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ObjectiveInvestigate whether resuming physical activity (PA) at 72 hours post concussion is safe and reduces symptoms at 2 weeks, compared with resting until asymptomatic.MethodsReal-life conditions, multicentre, single-blinded randomised clinical trial, conducted in three Canadian paediatric emergency departments (ED). Children/youth aged 10–Results456 randomised participants (EG: N=227; mean (SD) age=13.3 (2.1) years; 44.5% women; CG: N=229; mean (SD) age=13.3 (2.2) years; 43.7% women) were analysed. No AE were identified. ITT analysis showed no strong evidence of a group difference at 2 weeks (adjusted mean difference=−1.3 (95% CI:−3.6 to 1.1)). In adherent participants, initiating PA 72 hours post injury significantly reduced symptoms 2 weeks post injury, compared with rest (adjusted mean difference=−4.3 (95% CI:−8.4 to –0.2)).ConclusionSymptoms at 2 weeks did not differ significantly between children/youth randomised to initiate PA 72 hours post injury versus resting until asymptomatic; however, many were non-adherent to the intervention. Among adherent participants, early PA was associated with reduced symptoms at 2 weeks. Resumption of PA is safe and may be associated with milder symptoms at 2 weeks.Level of evidence1b.Trial registration numberNCT02893969.Registry namePediatric Concussion Assessment of Rest and Exertion (PedCARE).

Background Perfluoroalkyl substances can disrupt hepatic metabolism and may be associated with liver function biomarkers. We examined individual and mixture associations of PFAS on liver function biomarkers in a representative sample of Canadian adults. We explored the potential for effect modification by sex and body mass index, as well as by physical activity level which may attenuate the deleterious effect of PFAS on metabolic disorders. Methods We analyzed data from participants aged 20–74 from the Canadian Health Measures Survey. We used linear regression to examine associations between plasma concentrations of PFOA, PFOS, PFHxS, PFNA, PFDA, and PFUDA on serum concentrations of aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT) and total bilirubin. We used quantile g-computation to estimate associations with a PFAS mixture for each simultaneous, one-quartile change in PFAS concentrations. Results Each doubling of PFOA, PFOS, PFHxS, or PFNA concentrations was associated with higher AST, GGT, and ALP concentrations. Each doubling of PFOA concentrations was associated with 16.5% (95%CI: 10.4, 23.0) higher GGT concentrations among adults not meeting Canada’s physical activity guidelines vs. 6.6% (95%CI: -1.6, 15.5) among those meeting these guidelines. Sex and BMI also modified some associations, though to a lesser extent. We did not observe associations between ALT and PFOA (1.2% change; 95%CI: -2.5, 4.9), PFOS (2.2% change; 95%CI: -0.8, 5.3), or PFHxS (1.5% change; 95%CI: -0.4, 3.4). We also did not observe consistent associations for PFDA and PFUDA or with total bilirubin. In quantile g-computation models, each simultaneous one-quartile increase in the PFAS mixture was positively associated with AST (7.5% higher; 95%CI: 4.0, 10.4), GGT (9.7% higher; 95%CI: 1.7, 17.0), and ALP (2.8% higher; 95%CI: 0.5, 5.4). Conclusion Higher plasma concentrations of PFOA, PFOS, PFHxS, and PFNA – both individually and as a mixture – were associated with higher serum concentrations of liver function biomarkers. These results contribute to emerging evidence suggesting that higher levels of physical activity appear to be protective against the hepatotoxic effects of PFOA. This work contributes to a growing body of evidence supporting the hepatotoxic effects of PFAS.

National health and nutrition monitoring is an important federal effort in the United States and Canada, and the basis for many of their nutrition and health policies. Understanding of child exposures through human milk (HM) remains out of reach due to lack of current and representative data on HM's composition and intake volume. This article provides an overview of the current national health and nutrition monitoring activities for HM-fed children, HM composition (HMC) and volume data used for exposure assessment, categories of potential measures in HM, and associated variability factors. In this Perspective, we advocate for a framework for collection and reporting of HMC data for national health and nutrition monitoring and programmatic needs, including a shared vision for a publicly available Human Milk Composition Data Repository (HMCD-R) to include essential metadata associated with HMC. HMCD-R can provide a central, integrated platform for researchers and public health officials for compiling, evaluating, and sharing HMC data. The compiled compositional and metadata in HMCD-R would provide pertinent measures of central tendency and variability and allow use of modeling techniques to approximate compositional profiles for subgroups, providing more accurate exposure assessments for purposes of monitoring and surveillance. HMC and related metadata could facilitate understanding the complexity and variability of HM composition, provide crucial data for assessment of infant and maternal nutritional needs, and inform public health policies, food and nutrition programs, and clinical practice guidelines.

N,N-diethyl-m-toluamide (DEET) is an ingredient found in many consumer insect repellents and its use is recommended to Canadians by government agencies, including Health Canada, for protection against insect bites including mosquitos and ticks. The majority of research on DEET exposure and toxicokinetics in humans has focused on adult populations with little information from vulnerable populations, including children. We aimed to fill this knowledge gap by examining real-world exposure data for DEET and its metabolite 3-diethylcarbamoyl benzoic acid (DCBA) in a sample population of Canadian children. We conducted a 24-h observational exposure human biomonitoring study at three overnight summer camps in Ontario, Canada through July and August 2019. Participating children aged 7-13 years provided multiple spot urine samples over a 24-h period and completed a journal to document insect repellent use and factors that could influence absorption of DEET. Children were instructed to use insect repellent as they usually would while attending a summer camp. Exposure was quantified using the information from the participant's journal and the change in the mass of their insect repellent containers over the course of the study. A total of 389 urine samples were collected from 124 children. Among participants using insect repellent, urinary levels of DEET were elevated between 2 and 8 h post-application and decreased thereafter but remained qualitatively higher than concentrations in participants who did not use insect repellent on the study day, even at 18-22 h post-application. DCBA was the predominant metabolite of DEET exposure in urine. DCBA was elevated between 8 and 14 h post-application, and declined thereafter, but not to the level observed among those who did not use insect repellent on the study day. Children who used more insect repellent, or used higher concentration insect repellent (10%-30% DEET) excreted higher levels of DEET and DCBA. Excreted DEET and DCBA accounted for 0.001% (median) and 1.3% (median) of the estimated applied DEET, respectively. Children did not reach an undetectable level of DEET or DCBA in urine, even among those not using insect repellent during the study day, indicating a potentially complex multi-route exposure to insect repellents in a real world scenario. This work provides targeted biomonitoring data for children intentionally using DEET-based insect repellents for normal protective use, and will support the risk re-evaluation of DEET by Health Canada.

Glyphosate is the most widely applied herbicide in agriculture. Glufosinate is a broad spectrum herbicide used to manage glyphosate-resistant weeds. Despite the widespread use of these herbicides, biomonitoring data - which inform risk assessment and management - are sparse.To identify determinants of urinary concentrations of these herbicides and their metabolites in pregnancy.We measured urinary concentrations of glyphosate, glufosinate, and their primary metabolites aminomethylphosphonic acid (AMPA) and 3-methylphosphinicopropionic acid (3-MPPA) in a single spot urine specimen collected during the first trimester of pregnancy from the Maternal-Infant Research on Environmental Chemicals (MIREC) study. MIREC recruited about 2000 pregnant women from 10 Canadian cities between 2008 and 2011. We used UItra-Performance Liquid Chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) with sensitive limits of detection to quantify analyte concentrations. We examined urinary concentrations according to maternal sociodemographics, sample collection characteristics, reported pesticide use, and consumption of fruits, vegetables, legumes, and grain products. We used ANOVA models with specific gravity-standardized chemical concentrations as the dependent variable to determine associations with maternal and sample determinants.Among women with biobanked urine samples (n = 1829-1854), 74% and 72% had detectable concentrations of glyphosate and AMPA, respectively. In contrast, one and six percent of women had detectable concentrations of glufosinate and 3-MPPA, respectively. The specific gravity-standardized geometric mean (95% CI) concentrations of glyphosate and AMPA were 0.112 (0.099-0.127) μg/L and 0.159 (0.147-0.172) μg/L, respectively. We observed a dose-response relationship between consumption of whole grain bread and higher urinary glyphosate concentrations. Season of urine collection and self-reported pesticide use were not associated with increased concentrations of any analyte.We detected glyphosate and AMPA in the majority of pregnant women from this predominantly urban Canadian cohort. Diet was a probable route of exposure.

Relationships between PM

Biomonitoring data of N,N-diethyl-meta-toluamide (DEET) in children is scarce and limited to controlled exposure and surveillance studies. We conducted a 24-hour observational exposure and human biomonitoring study designed to estimate use of and exposure to DEET-based insect repellents by Canadian children in an overnight summer camp setting. Here, we present our study design and methodology. In 2019, children between the ages of 7 and 13 took part in the study (n = 126). Children controlled their use of DEET-based insect repellents, and provided an account of their activities at camp that could impact insect repellent absorption. Children provided a total of 389 urine samples throughout the study day, and reported the time that they applied insect repellent, which allowed us to contextualize urinary DEET and metabolite concentrations with respect to the timing of insect repellent application. DEET (2.3% N,N-diethyl-m-(hydroxymethyl)benzamide (DHMB) (0%

Highlights • Many movement behavior characteristics were associated with cardiometabolic risk. • Movement intensities were more consistently correlate with cardiometabolic risk. • Higher physical activity intensities were the strongest correlates of risk., Purpose The purpose of this study was to determine which intensities, patterns, and types of 24-h movement behaviors are most strongly associated with cardiometabolic risk factors among children. Methods A total of 369 children aged 10–13 years were studied. Participants wore an Actical accelerometer and a Garmin Forerunner 220 Global Positioning System logger and completed an activity and sleep log for 7 days. Data from these instruments were combined to estimate average minute per day spent in 14 intensities, 11 types, and 14 patterns of movement. Body mass index, resting heart rate, and systolic blood pressure values were combined to create a cardiometabolic risk factor score. Partial least squares regression analysis was used to examine associations between the 39 movement behavior characteristics and the cardiometabolic risk factor score. The variable importance in projection (VIP) values were used to determine and rank important movement behavior characteristics. There was evidence of interaction by biological maturity, and the analyses were conducted separately in the 50% least mature and 50% most mature participants. Results For the least biologically mature participants, fifteen of the 39 movement behavior characteristics had important VIP value scores; eight of these reflected movement intensities (particularly moderate and vigorous intensities), six reflected movement patterns, and one reflected a movement type. For the most mature participants, thirteen of the 39 movement behavior characteristics had important VIP value scores, with five reflecting intensities (particularly moderate and vigorous intensities), five reflecting patterns, and three reflecting types of movement. Conclusion More than 12 movement behavior characteristics were associated with cardiometabolic risk factors within both the most and least mature participants. Movement intensities within the moderate and vigorous intensity ranges were the most consistent correlates of these risk factors., Graphical abstract Image, graphical abstract

Supplemental Digital Content is available in the text., Background: Epidemiologic studies have consistently reported associations between air pollution and pregnancy outcomes including preeclampsia and gestational diabetes. However, the biologic mechanisms underlying these relationships remain unclear as few studies have collected relevant biomarker data. We examined relationships between ambient PM2.5 and NO2 with markers of inflammation during pregnancy in a prospective cohort of Canadian women. Methods: We analyzed data from 1170 women enrolled in the Maternal-Infant Research on Environmental Chemicals study. Daily residential PM2.5 and NO2 exposures during pregnancy were estimated using satellite-based and land-use regression models and used to create 14-day and 30-day exposure windows before blood-draw. Inflammatory markers C-reactive protein, interleukin-6, interleukin-8, and tumor necrosis factor-α were measured in third trimester plasma samples. Multivariable linear regression was used to estimate associations for an interquartile range (IQR) increase in PM2.5 and NO2 and markers of inflammation, while adjusting for individual-level confounders. Results: Fourteen-day (IQR: 6.85 µg/m3) and 30-day (IQR: 6.15 µg/m3) average PM2.5 exposures before blood-draw were positively associated with C-reactive protein after adjustment for covariates (24.6% [95% CI = 9.4, 41.9] and 17.4% [95% CI = 1.0, 35.0] increases, respectively). This association was found to be robust in several sensitivity analyses. Neither PM2.5 nor NO2 exposures were associated with interleukin-6, interleukin-8, or tumor necrosis factor-α. Conclusion: Exposure to ambient PM2.5 is positively associated with maternal inflammatory pathways in late pregnancy. This may contribute to positive associations between ambient PM2.5 and risk of adverse pregnancy outcomes.

Low 25-hydroxyvitamin D (25OHD), a biomarker of vitamin D status, is associated with reduced immune function and adverse pregnancy outcomes, such as preterm birth. Observational studies indicate that long-term, high level exposure to metals such as cadmium (Cd) and lead (Pb) can impact a person's vitamin D status. However, the directionality of the association is uncertain, particularly for low-level exposures. We used three distinct longitudinal data analysis methods to investigate cross-sectional, longitudinal and bidirectional relationships of Cd and Pb biomarkers with 25-hydroxyvitamin D (25OHD) in a Canadian pregnancy cohort. Maternal whole blood Cd and Pb and plasma 25OHD concentrations were measured in the 1st (n = 1905) and 3rd (n = 1649) trimester and at delivery (25OHD only, n = 1542). Our multivariable linear regression analysis showed weak inverse associations between Cd and 25OHD concentrations cross-sectionally and longitudinally while the latent growth curve models showed weak associations with Pb on the 25OHD intercept. In the bidirectional analysis, using cross lagged panel models, we found no association between 1st trimester metals and 3rd trimester 25OHD. Instead, 1st trimester 25OHD was associated with 9% (-15%, -3%) lower 3rd trimester Cd and 3% (-7, 0.1%) lower Pb. These findings suggest the 25OHD may modify metal concentrations in pregnancy and demonstrates the value of controlling for contemporaneous effects and the persistence of a biomarker over time, in order to rule out reverse causation.

This study examined the temporal relationship between objective measures of neighborhood crime and active transportation among children. A sample of 387 children aged 10–13 years from Kingston, Canada were studied between January 2015 and December 2016. Active transportation was measured over 7 days using Geographic Information System loggers. The number of crimes per capita were measured within a 1 km distance of participants' homes for the 24-month period prior to when their active transportation was measured. Surprisingly, children living in neighborhoods in the highest neighborhood crime rate quartile engaged in significantly more active transportation than children living in neighborhoods in the lowest neighborhood crime rate quartile (16.4 versus 10.2 min/day, p

Background A limitation of measuring sedentary time with an accelerometer is device removal. The resulting nonwear time is typically deleted from the data prior to calculating sedentary time. This could impact estimates of sedentary time and its associations with health indicators. We evaluated whether using multiple imputation to replace nonwear accelerometer epochs influences such estimates in children. Methods 452 children (50% male) aged 10–13 were tasked with wearing an accelerometer (15 s epochs) for 7 days. On average, 8% of waking time was classified as nonwear time. Sedentary time was derived from a “nonimputed” dataset using the typical approach of deleting epochs that occurred during nonwear time, as well as from an “imputed” dataset. In the imputed dataset, each nonwear epoch was re-classified as being as sedentary or not using multiple imputation (5 iterations) which was informed by the likelihood of a wear time epoch being classified as sedentary or not using parameter estimates from a logistic regression model. Estimates of sedentary time and associations between sedentary time and health indicators (cardiometabolic risk factor and internalizing mental health symptoms Z-scores) were compared between the nonimputed and imputed datasets. Results On average, sedentary time was 33 min/day higher in the imputed dataset than in the nonimputed dataset (632 vs. 599 min/day). The association between sedentary time and the cardiometabolic risk factor Z-score was stronger in the imputed vs. the nonimputed dataset (β = 0.137 vs. β = 0.092 per 60 min/day change, respectively). These findings were more pronounced among children who had

OBJECTIVES: To use a predominately objective measurement approach to assess and describe: (1) the amount of time that children aged 10–13 years spend participating in outdoor active play, active travel, curriculum-based physical activity at school, and organized sport; (2) the movement intensity composition of these four types of physical activity (i.e., % of time spent at a sedentary, light, or moderate-to-vigorous intensity); and (3) the proportion of each movement intensity obtained by participating in these four types of physical activity. METHODS: Three hundred seventy-seven children aged 10–13 years from Kingston, Canada, were studied. Children wore an accelerometer and GPS watch for 7 days and recorded the start and end times of the school day, recess periods, and organized sport sessions on a log. These data were used to estimate time spent in the four types of physical activity and the movement intensity composition of these activities. RESULTS: Time spent in outdoor active play (36 min/day) and organized sport (40 min/day) was higher than that for active travel (17 min/day) and curriculum-based physical activity (26 min/day). With the exception of organized sport, values were higher for boys than for girls. Older children accumulated less outdoor active play and more active travel than younger children. The greatest proportion of light- and moderate-to-vigorous-intensity movement was attributed to outdoor active play. CONCLUSION: We used a primarily objective measurement approach to assess and describe the amount of time children aged 10–13 participate in four types of physical activity. These descriptive findings could be used to identify target areas for physical activity interventions and policies. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.17269/s41997-018-0157-z) contains supplementary material, which is available to authorized users.

This cross-sectional study examined the independent and interactive associations between objective and perceived measures of neighborhood pedestrian traffic safety and outdoor active play. A total of 458 children aged 10–13 years from Kingston, Canada were studied in 2015–2016. Outdoor active play was measured over 7 days using data from activity logs, accelerometers, and Global Positioning System loggers. Geographic Information System data were collected within 1 km of participants' homes and used to create traffic volume, traffic calming, traffic speed, and pedestrian infrastructure indexes. Parents' perceptions of these pedestrian safety domains were obtained by questionnaire. Most of the pedestrian safety measures were not significantly associated with outdoor active play, and there were no interactions between the objective and perceived measures (p > 0.3). The significant relationships are listed here. Children whose parents perceived moderate or high traffic speeds in their neighborhood had outdoor active play values that were 0.35 (SE = 0.10, p = 0.021) and 0.20 (SE = 0.15, p = 0.048) SD units higher, respectively, then children whose parents perceived low traffic speed. By comparison to children from neighborhoods in the lowest tertile, children from the highest traffic volume tertile had higher outdoor active play levels (0.26, SE = 0.12, p = 0.029), while children from neighborhoods in the moderate traffic calming tertile (−0.28, SE = 0.11, p = 0.008) and the moderate pedestrian infrastructure tertile (−0.25, SE = 0.11, p = 0.023) had lower outdoor active play levels., Highlights • We determined if traffic safety was related to children's outdoor active play. • A cross-sectional study design was used. • Traffic safety was measured using subjectively and objectively. • Relationships between traffic safety and outdoor active play were inconsistent.

Current active transportation literature within children is based almost exclusively on questionnaire measures of the trip to school. This literature suggests that the walkability of the built environment can influence active transportation to school. The purpose of this study was to use objective measures to examine the relationship between neighborhood walkability and children's active transportation to school and other destinations. This was a cross-sectional study of 367 children and early adolescents (aged 10–13 years) from Kingston, Ontario, Canada. Participants wore a Garmin Forerunner 220 GPS watch during waking hours for seven consecutive days. Personal Activity Measurement Location System (PALMS) software used the GPS data to identify trips, and for each trip the time spent in that trip and the trip modality (active or passive). GIS measures of connectivity, proximity to destinations, and pedestrian infrastructure and safety were used to create a walkability index. Participants living in the neighborhoods with the highest walkability quartile spent an average of 16.2 min/day (95% CI: 11.8, 22.4) in active transportation while those in the lowest walkability quartile spent an average of 7.1 min/day (95% CI: 5.0, 10.4) in active transportation. Consistent patterns between walkability and active transportation were observed in age, sex, and season of study subgroups. An increase in active transportation minutes was seen across walkability quartiles for all of the most common active travel destinations (i.e., home, school, other people's homes). In conclusion, in this study of 10–13 year olds, those living in the most walkable neighborhoods accumulated more than twice as much active transportation than those living in the least walkable neighborhoods.

Background The purpose of this study was to investigate whether there is a bi-directional relationship between sleep characteristics (time in bed, sleep duration, sleep chronology, and sleep efficiency) and time spent participating in outdoor active play among children. Methods Participants consisted of 433 children aged 10–13 years from Kingston, ON, Canada. Time in bed, sleep duration, sleep chronology, and sleep efficiency were measured for 8 consecutive nights using data from a sleep log and Actical accelerometer. Outdoor active play was measured for the 7 days that fell in between these 8 nights using a combination of data from accelerometers, global positioning system loggers, and geographic information systems. Generalized estimating equation models were used to assess the relationships between sleep characteristics and outdoor active play. These models accounted for the repeated measures nested within participants and adjusted for several confounders (e.g., age, sex, family income, neighborhood traffic and green space). Results Time in bed, sleep duration, sleep chronology, and sleep efficiency were not significantly associated with the following day’s outdoor active play. There was a significant (p = 0.017) association between outdoor active play and the following night’s time in bed, which suggested that each hour increase in outdoor active play was associated with a 4.0 min increase in time in bed. Outdoor active play was not significantly associated with sleep duration, sleep chronology, or sleep efficiency. Conclusions None of the sleep characteristics predicted the following day’s outdoor active play. Increase time spent in outdoor active play predicted a longer time in bed, but not sleep duration, sleep chronology, or sleep efficiency.

Background: A limitation of accelerometer measures of moderate to vigorous physical activity (MVPA) is nonwear time. Nonwear-time data is typically deleted prior to estimating MVPA. In this study, we used an approach that used sociodemographic, health, and time data to guide the imputation of nonwear-time data. We determined whether imputing nonwear-time data influences estimates of MVPA and the association between MVPA, body mass index, and blood pressure. Methods: Seven days of accelerometer data were collected on 332 children aged 10–13 years. MVPA was estimated in a “nonimputed dataset,” wherein nonwear-time data were deleted prior to estimating MVPA, and in an “imputed dataset,” wherein nonwear-time data were imputed using sociodemographic and health characteristics of participants and time characteristics of the nonwear period prior to estimating MVPA. Results: Nonwear time represented 7% of waking hours. Average MVPA estimates did not differ in the nonimputed and imputed datasets (56.8 vs 58.4 min/d). The strength of the relationship between MVPA and the 2 health outcomes did not differ in the nonimputed and imputed datasets. Conclusions: Studies achieving high accelerometer wear-time compliance can obtain MVPA estimates without substantial bias if they use the traditional approach of deleting nonwear-time data.

Purpose The primary aim of this study was to develop an assessment of the fundamental, combined, and complex movement skills required to support childhood physical literacy. The secondary aim was to establish the feasibility, objectivity, and reliability evidence for the assessment. Methods An expert advisory group recommended a course format for the assessment that would require children to complete a series of dynamic movement skills. Criterion-referenced skill performance and completion time were the recommended forms of evaluation. Children, 8–12 years of age, self-reported their age and gender and then completed the study assessments while attending local schools or day camps. Face validity was previously established through a Delphi expert ( n = 19, 21% female) review process. Convergent validity was evaluated by age and gender associations with assessment performance. Inter- and intra-rater ( n = 53, 34% female) objectivity and test–retest ( n = 60, 47% female) reliability were assessed through repeated test administration. Results Median total score was 21 of 28 points (range 5–28). Median completion time was 17 s. Total scores were feasible for all 995 children who self-reported age and gender. Total score did not differ between inside and outside environments (95% confidence interval (CI) of difference: −0.7 to 0.6; p = 0.91) or with/without footwear (95%CI of difference: −2.5 to 1.9; p = 0.77). Older age ( p η 2 = 0.15) and male gender ( p η 2 = 0.02) were associated with a higher total score. Inter-rater objectivity evidence was excellent (intraclass correlation coefficient (ICC) = 0.99) for completion time and substantial for skill score (ICC = 0.69) for 104 attempts by 53 children (34% female). Intra-rater objectivity was moderate (ICC = 0.52) for skill score and excellent for completion time (ICC = 0.99). Reliability was excellent for completion time over a short (2–4 days; ICC = 0.84) or long (8–14 days; ICC = 0.82) interval. Skill score reliability was moderate (ICC = 0.46) over a short interval, and substantial (ICC = 0.74) over a long interval. Conclusion The Canadian Agility and Movement Skill Assessment is a feasible measure of selected fundamental, complex and combined movement skills, which are an important building block for childhood physical literacy. Moderate-to-excellent objectivity was demonstrated for children 8–12 years of age. Test–retest reliability has been established over an interval of at least 1 week. The time and skill scores can be accurately estimated by 1 trained examiner.

Background Perfluoroalkyl substances (PFAS) have been linked with a number of developmental, reproductive, hepatic, and cardiovascular health outcomes. However, the evidence for an association between PFAS and hypertensive disorders of pregnancy (including gestational hypertension and preeclampsia) is equivocal and warrants further investigation. Objectives To examine the relationship between background levels of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) and the development of gestational hypertension or preeclampsia in a Canadian pregnancy cohort. We also explored the potential for effect modification according to fetal sex. Methods Maternal plasma samples were collected in the first trimester from participants in the MIREC study and were analyzed for PFOA, PFOS, and PFHxS. Blood pressure was measured during each trimester. Gestational hypertension and preeclampsia were defined using the Society of Obstetricians and Gynaecologists of Canada guidelines. Logistic regression models were used to derive adjusted odds ratios (OR) and 95% confidence intervals (CI) for associations between PFAS concentrations (per doubling of concentration as well as according to tertiles) and gestational hypertension or preeclampsia. Linear mixed models were used to examine the association between PFAS concentrations and changes in blood pressure throughout pregnancy. Results Data from 1739 participants were analyzed. 90% of women were normotensive throughout pregnancy, 7% developed gestational hypertension without preeclampsia, and 3% developed preeclampsia. In the full analyses, neither PFOA nor PFOS were associated with gestational hypertension or preeclampsia. However, each doubling of PFHxS plasma concentration was associated with higher odds of developing preeclampsia (OR = 1.32; 95% CI: 1.03, 1.70). In addition, participants in the highest PFHxS tertile (1.4–40.0 μg/L) had higher odds of developing preeclampsia relative to those in the lowest tertile (OR = 3.06; 95% CI: 1.27, 7.39). In stratified analyses, this effect was only apparent among women carrying a female fetus (OR = 4.90; 95% CI: 1.02, 22.3). However, among women carrying a male fetus, both PFOS and PFHxS were associated with gestational hypertension, but not preeclampsia. Higher plasma concentrations of all three PFAS were associated with increases in diastolic blood pressure throughout pregnancy, and PFOA and PFHxS were also associated with systolic blood pressure. Discrepant findings were similarly revealed in analyses stratified by fetal sex. Conclusions Higher levels of PFHxS were associated with the development of preeclampsia, but not gestational hypertension. Neither PFOA nor PFOS were associated with either outcome. However, we show, for the first time, that fetal sex may modify these associations, a finding which warrants replication and further study.

Altering the proportion of total physical activity time accumulated while participating in different types of physical activity may influence health. Our objective was to use observational data to estimate whether replacing time from 1 type of physical activity with another is associated with physical and mental health indicators among children. Participants were 385 children aged 10–13 years. They wore a Global Positioning System watch and accelerometer and completed an activity log for 7 days. Data from these instruments was used to estimate time spent in outdoor active play, organized sport, curriculum-based physical activity at school, and active transportation. A cardiometabolic risk factor score was created from body fat, resting heart rate, and resting blood pressure measures. An internalizing symptoms score was created using anxiety and depression symptom questionnaire items. Isotemporal substitution models estimated if health indicators changed when time in 1 type of physical activity was replaced with equivalent time from another. The results indicated that time spent in all types of physical activity combined was associated with the cardiometabolic risk factor and internalizing symptom scores. Replacing active transportation with outdoor active play was associated with an increase in the internalizing symptoms score but a decrease in the cardiometabolic risk factor score. The internalizing symptoms score decreased when active transportation was replaced by equivalent time in organized sport. Other time substitutions were not significant. In conclusion, the total time spent participating in physical activity and not a specific type of physical activity was the most consistent correlate of the health indicators.

Background Children participate in four main types of physical activity: organized sport, active travel, outdoor active play, and curriculum-based physical activity. The objective of this study was to develop a valid approach that can be used to concurrently measure time spent in each of these types of physical activity. Methods Two samples (sample 1: n = 50; sample 2: n = 83) of children aged 10–13 wore an accelerometer and a GPS watch continuously over 7 days. They also completed a log where they recorded the start and end times of organized sport sessions. Sample 1 also completed an outdoor time log where they recorded the times they went outdoors and a description of the outdoor activity. Sample 2 also completed a curriculum log where they recorded times they participated in physical activity (e.g., physical education) during class time. Results We describe the development of a measurement approach that can be used to concurrently assess the time children spend participating in specific types of physical activity. The approach uses a combination of data from accelerometers, GPS, and activity logs and relies on merging and then processing these data using several manual (e.g., data checks and cleaning) and automated (e.g., algorithms) procedures. In the new measurement approach time spent in organized sport is estimated using the activity log. Time spent in active travel is estimated using an existing algorithm that uses GPS data. Time spent in outdoor active play is estimated using an algorithm (with a sensitivity and specificity of 85%) that was developed using data collected in sample 1 and which uses all of the data sources. Time spent in curriculum-based physical activity is estimated using an algorithm (with a sensitivity of 78% and specificity of 92%) that was developed using data collected in sample 2 and which uses accelerometer data collected during class time. There was evidence of excellent intra- and inter-rater reliability of the estimates for all of these types of physical activity when the manual steps were duplicated. Conclusions This novel measurement approach can be used to estimate the time that children participate in different types of physical activity. Electronic supplementary material The online version of this article (10.1186/s12889-018-5268-1) contains supplementary material, which is available to authorized users.

Television (TV) viewing is a risk factor for obesity in children. This is partly due to its promotion of energy intake by distracting from normal satiety signals. Children are exposed to a variety of TV programs which differ in features such as pacing. This is reason to believe that different children's TV shows distract to varying degrees, and can therefore influence energy intake to different extents. We suggest that future research should examine how different TV shows influence energy intake in children. Such research could help identify new ways to protect children from the negative effects of TV viewing on caloric intake and ultimately body weight.

The relationships among sedentary time, television viewing time, and dietary patterns in children are not fully understood. The aim of this paper was to determine which of self-reported television viewing time or objectively measured sedentary time is a better correlate of the frequency of consumption of healthy and unhealthy foods. A cross-sectional study was conducted of 9- to 11-year-old children (n = 523; 57.1% female) from Ottawa, Ontario, Canada. Accelerometers were used to determine total sedentary time, and questionnaires were used to determine the number of hours of television watching and the frequency of consumption of foods per week. Television viewing was negatively associated with the frequency of consumption of fruits, vegetables, and green vegetables, and positively associated with the frequency of consumption of sweets, soft drinks, diet soft drinks, pastries, potato chips, French fries, fruit juices, ice cream, fried foods, and fast food. Except for diet soft drinks and fruit juices, these associations were independent of covariates, including sedentary time. Total sedentary time was negatively associated with the frequency of consumption of sports drinks, independent of covariates, including television viewing. In combined sedentary time and television viewing analyses, children watching >2 h of television per day consumed several unhealthy food items more frequently than did children watching ≤2 h of television, regardless of sedentary time. In conclusion, this paper provides evidence to suggest that television viewing time is more strongly associated with unhealthy dietary patterns than is total sedentary time. Future research should focus on reducing television viewing time, as a means of improving dietary patterns and potentially reducing childhood obesity.

OBJECTIVE: To examine whether the number and type of electronic screens available in children’s bedrooms matter in their relationship to adiposity, physical activity and sleep. METHODS: A cross-sectional study was conducted involving 502 children aged 9-11 years from Ottawa, Ontario. The presence (yes/no) of a television (TV), computer or video game system in the child’s bedroom was reported by the parents. Percentage body fat was measured using bioelectrical impedance. An accelerometer was worn over seven days to assess moderate-to-vigorous physical activity (MVPA), total sedentary time, sleep duration and sleep efficiency. Screen time was self-reported by the child. RESULTS: After adjustment for age, sex, ethnicity, annual household income and highest level of parental education, children with 2-3 screens in their bedroom had a significantly higher percentage of body fat than children with no screen in their bedroom. However, while children with 2-3 screens in their bedroom engaged in more screen time overall than those with no screen, total sedentary time and MVPA were not significantly different. Sleep duration was not related to the number of screens in the bedroom, but sleep efficiency was significantly lower in children with at least 2 screens in the bedroom. Finally, children having only a TV in their bedroom had significantly higher adiposity than those having no screen at all. In contrast, the presence of a computer in children’s bedrooms was not associated with higher adiposity than that of children with no screen. CONCLUSIONS: A higher number of screens in a child’s bedroom was associated with higher adiposity, more total screen time and lower sleep efficiency. Having a TV in the bedroom appears to be the type of screen presence associated with higher levels of adiposity. Given the popularity of screens among children, these findings are increasingly relevant to health promotion strategies.

Background— International guidelines recommend restriction of activities for many children and adolescents with inherited arrhythmia syndromes to moderate activity ( Methods and Results— Participants wore the Actiheart for ≤7 days on 2 occasions after a maximal exercise test that was used to calibrate the monitor individually against intensity levels. Of 16 participants, 13 (81%) had long QT syndrome, 9 (56%) were female, and median age was 12 years. Monitors were worn for a median (range) of 13 (6–14) days, and a mean (SD) of 11.3 (1.7) hours per day. Vigorous (7 MET) and very vigorous (10 MET) thresholds were exceeded by 15 and 13 participants, respectively. The median (interquartile range), individual, total weekly time spent >7 MET threshold was 113 (65–330) minutes, whereas such time spent >10 MET threshold was 53 (9–115) minutes. Total time >7 MET threshold was 2.3% of monitor wear time. There were no differences in time above threshold between male and female participants ( P =0.357) or among those with different levels of activity restriction ( P =0.769). Conclusions— Current recommended activity guidelines are frequently exceeded during routine free-living activities in young participants with inherited arrhythmia syndromes. Whether this indicates increased risk for these individuals or excessively restrictive guidelines remains to be determined.

This project examined the feasibility, validity, and reliability of the plank isometric hold for children 8–12 years of age. 1502 children (52.5% female) performed partial curl-up and/or plank protocols to assess plank feasibility (n = 823, 52.1% girls), validity (n = 641, 54.1% girls) and reliability (n = 111, 47.8% girls). 12% (n = 52/431) of children could not perform a partial curl-up, but virtually all children (n = 1066/1084) could attain a nonzero score for the plank. Plank performance without time limit was influenced by small effects with age (β = 6.86; p < .001, η2 = 0.03), flexibility (β = 0.79; p < .001, η2 = 0.03), and medium effects with cardiovascular endurance (β = 1.07; p < .001, η2 = 0.08), and waist circumference (β = −0.92; p < .001, η2 = 0.06). Interrater (ICC = 0.62; CI = 0.50, 0.75), intrarater (ICC = 0.83; CI = 0.73, 0.90) and test-retest (ICC = 0.63; CI = 0.46, 0.75) reliability were acceptable for the plank without time limit. These data suggest the plank without time limit is a feasible, valid and reliable assessment of torso muscular endurance for children 8–12 years of age.

Moderate-to-vigorous physical activity (MVPA) is essential for disease prevention and health promotion. Emerging evidence suggests other intensities of physical activity (PA), including light-intensity activity (LPA), may also be important, but there has been no rigorous evaluation of the evidence. The purpose of this systematic review was to examine the relationships between objectively measured PA (total and all intensities) and health indicators in school-aged children and youth. Online databases were searched for peer-reviewed studies that met the a priori inclusion criteria: population (apparently healthy, aged 5–17 years), intervention/exposure/comparator (volumes, durations, frequencies, intensities, and patterns of objectively measured PA), and outcome (body composition, cardiometabolic biomarkers, physical fitness, behavioural conduct/pro-social behaviour, cognition/academic achievement, quality of life/well-being, harms, bone health, motor skill development, psychological distress, self-esteem). Heterogeneity among studies precluded meta-analyses; narrative synthesis was conducted. A total of 162 studies were included (204 171 participants from 31 countries). Overall, total PA was favourably associated with physical, psychological/social, and cognitive health indicators. Relationships were more consistent and robust for higher (e.g., MVPA) versus lower (e.g., LPA) intensity PA. All patterns of activity (sporadic, bouts, continuous) provided benefit. LPA was favourably associated with cardiometabolic biomarkers; data were scarce for other outcomes. These findings continue to support the importance of at least 60 min/day of MVPA for disease prevention and health promotion in children and youth, but also highlight the potential benefits of LPA and total PA. All intensities of PA should be considered in future work aimed at better elucidating the health benefits of PA in children and youth.

Accelerometry is the gold standard for field-based physical activity assessment in children; however, the plethora of devices, data reduction procedures, and cut-points available limits comparability between studies. This study aimed to compare physical activity variables from the ActiGraph GT3X+ and Actical accelerometers in children under free-living conditions. A cross-sectional study of 379 children aged 9-11 years from Ottawa (Canada) was conducted. Children wore the ActiGraph GT3X+ and Actical accelerometers on the hip simultaneously for 7 consecutive days (24-h protocol). Moderate-to-vigorous (MVPA), vigorous (VPA), moderate (MPA), and light (LPA) physical activity, as well as sedentary time, (SED) were derived using established data reduction protocols. Excellent agreement between devices was observed for MVPA (ICC = 0.73-0.80), with fair to good agreement for MPA, LPA and SED, and poor agreement for VPA. Bland-Altman plots showed excellent agreement for MVPA, LPA, and SED, adequate agreement for MPA, and poor agreement for VPA. MVPA derived from the Actical was 11.7% lower than the ActiGraph GT3X+. The ActiGraph GT3X+ and Actical are comparable for measuring children's MVPA. However, comparison between devices for VPA, MPA, LPA, and SED are highly dependent on data reduction procedures and cut-points, and should be interpreted with caution.

Adolescents spend up to 6–8 h/day in sedentary screen behaviour and screen time is an independent risk factor for obesity. However, the mechanisms by which screen time confers obesity risk remain unclear. Via community level recruitment this study examined whether the relationship between screen time behaviours and body mass index (BMI: kg/m2) was mediated by total energy intake or macronutrient consumption. In a cross-sectional study of post-pubertal adolescents (N = 283: 86M, 197F) with overweight or obesity at baseline of an intervention for weight control, we examined self-reported total energy intake (mean Calories from 3 day food diary), macronutrient intake (grams/day of carbohydrate, fat, protein) and total screen time (aggregate of hours/day watching TV, playing seated video games, and recreational computer use). BMI was objectively measured and converted to standardized scores (z-BMI). Simple and multiple mediation analyses were conducted using the bootstrapping approach described by Preacher and Hayes. Covariates included age, sex, ethnicity, parental education, Tanner stage, and self-reported physical activity. The relationship between screen time and z-BMI was significantly mediated by energy intake. Higher levels of carbohydrate intake, but not fat or protein intake, significantly mediated the relationship between screen time and z-BMI (95% bias-corrected and accelerated confidence interval [0.0004, 0.0074]). Higher carbohydrate intake mediated the relationship between TV viewing and z-BMI, and video gaming and z-BMI. In conclusion, the relationship between screen time and BMI appears to be mediated by increased energy intake, primarily in the form of higher carbohydrate intake. It is possible that reducing time spent watching TV and playing video games may reduce food intake and help promote dietary adherence needed for weight management in obese adolescents. Clinical Trial Registration ClinicalTrials.gov ID: NCT00195858 .

It is unclear if children of different weight status differ in their nutritional habits while watching television. The objective of the present paper was to determine if children who are overweight or obese differ in their frequency of consumption of six food items while watching television compared with their normal-weight counterparts. A cross-sectional study of 550 children (57·1 % female; mean age = 10 years) from Ottawa, Canada was conducted. Children's weight status was categorised using the Centers for Disease Control and Prevention cut-points. Questionnaires were used to determine the number of hours of television watching per day and the frequency of consumption of six types of foods while watching television. Overweight/obese children watched more television per day than normal-weight children (3·3v.2·7 h, respectively;P= 0·001). Obese children consumed fast food and fruits/vegetables more frequently while watching television than normal-weight or overweight children (PP= 0·03) of being obese, independent of several covariates, but not independent of moderate-to-vigorous physical activity. The finding that both television watching and the frequency of consumption of some food items during television watching are higher in children who are obese is concerning. While the nature of the present study does not allow for the determination of causal pathways, future research should investigate these weight-status differences to identify potential areas of intervention.

Summary Sleep disturbance is common among shift workers, and may be an important factor in the effect of shift work on chronic disease development. In this cross-sectional study, we described sleep patterns of 294 female hospital workers (142 alternating day–night shift workers, 152 day workers) and determined associations between shift work and sleep duration. Rest–activity cycles were recorded with the ActiGraph GT3X+ for 1 week. Analyses were stratified by chronotype of shift workers. Using all study days to calculate average sleep duration, shift workers slept approximately 13 min less than day workers during main sleep periods, while 24-h sleep duration did not differ between day workers and shift workers. Results from age-adjusted models demonstrated that all shift workers, regardless of chronotype, slept 20–30 min less than day workers on day shifts during main and total sleep. Early and intermediate chronotypes working night shifts slept between 114 and 125 min less than day workers, both with regard to the main sleep episode and 24-h sleep duration, while the difference was less pronounced among late chronotypes. When sleep duration on free days was compared between shift workers and day workers, only shift workers with late chronotypes slept less, by approximately 50 min, than day workers during main sleep. Results from this study demonstrate how an alternating day–night shift work schedule impacts sleep negatively among female hospital workers, and the importance of considering chronotype in sleep research among shift workers.

Background Demographic, family, and home characteristics play an important role in determining childhood sedentary behaviour. The objective of this paper was to identify correlates of total sedentary time (SED) and correlates of self-reported screen time (ST) in Canadian children. Methods Child- and parent-reported household, socio-demographic, behavioural, and diet related data were collected; directly measured anthropometric and accelerometer data were also collected for each child. Participants with complete demographic, anthropometric, and either SED (n=524, 41% boys) or ST (n=567, 42% boys) data from the Canadian site of the International Study of Childhood Obesity Lifestyle and the Environment (ISCOLE) were included in analysis. Sixteen potential correlates of SED and ST were examined using multilevel general linear models, adjusting for sex, ethnicity, number of siblings, and socio-economic status. All explanatory variables moderately associated (p

Cross-sectional associations between objectively-measured sleep duration, sleep efficiency and sleep timing with adiposity and physical activity were examined in a cohort of 567 children from Ottawa, Canada. Five-hundred and fifteen children (58.8% female; age: 10.0 ± 0.4 years) had valid sleep measurements and were included in the present analyses. Physical activity, sedentary time and sleep parameters were assessed over 7 days (actigraphy). Height, weight and waist circumference were measured according to standardized procedures. Percentage body fat was assessed using bioelectric impedance analysis. Light physical activity and sedentary time were greater in children with the shortest sleep durations (P < 0.0001), whereas children with the highest sleep efficiencies had lower light physical activity and more sedentary time across tertiles (P < 0.0001). In multivariable linear regression analyses, and after adjusting for a number of covariates, sleep efficiency was inversely related to all adiposity indices (P < 0.05). However, sleep duration and sleep timing were not associated with adiposity indices after controlling for covariates. Inverse associations were noted between sleep duration and light physical activity and sedentary time (P < 0.0001). Sleep efficiency (P < 0.0001), wake time and sleep timing midpoint (P < 0.05) were negatively associated with light physical activity, but positively associated with sedentary time. In conclusion, only sleep efficiency was independently correlated with adiposity in this sample of children. Participants with the shortest sleep durations or highest sleep efficiencies had greater sedentary time. More research is needed to develop better sleep recommendations in children that are based on objective measures of sleep duration, sleep efficiency and sleep timing alike.

Purpose: To gather the perspectives of physiotherapists and physiotherapist assistants on essential competencies for intraprofessional (physiotherapist–physiotherapist assistant) collaboration. Method: A survey was developed to gather physiotherapist and physiotherapist assistant perceptions of the essential elements of effective and efficient intraprofessional collaborative practice. Participants were asked to rate the importance of 36 elements in 6 different categories (communication, collaboration, consultation, assignment of tasks, conflict management, and roles/responsibilities) involved in intraprofessional practice. Results: A total of 1049 physiotherapists and 121 physiotherapist assistants responded to the survey. Analysis identified 10 competency elements perceived by participants as essential to effective and efficient intraprofessional collaboration. Comparisons using demographic variables consistently yielded the same top 10 elements. Conclusions: Our results indicated that physiotherapists and physiotherapist assistants working in private and public practice share very similar views on what is essential for effective intraprofessional practice. The consensus is that communication is key; open lines of communication help to determine responsibilities. Physiotherapy pre-licensure and continuing education programmes should include opportunities to work on communication, listening, and the skills needed to interact and collaborate effectively.

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).