Publications

Background: Actical accelerometer thresholds have been derived to enable objective measurement of time spent performing sedentary activity in children and adolescents, but not adults. Thus, the purpose of this study was to determine Actical accelerometer sedentary activity thresholds for adults. Methods: Data were available from 3187 participants aged 6 to 79 years from a preliminary partial dataset of the Canadian Health Measures Survey, who wore an Actical for 7 days. Step count data were used to evaluate the use of 50, 100, and 800 counts per min (cpm) as sedentary activity thresholds. Minutes when no steps were recorded were considered minutes of sedentary activity. Results: The use of higher cpm thresholds resulted in a greater percentage of sedentary minutes being correctly classified as sedentary. The percentage of minutes that were incorrectly classified as sedentary was substantially higher when using a threshold of 800 cpm compared with 50 or 100 cpm. Results were similar for children, adolescents, and adults. Conclusions: These findings suggest that a threshold of 100 cpm is appropriate for classifying sedentary activity of adults when using the Actical. As such, wear periods with minutes registering less than 100 cpm would be classified as time spent performing sedentary activity.

BACKGROUND Maternal obesity, low birthweight, and accelerated growth have been shown to be associated with elevated blood pressure in children. However, it is unknown which growth periods are associated with blood pressure, and whether birthweight or maternal obesity modify the relationship between growth and blood pressure in early childhood. OBJECTIVES We examined the relationship between age- and sex-standardized body mass index (zBMI) growth trajectories with longitudinal measures of systolic (SBP) and diastolic (DBP) blood pressure in early childhood. DESIGN/METHODS We collected repeated measures of zBMI and blood pressure in 2502 children participating in the TARGet Kids! cohort. In stage 1 we used linear spline multilevel models to estimate each child’s zBMI at birth and zBMI growth trajectories in early infancy (0–3 m), late infancy (3–18 m) and toddler years (18–36 m). In stage 2 we used generalized estimating equations to examine the relationship between zBMI at birth and zBMI growth with repeated measures of SBP and DBP from 3 to 6 years of age. We tested for effect modification by birthweight and maternal obesity status by inclusion of interaction terms in each growth period. RESULTS After adjusting for confounders and prior growth, a 1 standard deviation unit increase in zBMI growth per month in early infancy (β=0.59; 95% CI 0.32,0.87) and late infancy (β=0.73; 95% CI 0.44,1.01), were associated with higher SBP. Growth in the toddler years was not significantly associated with SBP (p=0.08). Similar but smaller associations were observed for zBMI growth and DBP in early (β=0.29; 95% CI 0.04, 0.53) and late infancy (β=0.42; 95% CI 0.18, 0.66). Birthweight status modified (p=0.004) the relationship between zBMI growth and SBP during late infancy, with the strongest positive association observed in the low birthweight group. During toddler years, birthweight status modified the relationship between zBMI growth with SBP (p=0.03) and DBP (p=0.04), with the strongest positive association observed in the low birthweight group, followed by the high birthweight group. Maternal obesity status modified (p= 0.03) the relationship between zBMI growth with DBP in late infancy, with a stronger association observed among children of mothers with obesity. CONCLUSION Accelerated growth in early and late infancy are associated with increased blood pressure in early childhood. Growth during late infancy and toddler years may impact blood pressure differently in children born with high and low birthweights and high maternal BMI, suggesting prospective windows and risk groups to target interventions.

Purpose There is a paucity of global data on sedentary behavior during early childhood. The purpose of this study was to examine how device-measured sedentary behavior in young children differed across geographically, economically, and sociodemographically diverse populations, in an international sample. Methods This multinational, cross-sectional study included data from 1071 children 3–5 yr old from 19 countries, collected between 2018 and 2020 (pre-COVID). Sedentary behavior was measured for three consecutive days using activPAL accelerometers. Sedentary time, sedentary fragmentation, and seated transport duration were calculated. Linear mixed models were used to examine the differences in sedentary behavior variables between sex, country-level income groups, urban/rural settings, and population density. Results Children spent 56% (7.4 h) of their waking time sedentary. The longest average bout duration was 81.1 ± 45.4 min, and an average of 61.1 ± 50.1 min·d −1 was spent in seated transport. Children from upper-middle–income and high-income countries spent a greater proportion of the day sedentary, accrued more sedentary bouts, had shorter breaks between sedentary bouts, and spent significantly more time in seated transport, compared with children from low-income and lower-middle–income countries. Sex and urban/rural residential setting were not associated with any outcomes. Higher population density was associated with several higher sedentary behavior measures. Conclusions These data advance our understanding of young children’s sedentary behavior patterns globally. Country income levels and population density appear to be stronger drivers of the observed differences, than sex or rural/urban residential setting.

Research is now required on factors influencing adults' sedentary behaviors, and effective approaches to behavioral-change intervention must be identified. The strategies for influencing sedentary behavior will need to be informed by evidence on the most important modifiable behavioral determinants. However, much of the available evidence relevant to understanding the determinants of sedentary behaviors is from cross-sectional studies, which are limited in that they identify only behavioral “correlates.” As is the case for physical activity, a behavior- and context-specific approach is needed to understand the multiple determinants operating in the different settings within which these behaviors are most prevalent. To this end, an ecologic model of sedentary behaviors is described, highlighting the behavior settings construct. The behaviors and contexts of primary concern are TV viewing and other screen-focused behaviors in domestic environments, prolonged sitting in the workplace, and time spent sitting in automobiles. Research is needed to clarify the multiple levels of determinants of prolonged sitting time, which are likely to operate in distinct ways in these different contexts. Controlled trials on the feasibility and efficacy of interventions to reduce and break up sedentary behaviors among adults in domestic, workplace, and transportation environments are particularly required. It would be informative for the field to have evidence on the outcomes of “natural experiments,” such as the introduction of nonseated working options in occupational environments or new transportation infrastructure in communities.

Objective The American Academy of Pediatrics recommends developmental surveillance and screening in early childhood in primary care. The 18-month visit may be an ideal time for identification of children with delays in language and communication, or symptoms of autism spectrum disorder (ASD). Little is known about the predictive validity of developmental screening tools administered at 18 months. Our objective was to examine the predictive validity of the Infant Toddler Checklist (ITC) at the 18-month health supervision visit, using school readiness at kindergarten age as the criterion measure. Methods We designed a prospective cohort study, recruiting in primary care in Toronto, Canada. Parents completed the ITC at the 18-month visit. Teachers completed the Early Development Instrument (EDI) when the children were in Kindergarten, age 4–6 years. We calculated screening test properties with 95% confidence intervals (CIs). We used multivariable logistic and linear regression analyses adjusted for important covariates. Results Of 293 children (mean age 18 months), 30 (10.2%) had a positive ITC including: concern for speech delay (n = 11, 3.8%), concern for other communication delay (n = 13, 4.4%), and concern for both (n = 6, 2.0%). At follow-up (mean age 5 years), 54 (18.4%) had overall EDI vulnerability, 19 (6.5%) had vulnerability on the 2 EDI communication domains. The ITC sensitivity ranged from 11% to 32%, specificity from 91% to 96%, false positive rates from 4% to 9%, PPV from 16% to 35%, NPV from 83% to 95%. A positive ITC screen and ITC concern for speech delay were associated with lower scores in EDI communication skills and general knowledge (β = −1.08; 95% CI: −2.10, −0.17; β = −2.35; 95% CI: −3.63, −1.32) and EDI language and cognitive development (β = −0.62; 95% CI: −1.25, −0.18; β = −1.22; 95% CI: −2.11, −0.58). Conclusions The ITC demonstrated high specificity suggesting that most children with a negative ITC screen will demonstrate school readiness at 4–6 years, and low false positive rates, minimizing over-diagnosis. The ITC had low sensitivity highlighting the importance of ongoing developmental surveillance and screening.

Background Existing sedentary behaviour guidelines for children and youth target overall sedentary behaviour and recreational screen time, without any specific recommendations regarding school-related sedentary behaviours (i.e., sedentary behaviours performed during the school day, or within the influence of school). The purpose of this paper is to describe the development of international evidence-based recommendations for school-related sedentary behaviours for children and youth, led by the Sedentary Behaviour Research Network (SBRN). Methods A panel of international experts was convened by SBRN in November 2020 to guide the development of these recommendations for children and youth aged ~ 5–18 years. The recommendations were informed by 1) age-relevant existing sedentary behaviour guidelines, 2) published research on the relationship between overall sedentary behaviour and health, 3) a de novo systematic review on the relationship between school-related sedentary behaviours and health and/or academic outcomes, and 4) a de novo environmental scan of the grey literature to identify existing recommendations for school-related sedentary behaviours. Draft recommendations were presented to the Expert Panel in June 2021. Following thorough discussion and modifications, updated recommendations were distributed for stakeholder feedback from July 9–26. Feedback was received from 148 stakeholders across 23 countries, leading to additional updates to the recommendations. Following further rounds of discussion and updates with the Expert Panel in August and September 2021, consensus was achieved on the final recommendations. Results A healthy day includes breaking up extended periods of sedentary behaviour and incorporating different types of movement into homework whenever possible, while limiting sedentary homework. School-related screen time should be meaningful, mentally or physically active, and serve a specific pedagogical purpose that enhances learning. Replacing sedentary learning activities with movement-based learning activities, and replacing screen-based learning activities with non-screen-based learning activities, can further support students’ health and wellbeing. Discussion This paper presents the first evidence-based recommendations for school-related sedentary behaviours for children and youth. These recommendations will support the work of parents, caregivers, educators, school system administrators, policy makers, researchers and healthcare providers interested in promoting student health and academic success.

Accurate assessment is required to assess current and changing physical activity levels, and to evaluate the effectiveness of interventions designed to increase activity levels. This study systematically reviewed the literature to determine the extent of agreement between subjectively (self-report e.g. questionnaire, diary) and objectively (directly measured; e.g. accelerometry, doubly labeled water) assessed physical activity in adults.Eight electronic databases were searched to identify observational and experimental studies of adult populations. Searching identified 4,463 potential articles. Initial screening found that 293 examined the relationship between self-reported and directly measured physical activity and met the eligibility criteria. Data abstraction was completed for 187 articles, which described comparable data and/or comparisons, while 76 articles lacked comparable data or comparisons, and a further 30 did not meet the review's eligibility requirements. A risk of bias assessment was conducted for all articles from which data was abstracted.Correlations between self-report and direct measures were generally low-to-moderate and ranged from -0.71 to 0.96. No clear pattern emerged for the mean differences between self-report and direct measures of physical activity. Trends differed by measure of physical activity employed, level of physical activity measured, and the gender of participants. Results of the risk of bias assessment indicated that 38% of the studies had lower quality scores.The findings suggest that the measurement method may have a significant impact on the observed levels of physical activity. Self-report measures of physical activity were both higher and lower than directly measured levels of physical activity, which poses a problem for both reliance on self-report measures and for attempts to correct for self-report - direct measure differences. This review reveals the need for valid, accurate and reliable measures of physical activity in evaluating current and changing physical activity levels, physical activity interventions, and the relationships between physical activity and health outcomes.

No abstract is provided for this article.

No abstract is provided for this article.

The purpose of this study was to examine the validity of the SC-StepMX pedometer for measuring step counts. A convenience sample of 40 participants wore 4 SC-StepMX pedometers, 2 Yamax DigiWalker pedometers, and 2 Actical accelerometers around their waist on a treadmill at 4 speeds based on each participant's self-paced walking speed (50%, 100%, 180%, and 250%; range: 1.4-14.1 km·h(-1)). The SC-StepMX demonstrated lower mean absolute percent error (-0.2%) compared with the Yamax DigiWalker (-20.5%) and the Actical (-26.1%). Mean measurement bias was lower for the SC-StepMX (0.1 ± 9.1; 95% confidence interval = -17.8 to 18.0 steps·min(-1)) when compared with both the Yamax DigiWalker (-15.9 ± 23.3; 95% confidence interval = -61.6 to 29.7 steps·min(-1)) and the Actical (-22.0 ± 36.3; 95% CI = -93.1 to 49.1 steps·min(-1)). This study demonstrates that the SC-StepMX pedometer is a valid tool for the measurement of step counts. The SC-StepMX accurately measures step counts at slower walking speeds when compared with 2 other commercially available activity monitors. This makes the SC-StepMX useful in measuring step counts in populations that are active at lower intensities (e.g., sedentary individuals, the elderly).