Criterion validity of the activPAL™ and ActiGraph for assessing children's sitting and standing time in a school classroom setting.

BACKGROUND: Few studies have investigated the accuracy of the ActiGraph (AG) GTX3 accelerometer for assessing children's sitting and standing time. The activPAL (aP) has an inclinometer function that enables it to distinguish between sitting/lying and standing; however, its accuracy for assessing sitting and standing in older children is unknown. This study validated the accuracy of these devices for estimating sitting and standing time in a school classroom against a criterion measure of direct observation (DO). FINDINGS: Forty children in grades 5-7 wore both devices while being video recorded during two school lessons. AG and aP data were simultaneously collected in 15-s epochs. Individual participant DO and aP data were recorded as total time spent sitting/lying, standing and stepping. AG data were converted into time spent sitting and standing using previously established cut-points. Compared with DO, the aP underestimated sitting time (mean bias = -1.9 min, 95 % LoA = -8.9 to 5.2 min) and overestimated standing time (mean bias = 1.8 min, 95% LoA = -9.6 to 13.3 min). The best-performing AG cut-point across both sitting and standing (<75 counts/15 s) was more accurate than the aP, underestimating sitting time (mean bias = -0.8 min, 95 % LoA = -10.5 to 9.9 min) and standing time (mean bias = -0.4 min, 95% LoA = -9.8 to 9.1 min), but was less precise as evidenced by wider LoAs and poorer correlations with DO (sitting r = 0.86 aP vs 0.80 AG; standing r = 0.78 aP vs 0.60 AG). CONCLUSIONS: The aP demonstrated good accuracy and precision for assessing free-living sitting and standing time in classroom settings. The AG was most accurate using a cut-point of < 75 counts/15 s. Further studies should validate the monitors in settings with greater inter- and intra-individual variation in movement patterns.

Physical activity and sedentary behaviour among Asian and Anglo-Australian adolescents.

ISSUE ADDRESSED: Evidence suggests that physical activity (PA) and sedentary behaviour (SB) participation varies among culturally and linguistically diverse (CALD) adolescents. The present study examined differences in PA and SB among a CALD sample of Chinese Australian, South-east Asian and Anglo-Australian adolescents. METHODS: Data from 286 adolescents aged 12-16 years involved in the Chinese and Australian Adolescent Health Survey in metropolitan Melbourne, Australia, were analysed. Accelerometry outcomes included median activity counts per minute (counts x min(-1)) and minutes per day (min x day(-1)) spent in light-intensity PA (LPA), moderate-to-vigorous-intensity PA (MVPA) and sedentary time (ST). Kruskal-Wallis one-way analysis of variance and sequential multiple hierarchical linear regressions were used to examine CALD differences in PA and ST. RESULTS: Multivariate analyses of accelerometry data found Chinese Australian and South-east Asian adolescents engaged in significantly less daily MVPA (5-8 min x day(-1)) and LPA (50-58 min x day(-1); P < 0.05), but greater daily ST (40-41 min x day(-1)), than Anglo-Australian adolescents, after adjusting for age, gender and socioeconomic category. CONCLUSION: The results demonstrate lower engagement in daily MVPA and LPA and greater engagement in ST using accelerometry among Chinese Australian and South-east Asian adolescents compared with Anglo-Australian adolescents. These findings have important public health implications in furthering our understanding of CALD differences in PA and SB. SO WHAT? An understanding of the CALD differences in physical activity and sedentary behaviour among Australian adolescents has important implications for intervention planning and delivery as well as the wider health implications of these behaviours. This article furthers the current understanding of CALD adolescents' participation in physical activity and sedentary behaviour, of which limited information is available.

Reliability and validity of the modified Child and Adolescent Physical Activity and Nutrition Survey (CAPANS-C) questionnaire examining potential correlates of physical activity participation among Chinese-Australian youth.

BACKGROUND: To date, few questionnaires examining psychosocial influences of physical activity (PA) participation have been psychometrically tested among Culturally and Linguistically Diverse (CALD) youth. An understanding of these influences may help explain the observed differences in PA among CALD youth. Therefore, this study examined the reliability and predictive validity of a brief self-report questionnaire examining potential psychological and social correlates of physical activity among a sample of Chinese-Australian youth. METHODS: Two Chinese-weekend cultural schools from eastern metropolitan Melbourne consented to participate in this study. In total, 505 students aged 11 to 16 years were eligible for inclusion in the present study, and of these, 106 students agreed to participate (21% response rate). Participants completed at 37-item self-report questionnaire examining perceived psychological and social influences on physical activity participation twice, with a test-retest interval of 7 days. Predictive validity, internal consistency and test-retest reliability were evaluated using exploratory factor analyses, Cronbach's α coefficient, and the intraclass correlation coefficient (ICC) respectively. Predictive validity was assessed by correlating responses against duration spent in self-reported moderate-to-vigorous physical activity (MVPA). RESULTS: The exploratory factor analysis revealed a nine factor structure, with the majority of factors exhibiting high internal consistency (α ≥ 0.6). In addition, four of the nine factors had an ICC ≥ 0.6. Spearman rank-order correlations coefficients between the nine factors and self-reported minutes spent in MVPA ranged from -0.5 to 0.3 for all participants. CONCLUSION: This is the first study to examine the psychometric properties of a potential psychological and social correlates questionnaire among Chinese-Australian youth. The questionnaire was found to provide reliable estimates on a range of psychological and social influences on physical activity and evidence of predictive validity on a limited number of factors. More research is required to improve the reliability and validity of the questionnaire.

Development and psychometric properties of the Y-PASS questionnaire to assess correlates of lunchtime and after-school physical activity in children.

BACKGROUND: To frame interventions, it is useful to understand context- and time-specific correlates of children's physical activity. To do this, we need accurate assessment of these correlates. There are currently no measures that assess correlates at all levels of the social ecological model, contain items that are specifically worded for the lunchtime and/or after-school time periods, and assess correlates that have been conceptualised and defined by children. The aim of this study was to develop and evaluate the psychometric properties of the lunchtime and after-school Youth Physical Activity Survey for Specific Settings (Y-PASS) questionnaires. METHODS: The Y-PASS questionnaire was administered to 264 South Australian children (146 boys, 118 girls; mean age = 11.7 ± 0.93 years). Factorial structure and internal consistency of the intrapersonal, sociocultural and physical environmental/policy lunchtime and after-school subscales were examined through an exploratory factor analysis. The test-retest reliability of the Y-PASS subscales was assessed over a one-week period on a subsample of children (lunchtime Y-PASS: n = 12 boys, 12 girls, mean age of 11.6 ± 0.8 years; after-school Y-PASS: n = 9 boys, 13 girls; mean age = 11.4 ± 0.9 years). RESULTS: For the lunchtime Y-PASS, three factors were identified under each of the intrapersonal, sociocultural and physical environmental/policy subscales. For the after-school Y-PASS, six factors were identified in the intrapersonal subscale, four factors in the sociocultural subscale and seven factors in the physical environmental/policy subscale. Following item reduction, all subscales demonstrated acceptable internal consistency (Cronbach alpha = 0.78-0.85), except for the lunchtime sociocultural subscale (Cronbach alpha = 0.55). The factors and items demonstrated fair to very high test-retest reliability (ICC = 0.26-0.93). CONCLUSION: The preliminary reliability and factorial structure evidence suggests the Y-PASS correlate questionnaires are robust tools for measuring correlates of context-specific physical activity in children. The multi-dimensional factor structure provides justification for exploring physical activity correlates from a social ecological perspective and demonstrates the importance of developing items that are context specific. Further development and refinement of the Y-PASS questionnaires is recommended, including a confirmatory factor analysis and exploring the inclusion of additional items.

Validating the multimedia activity recall for children and adolescents in a large New Zealand sample.

The aim of the study was to validate the self-report Multimedia Activity Recall for Children and Adolescents (MARCA) against accelerometry for the assessment of physical activity in New Zealand children. Participants (n = 716, 10-18 years) recalled 3-4 days of activity using the MARCA and underwent a partially overlapping 7-day accelerometry protocol during a national survey. Spearman correlation coefficients (ρ) assessed the association between accelerometer-derived counts per minute and MARCA-derived physical activity level and time in locomotion. Both data sources estimated time spent in light and moderate-vigorous physical activity. Association and agreement between methods for light physical activity and moderate-vigorous physical activity was assessed using correlations and Bland-Altman plots respectively, and paired t-tests conducted. Accelerometer-derived activity counts were moderately correlated with both MARCA-derived physical activity level and locomotion (ρ = 0.38, P < 0.0001). The correlation between methods was -0.14 for light physical activity and 0.28 for moderate-vigorous physical activity (P < 0.0001). The MARCA overestimated moderate-vigorous physical activity compared with accelerometry (120 min, P < 0.0001), which increased as moderate-vigorous physical activity time increased. Some sex and ethnicity (Maori [indigenous] versus non-Maori) differences were observed. Overall, the MARCA indicated moderate validity for assessment of physical activity level, locomotion and moderate-vigorous physical activity and poor validity for assessment of light physical activity. This was comparable to other self-report tools. The MARCA has utility for future large-scale research.

Exploring Medical Student Attitudes Regarding Inter-university Learning: A Pilot Study.

Introduction The United Kingdom needs to educate more medical students to meet workforce demands. With static numbers of clinical teachers available, novel and efficient approaches are required to prepare students for real-life work where doctors routinely work with colleagues from different medical schools. This innovative project was designed to investigate student attitudes towards inter-university learning (IUL), whereby two medical students from different universities learn together. Materials and methods Thirteen students at Great Western Hospital, Swindon, England, volunteered and were randomly paired with a student from another university. Pairs completed a 20-minute simulated clinical scenario and observed three others. Students completed pre- and post-session questionnaires adapted from the Readiness for Inter-Professional Learning scale. Seven students took part in semi-structured interviews which underwent thematic analysis. Results Quantitative analysis of post-session questionnaires demonstrated a positive response to IUL. Thematic analysis generated six themes: impact on learning, impact on career, working together, recognising differences, practical considerations, and psychosocial perspectives. Discussion Students enjoyed the social learning opportunity to practise team-working, communication, and role delegation with unknown peers whilst sharing different clinical approaches. Differences in course structure meant students displayed varying strengths, although unexpected findings centred around pre-conceptions of both universities and social comparison behaviours. Conclusion IUL's strength was deemed to be in non-technical skill development to prepare for real-life work, ultimately enhancing patient safety. Practicalities to consider include session design and psychological safety. IUL provides a novel solution to efficiently educate future healthcare professionals and further work to explore its benefits on a wider scale is suggested.

Correlates of children's time-specific physical activity: a review of the literature.

Assessment of correlates of physical activity occurring at different times of the day, locations and contexts, is imperative to understanding children's physical activity behaviour. The purpose of this review was to identify the correlates of children's physical activity (aged 8-14 years) occurring during the school break time and after-school periods. A review was conducted of the peer-reviewed literature, published between 1990 and January 2011. A total of 22 studies (12 school break time studies, 10 after-school studies) were included in the review. Across the 22 studies, 17 studies were cross-sectional and five studies were interventions. In the school break time studies, 39 potential correlates were identified, of which gender and age were consistently associated with school break time physical activity in two or more studies, and family affluence, access to a gym, access to four or more physical activity programs and the condition of a playing field were all associated with school break time physical activity in only one study. Access to loose and fixed equipment, playground markings, size of and access to play space and the length of school break time were all positively associated with changes in school break time physical activity in intervention studies. Thirty-six potential correlates of after-school physical activity were identified. Gender (with boys more active), younger age, lower body mass index (for females), lower TV viewing/playing video games, and greater access to facilities were associated with higher levels of after-school physical activity in two or more studies. Parent supervision was negatively associated with females' after-school physical activity in one study. This review has revealed a relatively small number of studies investigating the school break time and after-school periods in the specified age range and only a few correlates have demonstrated a consistent association with physical activity. This highlights the infancy of this area and a need for further investigation into time-specific physical activity behaviour so that interventions designed for these specific periods can target the important correlates.

Agreement between activPAL and ActiGraph for assessing children's sedentary time.

BACKGROUND: Accelerometers have been used to determine the amount of time that children spend sedentary. However, as time spent sitting may be detrimental to health, research is needed to examine whether accelerometer sedentary cut-points reflect the amount of time children spend sitting. The aim of this study was to: a) examine agreement between ActiGraph (AG) cut-points for sedentary time and objectively-assessed periods of free-living sitting and sitting plus standing time using the activPAL (aP); and b) identify cut-points to determine time spent sitting and sitting plus standing. METHODS: Forty-eight children (54% boys) aged 8-12 years wore a waist-mounted AG and thigh-mounted aP for two consecutive school days (9-3:30 pm). AG data were analyzed using 17 cut-points between 50-850 counts·min-1 in 50 counts·min-1 increments to determine sedentary time during class-time, break time and school hours. Sitting and sitting plus standing time were obtained from the aP for these periods. Limits of agreement were computed to evaluate bias between AG50 to AG850 sedentary time and sitting and sitting plus standing time. Receiver Operator Characteristic (ROC) analyses identified AG cut-points that maximized sensitivity and specificity for sitting and sitting plus standing time. RESULTS: The smallest mean bias between aP sitting time and AG sedentary time was AG150 for class time (3.8 minutes), AG50 for break time (-0.8 minutes), and AG100 for school hours (-5.2 minutes). For sitting plus standing time, the smallest bias was observed for AG850. ROC analyses revealed an optimal cut-point of 96 counts·min-1 (AUC = 0.75) for sitting time, which had acceptable sensitivity (71.7%) and specificity (67.8%). No optimal cut-point was obtained for sitting plus standing (AUC = 0.51). CONCLUSIONS: Estimates of free-living sitting time in children during school hours can be obtained using an AG cut-point of 100 counts·min-1. Higher sedentary cut-points may capture both sitting and standing time.

It's not just the television: survey analysis of sedentary behaviour in New Zealand young people.

BACKGROUND: Sedentary behaviour has been linked with adverse health outcomes in young people; however, the nature and context of being sedentary is poorly understood. Accurate quantification and description of sedentary behaviour using population-level data is required. The aim of this research was to describe sedentary behaviour among New Zealand (NZ) youth and examine whether sedentary behaviour differs by Body Mass Index (BMI) status in this population. METHODS: A national representative cross-sectional survey of young people aged 5-24 years (n = 2,503) was conducted in 2008-2009. Data from this survey, which included subjectively (recall diary; n = 1,309) and objectively (accelerometry; n = 960) measured sedentary behaviour for participants aged 10-18 years were analysed using survey weighted methods. RESULTS: Participants self-reported spending on average 521 minutes per day (standard error [SE] 5.29) in total sedentary behaviour, 181 minutes per day (SE 3.91) in screen-based sedentary activities (e.g., television and video games), and 340 minutes per day (SE 5.22) in other non-screen sedentary behaviours (e.g., school, passive transport and self-care). Accelerometer-measured total sedentary behaviour was on average 420 minutes per day (SE 4.26), or 53% (SE 0.42%) of monitored time. There were no statistically significant differences in time spent in sedentary behaviour among overweight, obese and healthy/underweight young people. CONCLUSIONS: Both subjective and objective methods indicate that NZ youth spend much of their waking time being sedentary. No relationships were found between sedentary behaviour and BMI status. These findings extend previous research by describing engagement in specific sedentary activities, as well as quantifying the behaviour using an objective method. Differences in what aspects of sedentary behaviour the two methods are capturing are discussed. This research highlights the potential for future interventions to target specific sedentary behaviours or demographic groups.

Reliability of the modified child and adolescent physical activity and nutrition survey, physical activity (CAPANS-PA) questionnaire among Chinese-Australian youth.

BACKGROUND: Evidence suggests that differences exist in physical activity (PA) participation among Culturally and Linguistically Diverse (CALD) children and adolescents. It is possible that these differences could be influenced by variations in measurement technique and instrument reliability. However, culturally sensitive instruments for examining PA behaviour among CALD populations are lacking. This study tested the reliability of the Child and Adolescent Physical Activity and Nutrition Survey (CAPANS-PA) recall questionnaire among a sample of Chinese-Australian youth. METHODS: The psychometric property of the CAPANS-PA questionnaire was examined among a sample of 77 Chinese-Australian youth (aged 11-14 y) who completed the questionnaire twice within 7 days. Test-retest reliability of individual items and scales within the CAPANS-PA questionnaire was determined using Kappa statistics for categorical variables and intraclass correlation coefficients (ICC) for continuous variables. RESULTS: The CAPANS-PA questionnaire demonstrated acceptable test-retest reliability for frequency and duration of time spent in weekly Moderate to Vigorous Physical Activity (MVPA) (ICC ≥ 0.70) for all participants. Test-retest reliability for time spent in weekly sedentary activities was acceptable for females (ICC = 0.82) and males (ICC = 0.72). CONCLUSIONS: The results suggest the CAPANS-PA questionnaire provides reliable estimates for type, frequency and duration of MVPA participation among Chinese-Australian youth. Further investigation into the reliability of the sedentary items within the CAPANS-PA is required before these items can be used with confidence. This study is novel in that the reliability of instruments among CALD groups nationally and internationally remains sparse and this study contributes to the wider body of available psychometrically tested instruments. In addition, this study is the first to our knowledge to successfully engage and investigate the basic health enhancing behaviours of Chinese-Australian adolescents.

Descriptive epidemiology of screen and non-screen sedentary time in adolescents: a cross sectional study.

BACKGROUND: Much attention has been paid to adolescents' screen time, however very few studies have examined non-screen sedentary time (NSST). This study aimed to (1) describe the magnitude and composition of screen sedentary time (SST) and NSST in Australian adolescents, (2) describe the socio-demographic correlates of SST and NSST, and (3) determine whether screen time is an adequate surrogate for total sedentary behaviour in this population. METHODS: 2200 9-16 year old Australians provided detailed use of time data for four days. Non-screen sedentary time (NSST) included time spent participating in activities expected to elicit <3 METs whilst seated or lying down (other than sleeping), excluding screen-based activities (television, playing videogames or using computers). Total sedentary time was the sum of screen time and NSST. RESULTS: Adolescents spent a mean (SD) of 345 (105) minutes/day in NSST, which constituted 60% of total sedentary time. School activities contributed 42% of NSST, socialising 19%, self-care (mainly eating) 16%, and passive transport 15%. Screen time and NSST showed opposite patterns in relation to key socio-demographic characteristics, including sex, age, weight status, household income, parental education and day type. Because screen time was negatively correlated with NSST (r = -0.58), and exhibited a moderate correlation (r = 0.53) with total sedentary time, screen time was only a moderately effective surrogate for total sedentary time. CONCLUSIONS: To capture a complete picture of young people's sedentary time, studies should endeavour to measure both screen time and NSST.

Intra-individual variation in children's physical activity patterns: Implications for measurement.

Children's physical activity (PA) patterns change from day to day. This intra-individual variability affects precision when measuring key physical activity and sedentary behaviour variables. This paper discusses strategies used to reduce the random error associated with intra-individual variability and demonstrates the implications for assessing PA when varying number of days are sampled. Self-reported data collected on two hundred and ninety eight 13-14-year-olds were used to compare estimates of PA and sedentary behaviour derived from between 1 and 7 days of recall data. Large intra-individual coefficients of variation were calculated for physical activity level (14.5%), moderate-to-vigorous physical activity (83.4%), screen time (60.8%) and sleep (12.2%). While the magnitude of error associated with estimating means decreased as more days were sampled, the paper notes that depending on the nature of the research question being asked, sampling fewer days may yield sufficiently precise estimates. Therefore, researchers should conduct power analyses based on estimated inter- and intra-individual variability and sample size to determine how many days to sample when assessing children's PA patterns.

Changes in Physical Activity Behaviour and Psychosocial Correlates Unique to the Transition from Primary to Secondary Schooling in Adolescent Females: A Longitudinal Cohort Study.

Few studies have investigated physical activity changes over the transition from primary to secondary school. This study assessed change in physical activity and the psychosocial correlates across 12 months in two cohorts of adolescent girls, who were either in primary school in year 1, moving to secondary school in year 2 (Transition cohort) or an older cohort (Secondary cohort) who remained in early secondary school. Female adolescents (n = 191; 38% response rate) in South Australia self-reported physical activity and psychosocial correlates of physical activity. Changes between baseline and 12-month follow-up were assessed using paired t-tests. Multiple regression modelling identified psychosocial predictors of physical activity change. Physical activity declined in the transition but not the secondary cohort. The decline was most pronounced during school break times. Independent predictors of physical activity change were: change in enjoyment in the transition cohort; and changes in enjoyment, perceived outcomes, and friend encouragement in the secondary cohort. Transitioning from primary to secondary school is a critical period during which physical activity typically declines, particularly among females. Effective physical activity promotion in this vulnerable group will depend on a deeper understanding of the sociocultural, curricular and environmental influences on physical activity that are unique to each school context.

A source of systematic bias in self-reported physical activity: The cutpoint bias hypothesis.

OBJECTIVES: Estimates of adults' moderate-to-vigorous physical activity (MVPA) based on self-report are generally higher than estimates derived from criterion measures. This study examines a possible explanation for part of this discrepancy: the cutpoint bias hypothesis. This hypothesis proposes that inter- and intra-individual variability in energy expenditure, combined with the fact that adults perform a high proportion of daily activities at or just above the traditional 3 MET cutpoint, result in systematic over-estimates of MVPA. DESIGN: Cross-sectional. METHODS: Time-use recalls (n = 6862) were collected using the Multimedia Activity Recall for Children and Adults from 2210 adults (1215 female, age 16-93 years) from 16 studies conducted in Australia and New Zealand between 2008-2017. Minutes spent in MVPA were estimated using models with varying levels of intra- and inter-individual (total variability) Unadjusted (0% total variability), Low (11.9%), Best Guess (20.7%), and High (30.0%). RESULTS: In the Unadjusted model, participants accumulated an average of 129 (standard deviation 127) min/day of MVPA. Estimated MVPA was 98 (110), 99 (107) and 108 (107) min/day in the Low, Best Guess and High variability models, respectively, with intra-class correlation coefficients with the Unadjusted model ranging from 0.78 to 0.83. CONCLUSIONS: These findings support the hypothesis of a cutpoint bias, which probably contributes to the large disparities seen between self-reported and criterion measures of MVPA. Future studies are needed to confirm these findings using other self-report instruments and in other populations.

Development of a compendium of energy expenditures for youth.

BACKGROUND: This paper presents a Compendium of Energy Expenditures for use in scoring physical activity questionnaires and estimating energy expenditure levels in youth. METHOD/RESULTS: Modeled after the adult Compendium of Physical Activities, the Compendium of Energy Expenditures for Youth contains a list of over 200 activities commonly performed by youth and their associated MET intensity levels. A review of existing data collected on the energy cost of youth performing activities was undertaken and incorporated into the compendium. About 35% of the activity MET levels were derived from energy cost data measured in youth and the remaining MET levels estimated from the adult compendium. CONCLUSION: The Compendium of Energy Expenditures for Youth is useful to researchers and practitioners interested in identifying physical activity and energy expenditure values in children and adolescents in a variety of settings.

Children's physical activity levels during organised sports practices.

OBJECTIVES: This study measured the physical activity levels of children during practice sessions of four popular organised sports in Australia. DESIGN: Cross-sectional observational design. METHODS: Participants comprised children from four local organised sports clubs in suburban Adelaide, South Australia. The sports examined were Australian Rules Football (AFL), girls' netball, boys' soccer and girls' soccer. Each participant wore a waist-mounted GT3X or GT3X+Actigraph accelerometer in either one or two of the practice sessions. RESULTS: Participants typically spent 40-50% of each sport practice session in moderate to vigorous physical activity (MVPA). Participants in the boys' soccer teams spent significantly greater time in MVPA (mean=47% of practice time, 95% CI=37%, 57%) than participants in the girls' netball teams (mean=40%, 95% CI=30%, 50%), participants in the girls' soccer teams (mean=38%, 95% CI=28%, 48%) and participants in the boys' AFL teams (mean=40%, 95% CI=36%, 44%). The practice sessions contributed approximately half of the 60min of MVPA per day recommended by physical activity guidelines for children and young people. CONCLUSIONS: The results suggested that organised sports provide a supportive environment for physical activity accrual; however, one practice session is insufficient for children to reach the amount of MVPA recommended in daily physical activity guidelines.

Utility of the Youth Compendium of Physical Activities.

PURPOSE: The purposes of this article are to: (a) describe the rationale and development of the Youth Compendium of Physical Activities (Youth Compendium); and (b) discuss the utility of the Youth Compendium for audiences in research, education, community, health care, public health, and the private sector. METHODS: The Youth Compendium provides a list of 196 physical activities (PA) categorized by activity types, specific activities, and metabolic costs (youth metabolic equivalents of task [METy]) as measured by indirect calorimetry. The utility of the Youth Compendium was assessed by describing ways in which it can be used by a variety of audiences. RESULTS: Researchers can use METy values to estimate PA levels and determine changes in PA in intervention studies. Educators can ask students to complete PA records to determine time spent in physical activities and to identify health-enhancing activities for classroom PA breaks. Community leaders, parents, and health care professionals can identify activity types that promote healthful behaviors. Public health agencies can use the METy values for surveillance and as a resource to inform progress toward meeting national physical activity guidelines. Applications for the private sector include the use of METy in PA trackers and other applications. CONCLUSION: The National Collaborative on Childhood Obesity Research Web site presents the Youth Compendium and related materials to facilitate measurement of the energy cost of nearly 200 physical activities in children and youth. The Youth Compendium provides a way to standardize energy costs in children and youth and has application for a wide variety of audiences.

A Youth Compendium of Physical Activities: Activity Codes and Metabolic Intensities.

PURPOSE: A Youth Compendium of Physical Activities (Youth Compendium) was developed to estimate the energy costs of physical activities using data on youth only. METHODS: On the basis of a literature search and pooled data of energy expenditure measurements in youth, the energy costs of 196 activities were compiled in 16 activity categories to form a Youth Compendium of Physical Activities. To estimate the intensity of each activity, measured oxygen consumption (V˙O2) was divided by basal metabolic rate (Schofield age-, sex-, and mass-specific equations) to produce a youth MET (METy). A mixed linear model was developed for each activity category to impute missing values for age ranges with no observations for a specific activity. RESULTS: This Youth Compendium consists of METy values for 196 specific activities classified into 16 major categories for four age-groups, 6-9, 10-12, 13-15, and 16-18 yr. METy values in this Youth Compendium were measured (51%) or imputed (49%) from youth data. CONCLUSION: This Youth Compendium of Physical Activities uses pediatric data exclusively, addresses the age dependency of METy, and imputes missing METy values and thus represents advancement in physical activity research and practice. This Youth Compendium will be a valuable resource for stakeholders interested in evaluating interventions, programs, and policies designed to assess and encourage physical activity in youth.

How should activity guidelines for young people be operationalised?

BACKGROUND: If guidelines regarding recommended activity levels for young people are to be meaningful and comparable, it should be clear how they are operationalised. It is usually open to interpretation whether young people are required to meet activity and screen time targets (1) all days of the week, (2) on most days of the week, (3) on average across all days, or (4) whether compliance should be understood as the probability that a randomly selected young person meets the guidelines on a randomly selected day. This paper studies this question using data drawn from the Australian Health of Young Victorians study. METHODS: The subjects for this study were 885 13-19 year olds who recalled four days of activities using a computerised use-of-time instrument, the Multimedia Activity Recall for Children and Adolescents (MARCA). Daily minutes of moderate-to-vigorous physical activity (MVPA) and screen time were calculated. The prevalence of compliance to Australian guidelines (> or = 60 min/day of MVPA and < or = 120 min/day of screen time outside of school hours) was calculated using the four methods. RESULTS: The four methods resulted in significantly different prevalence estimates for compliance to the MVPA guideline (20-68%), screen guideline (12-42%) and both guidelines (2-26%). Furthermore, different individuals were identified as compliant by the different methods. CONCLUSION: Clarification of how compliance to guidelines should be operationalised would assist in comparisons between studies, and in consistency in determining correlates of compliance.

The Multimedia Activity Recall for Children and Adolescents (MARCA): development and evaluation.

BACKGROUND: Self-report recall questionnaires are commonly used to measure physical activity, energy expenditure and time use in children and adolescents. However, self-report questionnaires show low to moderate validity, mainly due to inaccuracies in recalling activity in terms of duration and intensity. Aside from recall errors, inaccuracies in estimating energy expenditure from self-report questionnaires are compounded by a lack of data on the energy cost of everyday activities in children and adolescents. This article describes the development of the Multimedia Activity Recall for Children and Adolescents (MARCA), a computer-delivered use-of-time instrument designed to address both the limitations of self-report recall questionnaires in children, and the lack of energy cost data in children. METHODS: The test-retest reliability of the MARCA was assessed using a sample of 32 children (aged 11.8 +/- 0.7 y) who undertook the MARCA twice within 24-h. Criterion validity was assessed by comparing self-reports with accelerometer counts collected on a sample of 66 children (aged 11.6 +/- 0.8 y). Content and construct validity were assessed by establishing whether data collected using the MARCA on 1429 children (aged 11.9 +/- 0.8 y) exhibited relationships and trends in children's physical activity consistent with established findings from a number of previous research studies. RESULTS: Test-retest reliability was high with intra-class coefficients ranging from 0.88 to 0.94. The MARCA demonstrated criterion validity comparable to other self-report instruments with Spearman coefficients ranging from rho = 0.36 to 0.45, and provided evidence of good content and construct validity. CONCLUSION: The MARCA is a valid and reliable self-report questionnaire, capable of a wide variety of flexible use-of-time analyses related to both physical activity and sedentary behaviour, and offers advantages over existing pen-and-paper questionnaires.