in the analysis. Estimates of time spent in MVPA were obtained using the Crouter equation for the AG and from proprietary algorithms for the SWA. Step counts for the AG and SWA were directly obtained from the respective software. The prevalence of meeting the PAG-MVPA and PAG-Steps was compared within each monitor, using Cohen's kappa (κ) statistic. Agreement was similarly assessed between monitors using each guideline individually.Results: When assessed with the AG, the prevalence of meeting PAG was substantially higher for the PAG-MVPA (87.2 %) than for the PAG-Steps (54.2 %), with fair classification agreement (κ = 0.30) between the two guidelines. Higher prevalence rates were also observed for the PAG-MVPA (83.6 %) than for the PAG-Steps (33.8 %) when assessed using the SWA, but the prevalence rates and classification agreement (κ = 0.18) were lower than the values from the AG. Classification agreement between AG and SWA was lower for the PAG-MVPA (κ = 0.42) than for the PAG-Steps (κ = 0.55).Conclusions: The results show differential patterns of compliance with the PAG-MVPA and PAG-Steps, as assessed by the AG and SWA. Additional research is needed to directly evaluate and compare findings from public health research based on different guidelines and measurement methods. [ABSTRACT FROM AUTHOR]

Background. Accelerometers can provide accurate estimates of moderate-to-vigorous physical activity (MVPA). However, one of the limitations of these instruments is the inability to capture light activity within an acceptable range of error. The purpose of the present study was to determine the validity of different activity monitors for estimating energy expenditure (EE) of light intensity, semi-structured activities. Methods. Forty healthy participants wore a SenseWear Pro3 Armband (SWA, v.6.1), the SenseWear Mini, the Actiheart, ActiGraph, and ActivPAL monitors, while being monitored with a portable indirect calorimetry (IC). Participants engaged in a variety of low intensity activities but no formalized scripts or protocols were used during these periods. Results. The Mini and SWA overestimated total EE on average by 1.0% and 4.0%, respectively, while the AH, the GT3X, and the AP underestimated total EE on average by 7.8%, 25.5%, and 22.2%, respectively. The pattern-recognition monitors yielded non-significant differences in EE estimates during the semi-structured period (p = 0.66, p = 0.27, and p = 0.21 for the Mini, SWA, and AH, respectively). Conclusions. The SenseWear Mini provided more accurate estimates of EE during light to moderate intensity semi-structured activities compared to other activity monitors. This monitor should be considered when there is interest in tracking low intensity activities in groups of individuals. [ABSTRACT FROM AUTHOR]

Background: The 24-h rest and activity behaviors (i.e., physical activity, sedentary behaviors and sleep) are fundamental human behaviors essential to health and well-being. Functional principal component analysis (fPCA) is a flexible approach for characterizing rest-activity rhythms and does not rely on a priori assumptions about the activity shape. The objective of our study is to apply fPCA to a nationally representative sample of American adults to characterize variations in the 24-h rest-activity pattern, determine how the pattern differs according to demographic, socioeconomic and work characteristics, and examine its associations with general health status. Methods: The current analysis used data from adults 25 or older in the National Health and Nutrition Examination Survey (NHANES, 2011–2014). Using 7-day 24-h actigraphy recordings, we applied fPCA to derive profiles for overall, weekday and weekend rest-activity patterns. We examined the association between each rest-activity profile in relation to age, gender, race/ethnicity, education, income and working status using multiple linear regression. We also used multiple logistic regression to determine the relationship between each rest-activity profile and the likelihood of reporting poor or fair health. Results: We identified four distinct profiles (i.e., high amplitude, early rise, prolonged activity window, biphasic pattern) that together accounted for 86.8% of total variation in the study sample. We identified numerous associations between each rest-activity profile and multiple sociodemographic characteristics. We also found evidence suggesting the associations differed between weekdays and weekends. Finally, we reported that the rest-activity profiles were associated with self-rated health. Conclusions: Our study provided evidence suggesting that rest-activity patterns in human populations are shaped by multiple demographic, socioeconomic and work factors, and are correlated with health status. [ABSTRACT FROM AUTHOR]

Considerable public health efforts across the globe have focused on promoting physical activity (PA) and minimizing sedentary behaviour (SB) in youths. However, it is important to have valid, reliable and feasible methods to assess these behaviours in youths. The purpose of this study was to analyse the feasibility and reliability of the Spanish version of the previously validated Youth Activity Profile questionnaire (YAP) in children and adolescents. The YAP-S is a 15-item self-report instrument designed to capture PA and SB in youths. A total of 604 children (5–12 years old) and 346 adolescents (12–17 years old) filled out the questionnaire twice (14 days apart). Feasibility was evaluated through required time and number of misunderstood questions by participants. The test-retest reliability was examined using the weighted kappa coefficient (κ) and intraclass correlation coefficient. The average time to complete the questionnaire was 28.85 ± 14.28 and 12.24 ± 9.84 minutes in children and adolescents, respectively. No misunderstanding of questions was reported. The questionnaire showed an adequate reliability for activity at school, out-of-school and sedentary behaviours (k = 0.61–0.77; ICC = 0.77–0.89) in children and adolescents. The YAP-S might be considered a feasible and reliable questionnaire for assessing PA and SB in Spanish children and adolescents. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Purpose: Confounding due to poor health is a concern in accelerometer-based studies of physical activity and health, but detailed investigations of this source of bias are lacking. Methods: US adults (n = 4840) from the National Health and Nutrition Examination Survey (2003 to 2006) wore an accelerometer for 1 to 7 d (mean = 5.7 d) and were followed for mortality through 2015. Logistic regression was used to examine odds ratios between poor health (chronic conditions, self-reported health, mobility limitations, frailty) and low physical activity levels; Cox models were used to estimate adjusted hazard ratios (HR) and 95% CI for mortality associations for a 1 h·d−1 increase in moderate-to-vigorous–intensity physical activity (MVPA) using two commonly used cut-points (MVPA760, MVPA2020). Modeling scenarios with shorter and longer follow-up time, increasing adjustment for poor health, by age group, and after excluding early years of follow-up were used to assess bias. Results: Over a mean of 10.1 yr of follow-up, 1165 deaths occurred. Poor health was associated with low MVPA760 levels and increased mortality risk. In fully adjusted MVPA760 models, HR was 26% stronger comparing 0 to 4 yr (HR = 0.46) with 0 to 12 yr of follow-up (HR = 0.62), particularly in older adults (65 yr and older). Increasing statistical adjustment for poor health attenuated MVPA760 associations by 13% to 15%, and exclusion of the first 2 yr of follow-up had limited effects. Comparable results were obtained with the MVPA2020 cut-point. Conclusions: We did not find evidence that confounding by health status resulted in entirely spurious MVPA–mortality associations; however, potential bias was appreciable in modeling scenarios involving shorter follow-up (<6 yr), older adults, and more limited statistical adjustment for poor health. The strength of MVPA–mortality associations in studies reflecting these scenarios should be interpreted cautiously. [ABSTRACT FROM AUTHOR]

Background: Due to the high prevalence of obesity and the difficulty in maintaining weight loss, repeated bouts of weight loss are a common occurrence. However, there are inconsistencies in epidemiological studies regarding repetitive weight fluctuations being associated with increased risk of mortality. Therefore, the purpose of this prospective cohort analysis was to determine the long-term association of the frequency of weight loss attempts on mortality.Methods: This prospective cohort study used data collected from adult AARP members living in 6 states (California, Florida, Louisiana, New Jersey, North Carolina, or Pennsylvania) or 2 metropolitan areas (Atlanta, Georgia, or Detroit, Michigan) and participating in the National Institutes of Health-AARP Diet and Health Study between 2004 and 2006. Self-reported data were analyzed for 161,738 middle-aged adults. During an average 7 years of follow-up, 21,194 deaths were recorded. Hazard ratios of all-cause, cardiovascular, and cancer mortality were estimated adjusting for demographic, lifestyle, and behavioral risk factors.Results: Increased frequency of weight loss attempts of at least five pounds was associated with lower mortality (ptrend < 0.010). Multivariate hazard ratios (95% confidence intervals) for all-cause death among individuals who successfully attempted weight loss compared with those who did not make any attempts were 0.94 (0.90-0.98) for 1-2 attempts, 0.96 (0.91-1.01) for 3-4 attempts, 0.91 (0.85-0.96) for 5-6 attempts, 0.91 (0.85-0.98) for 7-8 attempts, 0.87 (0.80-0.95) for 9-10 attempts, and 0.88 (0.82-0.94) for 11+ attempts. Similar results were noted for men and women, participants with healthy weight and overweight/obesity, and even among those who gained weight over time. Protective associations were also observed for deaths due to cardiovascular disease and cancer.Conclusions: Increased frequency of intentionally losing at least five pounds in mid-life was associated with a lower risk of future death. Repeated attempts with moderate amounts of weight loss may provide benefit in terms of longevity.Trial Registration Number: ClinicalTrials.gov number, NCT00340015. [ABSTRACT FROM AUTHOR]

This study used accelerometer and self-report measures of overall sedentary time (ST) and screen time behaviours to examine their respective associations with adiposity among UK youth. Participants (Year groups 5, 8, and 10; n=292, 148 girls) wore the SenseWear Armband Mini accelerometer for eight days and completed the Youth Activity Profile, an online report tool designed to estimate physical activity and ST.Stature, body mass and waist circumference were measured to classify adiposity outcomes (overweight/obese and central obesity). One-way between groups ANOVA and adjusted linear, logistic and multinomial logistic regression analyses were conducted. There was a significant main effect of age on total ST across the whole week (F(2, 289)=41.64, p≤0.001). ST increased monotonically across Year 5 (581.09±107.81 min·dˉ¹), 8 (671.96±112.59 min·dˉ¹) and 10 (725.80±115.20 min·dˉ¹), and all pairwise comparisons were significant at p≤0.001. A steep age-related gradient to mobile phone use was present (p≤0.001). ST was positively associated with adiposity outcomes independent of moderate-to-vigorous intensity physical activity (MVPA; p≤0.001). Engaging in >3 hours of video gaming daily was positively associated with central obesity (OR=2.12, p≤0.05) but not after adjustment for MVPA. Results further demonstrate the importance of reducing overall ST to maintain healthy weight status among UK youth. [ABSTRACT FROM AUTHOR]