Mean Weekday Research Articles

Accelerometer-measured physical activity and sedentary time among children and their parents in the UK before and after COVID-19 lockdowns: a natural experiment

Abstract Background Restrictions due to the coronavirus disease 2019 (COVID-19) pandemic reduced physical activity provision for both children and their parents. Recent studies have reported decreases in physical activity levels during lockdown restrictions, but these were largely reliant on self-report methods, with data collected via unrepresentative self-report surveys. The post-pandemic impacts on children’s activity levels remain unknown. A key question is how active children become once lockdown restrictions are lifted. Methods Active-6 is a repeated cross-sectional natural experiment. Accelerometer data from 1296 children aged 10–11 and their parents were collected in 50 schools in the Greater Bristol area, UK in March 2017-May 2018 (pre-COVID-19 comparator group), and compared to 393 children aged 10–11 and parents in 23 of the same schools, collected in May-December 2021. Mean minutes of accelerometer-measured moderate-to-vigorous physical activity (MVPA) were derived for weekdays and weekend and compared pre- and post-lockdown via linear multilevel models. Results After adjusting for seasonality, accelerometer wear time and child/parent demographics, children’s mean weekday and weekend MVPA were 7.7 min (95% CI: 3.5 to 11.9) and 6.9 min (95% CI: 0.9 to 12.9) lower in 2021 than in 2018, respectively, while sedentary time was higher by 25.4 min (95% CI: 15.8 to 35.0) and 14.0 min (95% CI: 1.5 to 26.5). There was no evidence that differences varied by child gender or household education. There was no significant difference in parents’ MVPA or sedentary time, either on weekdays or weekends. Conclusions Children’s MVPA was lower by 7–8 min/day in 2021 once restrictions were lifted than before the pandemic for all groups, on both weekdays and weekends. Previous research has shown that there is an undesirable age-related decline in children’s physical activity. The 8-min difference reported here would be broadly comparable to the decline that would have previously been expected to occur over a three-year period. Parents’ physical activity was similar to pre-pandemic levels. Our results suggest that despite easing of restrictions, children’s activity levels have not returned to pre-pandemic levels. There is an urgent need to understand why these changes have occurred and how long they are maintained.

Initial observations on the impact of implementation of a seven-day clinical pharmacy service on dispensary activity and performance

Abstract Introduction The need for seven-day clinical pharmacy services is widely acknowledged, although limited, in the acute sector of the National Health Service.1,2 Timely medicine supply is integral to provision of improved clinical pharmacy services to patients across seven-days, and is essential in effective discharge planning. There is a paucity of evidence for implementation of seven-day clinical pharmacy services, including the impact of service transformation on dispensary activity and performance. This limits planning and development of seven-day pharmacy services. Aim To assess the impact of a seven-day clinical pharmacy service on dispensary activity and performance, at the main site of a tertiary-referral teaching hospital. Methods A seven-day clinical pharmacy service was implemented in October 2021. Prior to this, pharmacy services were largely dispensary-based with clinical pharmacy services for acute and neurosciences admission and limited ward-based services in other specialities. At implementation, clinical pharmacy technicians and pharmacists (n=16) provided patient-facing pharmaceutical care for 7.5-hours/day across all specialities over the weekend; this included medicines reconciliation, preparation of discharge-medication lists, independent prescribing, counselling and clinical review of prioritised patients. The weekend dispensary staffing, skill-mix and shift patterns were redesigned to facilitate staff release from the dispensary rota. Dispensing activity data were obtained from Ascribe for six months pre- and post-implementation (April 2021-March 2022). Data were categorised as inpatient/discharge and the mean number of items dispensed per month analysed using Microsoft Excel. Discharge turnaround performance was calculated as percentage of discharge prescriptions dispensed within two-hours of dispensary receipt and obtained from the Prescription Tracking System. Verbal staff feedback was sought 4-months post-implementation. The study was deemed a service evaluation by the Pharmacy Research and Audit Group and so ethical approval was not required. Results Twelve dispensing staff and one pharmacist were rostered to one of three daily 3.75-hour dispensary shift patterns. Following implementation, mean total inpatient dispensing activity increased from 12799 to 13250 items/month (3.5% increase) and mean weekend activity from 2184 to 2677 items/month (22.6% increase). Mean weekday inpatient activity was stable at 10615 to 10573 items/month. The mean discharge dispensing activity increased from 9065 to 9837 items/month (8.5% increase): mean weekday discharge from 8498 to 8622 items/month (1.5% increase); mean weekend activity from 569 to 1215 items/month (114% increase). Discharge turnaround performance remained stable with 85% discharge prescriptions dispensed within 2-hours, versus 84% pre-implementation. Weekday performance also remained stable - from 84% to 83% and the weekend performance increased from 85% to 92%. Dispensary staff fed-back that weekend shift patterns were effective, activity was manageable and shifts usually ran smoothly and finished on time. Discussion/Conclusion Introduction of a seven-day clinical pharmacy service led to an increase in weekend dispensary activity, which was not offset by decrease in weekday activity. Importantly, the dispensary performance was not negatively impacted and weekend discharge performance improved. Increases could be because of weekend medicines reconciliation, pro-active medication ordering and pharmacist-led preparation of discharge-medicine lists. Dispensary activity in Winter 2020 was atypical because of COVID-19, thus it was not feasible to compare data. Further review, including 12 months data would reduce impact of seasonal variations in NHS activity. Limitations include that patient data including length of stay and time to discharge were not within scope.

Accelerometer-measured physical activity and sedentary time among children and their parents in the UK before and after COVID-19 lockdowns: a natural experiment

BackgroundRestrictions due to the coronavirus disease 2019 (COVID-19) pandemic reduced physical activity provision for both children and their parents. Recent studies have reported decreases in physical activity levels during lockdown restrictions, but these were largely reliant on self-report methods, with data collected via unrepresentative self-report surveys. The post-pandemic impacts on children’s activity levels remain unknown. A key question is how active children become once lockdown restrictions are lifted.MethodsActive-6 is a repeated cross-sectional natural experiment. Accelerometer data from 1296 children aged 10–11 and their parents were collected in 50 schools in the Greater Bristol area, UK in March 2017-May 2018 (pre-COVID-19 comparator group), and compared to 393 children aged 10–11 and parents in 23 of the same schools, collected in May-December 2021. Mean minutes of accelerometer-measured moderate-to-vigorous physical activity (MVPA) were derived for weekdays and weekend and compared pre- and post-lockdown via linear multilevel models.ResultsAfter adjusting for seasonality, accelerometer wear time and child/parent demographics, children’s mean weekday and weekend MVPA were 7.7 min (95% CI: 3.5 to 11.9) and 6.9 min (95% CI: 0.9 to 12.9) lower in 2021 than in 2018, respectively, while sedentary time was higher by 25.4 min (95% CI: 15.8 to 35.0) and 14.0 min (95% CI: 1.5 to 26.5). There was no evidence that differences varied by child gender or household education. There was no significant difference in parents’ MVPA or sedentary time, either on weekdays or weekends.ConclusionsChildren’s MVPA was lower by 7–8 min/day in 2021 once restrictions were lifted than before the pandemic for all groups, on both weekdays and weekends. Previous research has shown that there is an undesirable age-related decline in children’s physical activity. The 8-min difference reported here would be broadly comparable to the decline that would have previously been expected to occur over a three-year period. Parents’ physical activity was similar to pre-pandemic levels. Our results suggest that despite easing of restrictions, children’s activity levels have not returned to pre-pandemic levels. There is an urgent need to understand why these changes have occurred and how long they are maintained.

Impact of screen time during COVID-19 on eating habits, physical activity, sleep, and depression symptoms: A cross-sectional study in Indian adolescents.

This study attempted to address the limited knowledge regarding the impact of screen time (ST) on lifestyle behaviors in Indian adolescents during the ongoing COVID-19 pandemic. The objectives were to 1) evaluate frequency and duration of using screens, and screen addiction behaviors in 10-15 years old adolescents in Mumbai during the COVID-19 pandemic and 2) examine the association of ST with lifestyle behaviors- eating habits, snacking patterns, physical activity (PA) levels, sleep quality and depression symptoms. An online survey was completed between January and March 2021. Eating habits, snacking patterns, time spent in different screen-based activities, and screen addiction behaviors were reported. The PA levels, sleep quality, and depression symptoms were evaluated using the Physical Activity Questionnaire for Children/Adolescents (PAQ C/A), Pittsburg Sleep Quality Index (PSQI), and Patient Health Questionnaire-2 (PHQ-2) respectively. Multiple linear regression analyses were performed to determine the impact of ST on lifestyle behaviors. Adolescents (n = 1298, Mage 13.2(1.1), 53.3% boys) reported the mean weekday and weekend ST as 442.3 (201.5) minutes/d and 379.9 (178.2) minutes/d respectively. Overall, 33.4% spent > 6hours/d for studying or doing homework, 65.4% used social networking sites for at least 2-3 hours/d, and 70.7% agreed that ST had taken up the majority of their leisure time. Only 12% engaged in moderate to vigorous PA (PAQ C/A scores <2). More than half (52.5%) reported PSQI >5 indicating poor sleep quality and 8.6% scored ≥ 3 on PHQ-2 to suggest a risk of depression. A higher ST was associated with lower PA and increased sleep problems and a greater screen addiction was inversely associated with the eating habit, PA, and sleep-related variables. The study draws attention to a high prevalence of excess ST and its impact on eating habits, PA levels, and sleep quality in Indian adolescents during the COVID-19 pandemic. Targeted health promotion interventions that encourage judicious use of screens for education and entertainment and emphasize the adverse health effects of excess ST are required.

Exposure to phthalates in relation to sleep duration and social jetlag among adolescent boys and girls in Mexico City

BACKGROUND AND AIM: Emerging research has demonstrated the importance of environmental toxicants, such as phthalates, for sleep health, as they may disrupt neuronal sleep regulation circuitry. However, the impact of high-molecular-weight (HMW) versus low-molecular-weight (LMW) phthalates remains unknown. Among Mexican adolescents, we evaluated the association between exposure to HMW and LMW phthalates with sleep duration and social jetlag (a circadian marker that measures the discrepancy between weekend and weekday sleep duration). METHODS: Participants included 413 adolescents from the Early Life Exposures in Mexico to ENvironmental Toxicants (ELEMENT) study. In 2015, urinary concentrations of 13 phthalates were measured from spot urine samples, and sleep duration was assessed with wrist-actigraph devices over 7consecutive days. We examined associations between phthalates with mean weekday and weekend sleep duration and social jetlag using linear regression models, adjusted for specific-gravity, sex, age, BMI z-score, total energy intake, caffeine intake, and physical activity. RESULTS:The mean (SD) age was 15.6 (2.0) years; 53.5% were girls. The mean (SD) sleep duration was 8.4 (1.2) hr/night on weekdays and 9.0 (1.3) hr/night on weekends. In adjusted models, each IQR increase in the HMW phthalate, mono-(2-ethyl-5-oxohexyl) phthalate was associated with a 13.3 minute (95%CI: -26.3, -0.41; p 0.05) lower social jetlag, and each IQR increase in mono-benzyl phthalate was associated with an 8.0 minute (95% CI: -16.8, -0.72; p 0.05) shorter sleep duration on weekends. Among LMW phthalates, we found that each IQR increase in monoethyl phthalate was associated with an 8.6 minute (95% CI: -17.9, -0.63; p 0.05) shorter sleep duration on weekends and a 15.3 minute (95% CI: -29.0, -1.6; p 0.05) lower social jetlag. CONCLUSIONS:In contrast to other literature, higher phthalate exposure was related to shorter weekend sleep duration and lower social jetlag among Mexican adolescents, sleep characteristics that may be indicative of better sleep health. KEYWORDS: phthalates; environmental epidemiology; adolescent sleep health; social jetlag, sleep duration, wrist-actigraphy

Characterizing Seven Day 24-hour Urinary Hydration Markers In College-aged Men And Women

Maintaining a day-to-day state of euhydration is advantageous for acute and long-term health. However, little data exists examining 24h hydration status in free-living emerging adults (18 – 25y). PURPOSE: Thus, the purpose of this study was to assess 24h urinary hydration markers across 7 days in male and female college students. METHODS: Eighteen participants (male, n=11; female, n=7; mean±SD; age, 23±3y; height, 164.6±15.3cm, body mass, 73.48±15.86kg; body fat, 19.4±9.4%) provided a 24-hour urine sample on 7 consecutive days. Measures of 24h urine volume (UVOL), urine osmolality (UOSM), urine specific gravity (USG), and urine color (UCOL) were assessed each day. Differences in 24h urinary hydration markers between weekdays and weekend days were assessed. RESULTS: Across 7 days, mean UVOL, UOSM, USG, and UCOL was 1.59±0.89 L, 628±284 mOsm•kg-1, 1.020±0.007, 3.8±1.6, respectively. There were no differences (all p > 0.05) between weekday and weekend days for mean UVOL (1.61±0.82 vs. 1.56±0.72 L) , UOSM (626±270 vs. 627±235 mOsm•kg-1), USG (1.020±0.007 vs. 1.020±0.006), and UCOL (3.8±1.4 vs. 3.8±1.5), respectively. Mean weekend day measures of UVOL (adj R2 = 0.507, p=0.001), UOSM (adj R2 = 0.547, p<0.001), USG (adj R2 = 0.551, p<0.001), and UCOL (adj R2 = 0.608, p<0.001) were all significantly associated with mean weekday measures. CONCLUSION: Our results suggest that, in this sample population of college students, individuals tended to have stable 24-hour urinary hydration measures across weekdays and weekend days. Despite finding relative stability in 24 hour urinary hydration markers across a week, we are unable to discuss factors associated with day-to-day variation in these measures. Integrating other factors such as previous personal and family medical history, physical activity, dietary intake, body composition, racial/ethnic background, and socioeconomic status may further elucidate variations in day-to-day hydration status and the role hydration plays in emerging adults on health.

4:03 PM Abstract No. 334 Reduction of unplanned late hours in inpatient procedure scheduling by forecasting with the Facebook Prophet algorithm

Inability to predict daily and monthly variation in interventional radiology (IR) inpatient needs is a major cause of unanticipated late hours and staff dissatisfaction. We tested the hypothesis that forecasting inpatient demand with the Facebook Prophet algorithm would reduce unplanned late inpatient hours compared to our standard scheduling method. A total of 12,483 inpatient cases performed between 2016 and 2019 were analyzed. For 2019, inpatient time was computed using two methods: (1) standard method (mean inpatient time from previous year) or (2) Facebook Prophet algorithm (a forecasting method based on an additive model where components of non-linear trend, seasonality, and holiday effects are complemented by a probabilistic model). Actual allocated inpatient time was performed using the Prophet forecast. We computed the difference between actual total inpatient hours performed and expected total inpatient hours using both methods from January to August 2019. One sample T-tests were used to compare deviations from expected values. Mean weekday inpatient hours were 22.9 and 23.3 in 2017 and 2018, respectively. Using the standard method, for 2019 the monthly planned inpatient time would be 23.5 hours. Using the Prophet algorithm, monthly planned inpatient time ranged from 24.1 (May) to 26.7 (August) hours, correctly anticipating both the upward trend, as well as the seasonality peak in August. Using the standard method, there was a significant deviation from the expected inpatient time in 2019 (P <0.001) in the months of March (-2.8 hours/d, P <0.001), April (-3.8 hours/d P <0.02), July (-3.5 hours/d, P <0.001), and August (-3.1 hours/d, P <0.02). Using the Prophet algorithm, there was no significant deviation from expected inpatient time in 2019 (P <0.052) or in the months of March (-1.1 hours/d, P <0.12), April (-1.2 hours/d, P <0.41), July (-0.68 hours/d, P <0.44), and August (-0.9 hours/d, P <0.93). Forecasting expected demand with the Facebook Prophet algorithm can significantly reduce unplanned inpatient hours, especially during months with high demand for inpatient procedures.

Childhood and adolescent television viewing and internalising disorders in adulthood

Time spent watching television during childhood and adolescence has been linked to socio-emotional and physical health problems in adulthood. It is unclear whether excessive television viewing is a risk factor for internalising mental health disorders such as anxiety and depression. Longitudinal associations between television viewing in childhood and adult diagnoses of anxiety and depression were investigated in a population-based birth cohort from Dunedin, New Zealand. Mean weekday television viewing time was reported by parents and adolescents between ages 5 and 15 years (1977–1987). Diagnoses of any anxiety disorder and major depression were made using standard criteria from symptoms reported for the previous year at ages 18, 21, 26, 32, and 38 years (between 1990 and 2012). Analyses adjusted for sex, parent and teacher reports of worry/fearfulness at age 5, and socioeconomic status during childhood. Diagnoses were counted if present at any of these assessments. Approximately half of all participants met criteria for anxiety disorder or depression during at least one adult assessment. Participants who had watched more television during childhood and adolescence were more likely to have a diagnosis of anxiety in sex-adjusted analyses (OR [95% CI] 1.22 [1.05, 1.41], p = 0.01), although this association weakened after adjustment for early childhood worry/fearfulness and socioeconomic status. There was no association between television viewing and depression in sex- or fully-adjusted analyses. Excessive television viewing during childhood and adolescence may be a risk factor for developing an anxiety disorder in adulthood, but does not appear to influence the long-term risk for major depression.

Central heating settings and heating energy demand in low energy social housing in the United Kingdom

This paper compares the central heating settings and the heating energy use performance of six flats and two houses built to low energy standards (Code for Sustainable Homes Levels 4 and 5) with a near identical flat and house built to minimum compliance only (2006 Building Regulations). As low energy houses are only recently emerging in the United Kingdom’s social housing stock, and even fewer are subject to Post Occupancy Evaluation, little is known about their performance in terms of heating behaviour and energy demand. The results show that in general, the mean weekday and weekend setpoint temperatures, heating durations and heating energy use are lower in the low energy dwellings compared to the building regulations dwellings.

Assessment of physical activity by pedometer in Polish preschool children

PurposeThe aim of the study was to evaluate and compare the physical activity patterns of preschoolers aged 6–7 years.MethodsA sample of 221 preschool children (116 boys and 105 girls) aged 6 (5.92 ± 0.30) and 7 (6.91 ± 0.25) years was recruited. Physical activity was assessed over 7 consecutive days by using pedometers to determine step counts (steps/day). Accrued anthropometric data included height, mass, and BMI. Data were compared with ANOVA to determine any significant differences between age and sex groups and the part of the week (weekday/weekend); intergroup differences were evaluated with Fisher's LSD test. A &lt; 0.05 level of significance was adopted for all statistical tests.ResultsNo significant differences were found between the age groups (6- and 7-year olds). Physical activity over the 7-day period was significantly greater in the boys (13318 ± 2354 steps/day) than girls (12300 ± 2750 steps/day). Mean weekday step counts were greater among boys (13800 ± 2458 steps/day) than girls (12587 ± 2802 steps/day); this difference was statistically significant. Mean weekend steps were 12112 ± 3467 and 11579 ± 3930 steps/day for the boys and girls, respectively. Mean weekday steps were significantly greater (&lt;i&gt;p&lt;/i&gt; &lt; 0.001) than mean weekend steps in both groups. The recommendation of 12000 steps/day was met by 60.6% of the sample (69.0% boys, 51.4% girls).ConclusionsSex differences in physical activity patterns were observed in the sample of preschool children. Boys, compared with girls, were characterized with a higher physical activity level on both weekdays and weekend days. Physical activity for both sexes was lower on weekend days than weekdays. The results indicate the need for improved health literacy among parents on current recommended physical activity guidelines and the suitability of a pedometer-based assessment method.

Associated factors of sitting time in Japanese junior high school students

Previous research suggest that sedentary behavior is emerging as a risk behavior for chronic disease and mortality (Katzmarzyk et al., 2009; Thorp et al., 2012). But it is unknown what factors influence sedentary behavior in Japanese adolescents. Therefore, the aim of this study was to clarify the associated factors of sitting time in Japanese adolescents. Participants were 140 (mean age: 13.0 ± 0.9, female: 49.3%, mean body mass index [BMI]: 19.7 ± 3.0) 1st to 3rd grade (7th to 9th grade in USA) students of public junior high schools near Saga area in Japan. All students completed the questionnaires. Sitting time and moderate-to-vigorous physical activity (MVPA) was measured by the International Physical Activity Questionnaire. Physical fitness scores and academic performances (school grade) were received from school records. The physical fitness tests that were authorized by Japanese Ministry of Education, Culture, Sports, Science and Technology were used. The sum total of the 8 subjects grades (Japanese, social studies, math, science, English, music, arts, physical education) were used as academic performance scores. Mean weekday and weekend sitting time were 442.8 ± 217.5 min and 485.8 ± 255.3 min, respectively. Using multiple regression analysis that controlled for several covariates (age, gender, BMI, physical fitness score, MVPA), weekday sitting time was significantly associated with gender (beta = 0.244) and academic performance (beta = 0.286), and weekend sitting time was significantly associated with gender (beta = 0.217) only. These results suggest that less weekday sitting time was associated with being male, greater physical fitness and worse academic performances among Japanese junior high school students.

School travel mode, parenting practices and physical activity among UK Year 5 and 6 children.

BackgroundSchool travel mode and parenting practices have been associated with children’s physical activity (PA). The current study sought to examine whether PA parenting practices differ by school travel mode and whether school travel mode and PA parenting practices are associated with PA.Methods469 children (aged 9-11) wore accelerometers from which mean weekday and after-school (3.30 to 8.30 pm) minutes of moderate-to-vigorous intensity PA (MVPA) and counts per minute (CPM) were derived. Mode of travel to and from school (passive vs. active) and PA parenting practices (maternal and paternal logistic support and modelling behaviour) were child-reported.ResultsChildren engaged in an average of 59.7 minutes of MVPA per weekday. Active travel to school by girls was associated with 5.9 more minutes of MVPA per day compared with those who travelled to school passively (p = 0.004). After-school CPM and MVPA did not differ by school travel mode. There was no evidence that physical activity parenting practices were associated with school travel mode.ConclusionsFor girls, encouraging active travel to school is likely to be important for overall PA. Further formative research may be warranted to understand how both parental logistic support and active travel decisions are operationalized in families as a means of understanding how to promote increased PA among pre-adolescent children.

Long Term Black Carbon Measurements at Two Urban Locations in New York

Measurements of PM2.5 black carbon (BC) over an 8–9 year period are used to characterize temporal patterns at sites in New York City (NYC) and Rochester, NY. Annual mean BC at the NYC location ranges from 1.4 to 2.0 μg/m 3 , whereas mean concentrations at Rochester are approximately a factor of 2–3 lower. BC amounts to 15–20% of PM2.5 mass in NYC compared to 7–10% at Rochester. Seasonal patterns reveal the highest BC concentrations in NYC from November to February versus June to November at Rochester. At both locations, mean weekday (Monday-Friday) BC concentrations are statistically higher compared to weekends (Saturday and Sunday). Weekday BC diurnal profiles exhibit a morning peak between 6–10 AM EST followed by an afternoon minimum, with a secondary peak in the late evening. Sunday BC diurnal profiles show highest concentrations at night, from 8 PM to 2 AM. These patterns are consistent with vehicle counts on nearby roadways and boundary layer dynamics at both locations. Simultaneous measurements of BC at 370 and 880 nm show an enhancement in BC370 relative to the BC880 from October to March. This enhanced signal is most evident at Rochester during late evening and early morning hours (8 PM to 4 AM) on weekends, and is attributed to UV absorbing species (such as wood smoke markers) in the ambient particle mixture. At the NYC site, the levels of Nickel (Ni) and Cobalt (Co) in PM10 are elevated during the heating season due to residual oil combustion. The long term datasets are used to explore the seasonal relationship between BC880 and EC at both sites.

P76 The effect of outside temperature on daily physical activity in COPD patients

IntroductionCOPD is characterised by breathlessness, leading to reduced physical activity. Breathlessness varies dependent upon the degree and intensity of physical activity (1). Common logic dictates that weather variation such as...

Comparison of Self-Reported Week-Day and Weekend-Day Sitting Time and Weekly Time-Use: Results from the Australian Longitudinal Study on Women’s Health

The study of sedentary behavior is a relatively new area in population health research, and little is known about patterns of sitting time on week-days and weekend-days. To compare self-reported week-day and weekend-day sitting time with reported weekly time spent in other activities. Data were from 8,717 women born between 1973 and 1978 ('younger'), and 10,490 women born between 1946 and 1951 ('mid-age') who completed surveys for the Australian Longitudinal Study on Women's Health in 2003 and 2001, respectively. They were asked about time spent sitting on week-days and weekend-days. The women were also asked to report time spent in employment, active leisure, passive leisure, home duties, and studying. Mean week-day and weekend-day sitting times were compared with time-use using analysis of variance. Younger women sat more than mid-aged women, and sitting time was higher on week-days than on weekend-days in both cohorts. There were marked positive associations between week-day and weekend-day sitting times and time spent in passive leisure in both cohorts, and with time spent studying on week-days for the younger women. Week-day sitting time was markedly higher in women who reported >35h in employment, compared with those who worked <35h. In contrast, there were inverse associations between sitting time and time spent in home duties. Associations between sitting and active leisure were less consistent. Although week-day sitting time was higher than weekend-day sitting time, the patterns of the relationships between week-day and weekend-day sitting and time-use were largely similar, except for time spent in employment.

Associations of executive function with sleepiness and sleep duration in adolescents.

Sleep deprivation and sleepiness are associated with poorer school performance, impaired neurobehavioral functioning, and behavioral problems. To determine if adolescents with high levels of sleepiness or short sleep duration have impaired executive functioning. Ours was a cross-sectional analysis of data from 236 healthy adolescents in a community-based cohort study. Sleepiness was measured by using a modified version of the Epworth Sleepiness Scale. Participants underwent 5- to 7-day wrist actigraphy at home before overnight polysomnography. Exposure variables were excessive sleepiness (Epworth Sleepiness Scale > or = 11) and weekday mean sleep duration. The main outcome measures were the global executive composite scale from the Behavior Rating Inventory of Executive Function and the tower test-total achievement score from the Delis-Kaplan Executive Functioning System. Participants (N = 236) were 13.7 +/- 0.8 years of age, and 52.1% were boys. Mean weekday sleep duration was 7.70 +/- 1.03 hours; 11% slept <6.5 hours on average on weekdays, and 26% reported excessive sleepiness. In unadjusted analyses, sleepy adolescents had poorer executive functioning on the Behavior Rating Inventory of Executive Function global executive composite scale and the Delis-Kaplan Executive Functioning System tower test-total achievement. Analyses adjusted for potential confounders resulted in a modest attenuation of the association with the Behavior Rating Inventory of Executive Function and a larger attenuation for the Delis-Kaplan Executive Functioning System. Caregiver education modified the association between sleepiness and the Behavior Rating Inventory of Executive Function outcomes. Among sleepy adolescents, those with less-educated caregivers had greater impairment on the Behavior Rating Inventory of Executive Function global executive composite scale. Sleep duration was not significantly associated with executive functioning outcomes. Decrements in selected executive function scales are associated with subjective sleepiness, but not sleep duration, in adolescents. The association between sleepiness and executive functioning is strongest among adolescents with primary caregivers who have lower levels of education, suggesting an increased susceptibility. Pediatricians and public health officials should consider sleepiness as a potentially important contributor to adolescent functioning.

Pedometer-determined physical activity and active transport in girls

BackgroundIt is well established that the risk of insufficient physical activity is greater in girls than in boys, especially during the adolescent years. The promotion of active transport (AT) to and from school has been posited as a practical and convenient solution for increasing girls' total daily activity. However, there is limited information describing the associations between AT choices and girls' physical activity across a range of age, ethnic, and socioeconomic groups. The objectives of this study were to (1) investigate physical activity patterns in a large multiethnic sample of female children and adolescents, and to (2) estimate the physical activity associated with AT to and from school.MethodsA total of 1,513 girls aged 5–16 years wore sealed multiday memory (MDM) pedometers for three weekdays and two weekend days. The ethnic composition of this sample was 637 European (42.1%), 272 Pacific Island (18.0%), 207 East Asian (13.7%), 179 Maori (11.8%), 142 South Asian (9.4%), and 76 from other ethnic groups (5%). Pedometer compliance and school-related AT were assessed by questionnaire.ResultsMean weekday step counts (12,597 ± 3,630) were higher and less variable than mean weekend steps (9,528 ± 4,407). A consistent decline in daily step counts was observed with age: after adjustment for ethnicity and SES, girls in school years 9–10 achieved 2,469 (weekday) and 4,011 (weekend) fewer steps than girls in years 1–2. Daily step counts also varied by ethnicity, with Maori girls the most active and South Asian girls the least active. Overall, 44.9% of participants used AT for school-related travel. Girls who used AT to and from school averaged 1,052 more weekday steps than those who did not use AT. However, the increases in steps associated with AT were significant only in older girls (school years 5–10) and in those of Maori or European descent.ConclusionOur data suggest that adolescent-aged girls and girls of Asian descent are priority groups for future physical activity interventions. While the apparent benefits of school-related AT vary among demographic groups, promoting AT in girls appears to be a worthwhile strategy.

Weekday/Weekend Differences in Ambient Air Pollutant Concentrations in Atlanta and the Southeastern United States

The authors quantified changes between mean weekday and weekend ambient concentrations of ozone (O3) precursors (volatile organic compounds [VOC], carbon monoxide [CO], nitric oxide, and oxides of nitrogen [NOx]) in Atlanta and surrounding areas to observe how weekend precursor emission levels influenced ambient O3 levels.The authors analyzed CO, nitric oxide (NO), and NOx measurements from 1998 to 2002 and speciated VOC from 1996 to 2003. They observed a strong weekend effect in the Atlanta region, with median daytime (6:00 a.m. to 3:00 p.m. Eastern Standard Time) decreases of 62%, 57%, and 31%, respectively, in the ambient levels of NO, NOx,and CO from Wednesdays to Sundays, during the ozone season (March to October). They also observed significant decreases in ambient VOC levels between Wednesdays and Sundays, with decreases of 28% for the sum of aromatic compounds and 19% for the sum of Photochemical Assessment Monitoring Stations target compounds. Despite large reductions in O3 precursor levels on weekends, day-of-week differences in O3 mixing ratios in and near Atlanta were much smaller. Averaging overall O3-season days, the 1-hr and 8-hr mean peak daily O3 maxima on Sundays were 4.5% and 2.3% lower, respectively, than their mean levels on Wednesdays (median of 14 site differences), with no sites showing statistically significant Wednesday-to-Sunday differences. When restricted to high-O3 days (highest 3 peak O3 days per day of week per site per year), the 1-hr and 8-hr Sunday O3 mixing ratios were 11% and 10% lower, respectively, than their mean peak levels on Wednesdays (median of 14 site differences), with 6 of 14 sites showing statistically significant Wednesday-to-Sunday differences. The analyses of week-day/weekend differences in O3 precursor concentrations show that different emission reductions than normally take place each weekend will be required to achieve major reductions in ambient ozone levels in the Atlanta area.

Differences between Weekday and Weekend Air Pollutant Levels in Southern California

Ambient air quality data were analyzed to empirically evaluate the effects of reductions of volatile organic compounds (VOCs) and oxides of nitrogen (NOx) emissions on weekday and weekend levels of ozone (O3; 1991–1998) and particulate NO3 - (1980–1999) in southern California. Despite significantly lower O3 precursor levels on weekends, 20 of 28 South Coast Air Basin (SoCAB) sites (28 of all 78 southern California sites) showed statistically significant higher mean O3 levels on Sundays than on weekdays (p < 0.01); 49 of the remaining 50 sites showed no significant differences between mean weekday and Sunday peak O3 levels. We also observed no statistically significant differences between mean weekday and weekend concentrations of particulate NO3 - or nitric acid (HNO3, the precursor of particulate NO3 -). Averaged over sites, the mean Sunday NOx and nonmethane hydrocarbon concentrations were 25–41% and 16–30% lower, respectively, than on weekdays. Site-to-site differences between weekend and weekday mean peak hourly O3 levels were related to whether O3 formation was limited by the availability of NOx. A thermodynamic equilibrium model predicts that particulate NO3 - levels would decrease in response to a reduction of HNO3, and that particulate ammonium NO3 - formation was not limited by the availability of ammonia. The similarity of mean weekday and weekend levels of NO3 - therefore did not result from limitations on the formation of particulate NO3 - from its precursor, HNO3.

Spatial mapping of VOC and NO x-limitation of ozone formation in central California

Ambient aerometric data were used to predict whether ozone formation at specific times and locations in central California was limited by the availability of volatile organic compounds (VOC) or oxides of nitrogen (NO x ). The predictions were compared with differences between mean weekday and weekend peak ozone values. The comparison with weekend and weekday ozone levels provided a means for empirically investigating the effects of VOC and NO x reductions on ozone formation, because the relative proportions and levels of ozone precursor species were significantly different on weekends than on weekdays. Weekend NO x levels averaged 27 percent lower than weekday levels at the time of the peak ozone hour. Daytime weekend levels of VOC species were also consistently lower than weekday values throughout the region, though the differences between weekends and weekdays were not always statistically significant ( p<0.05). Site-to-site differences between weekend and weekday mean peak hourly ozone were related to whether ozone formation was VOC- or NO x -limited.