Theodora Pouliou

How active are our children? Findings from the Millennium Cohort Study

Objective To describe levels of physical activity, sedentary time and adherence to Chief Medical Officers (CMO) physical activity guidelines among primary school-aged children across the UK using objective accelerometer-based measurements. Design Nationally representative prospective cohort study. Setting Children born across the UK, between 2000 and 2002. Participants 6497 7-year-old to 8-year-old singleton children for whom reliable accelerometer data were available for at least 10 h a day for at least 2 days. Main outcome measures Physical activity in counts per minute (cpm); time spent in sedentary and moderate-to-vigorous intensity physical activity (MVPA); proportion of children meeting CMO guidelines (≥60 min/day MVPA); average daily steps. Explanatory measures Gender, ethnicity, maternal current/most recent occupation, lone parenthood status, number of children in the household and country/region of residence. Results The median daily physical activity level was 595 cpm (IQR 507, 697). Children spent a median of 60 min (IQR 47–76) in MVPA/day and were sedentary for a median of 6.4 h/day (IQR 6–7). Only 51% met CMO guidelines, with girls (38%) less active than boys (63%). Children took an average of 10 229 (95% CI (8777 to 11 775)) steps each day. Children of Indian ethnicity were significantly less active overall than all other ethnic groups. Children of Bangladeshi origin and those living in Northern Ireland were least likely to meet CMO guidelines. Conclusions Only half of 7-year-old children in the UK achieve recommended levels of physical activity, with significant gender, ethnic and geographic variations. Longitudinal studies are needed to better understand the relevance of these (in)activity patterns for long-term health and well-being. In the meantime population-wide efforts to boost physical activity among young people are needed which are likely to require a broad range of policy interventions.

Individual and socio-environmental determinants of overweight and obesity in Urban Canada

Overweight/obesity represent a significant public health problem in Canada and abroad. The objective of this paper is to identify potential associations between overweight/obesity and individual as well as socio-environmental determinants. The data sources used are the 2003 Canadian Community Health Survey and the Desktop Mapping Technologies Incorporated database. Geographical Information Systems are first employed to create neighbourhood-level variables such as neighbourhood walkability and fast food accessibility. Multivariate analysis is then applied to estimate the relative effects of individual- and neighbourhood-level risk-factors of overweight/obesity. Results demonstrate the important role of the built-environment after adjustment for demographic, socio-economic and behavioural characteristics. Findings support the rationale that reversing current trends will require a multifaceted public health approach where interventions are developed from the individual- to the neighbourhood-level, with a particular focus on altering obesogenic environments.

Parental and offspring adiposity associations: Insights from the 1958 British birth cohort

Background/aims: Parent–offspring adiposity associations are well-established: offspring of obese parents have elevated risks of overweight/obesity. The aim of studies based on the 1958 British birth cohort has been to gain insights into explanations of these associations, such as whether parent–offspring BMI associations are due to offspring lifestyles or depend on socio-economic conditions. Methods: All major studies on intergenerational adiposity associations in the three generations of the 1958 birth cohort were reviewed. In addition, BMI data for parents (G1) and the cohort (G2) were analysed stratified by social class. Results: BMI of G1 and G2 were correlated both when offspring were children and in mid-adulthood: a 1 kg/m2 higher parental BMI was associated with an average 0.24–0.35 kg/m2 higher offspring (mothers/fathers vs sons/daughters) BMI at 45 years. Associations were little affected by adjustment for lifestyle and socio-economic factors, but varied by social class: average BMI gain in offspring relative to parents was greater in lower classes, e.g. for males vs fathers by 3.6 and 2.5 kg/m2 in classes IV&V and I&II, respectively. Parent–offspring BMI associations were stronger for recent (G2 and G3) than older (G1 and G2) generations. Conclusions: Parent–offspring associations in BMI were not explained by offspring lifestyles, but varied over successive generations and by social class, suggesting that intergenerational transmission of adiposity at a population level is modifiable rather than immutable.

Physical activity and sedentary behaviour at different life stages and adult blood pressure in the 1958 British cohort

Objectives: To investigate whether physical activity or sedentary behaviour at different life stages is associated with blood pressure (BP) in mid-adulthood; activity levels have accumulative associations with BP; and adult body mass index (BMI) mediates associations. Methods: Information on activity and television-viewing was available at several ages (23, 33, 42, 45 years) and BP at 45 years for the 1958 British birth cohort (n = 9927). Associations were examined with and without adjustment for covariates. Results: Active adults, generally, had lower mean systolic and diastolic BP and risk of hypertension than nonactive, although varying by age. After adjustment for covariates, systolic and diastolic BP for active men at 23 years or at 45 years were 1–2 mmHg lower; similar associations were seen for women active at 33 years. Some but not all associations attenuated with further adjustment for BMI: odds ratio (OR) for hypertension associated with 23 years activity changed from 0.82 [95% confidence interval (CI) 0.74, 0.91] to 0.79 (0.70, 0.90) after BMI adjustment. Independent associations of activity at more than one age were found, such that prevalence of hypertension was higher in men active at 23 years but not at 45 years, than men sustaining activity (39 vs. 31%). Sitting at work was unrelated to BP, but there was a trend of higher BP with greater television-viewing: for example risk of hypertension was higher by 10–12% per h/day television-viewing at 45 years after adjustment for covariates, attenuating after allowance for BMI. Conclusion: Our study suggests that there are benefits to BP of becoming and sustaining active lifestyles and minimizing television-viewing over many years of adulthood, with a mediating role for BMI.

Assessing the health impacts of air pollution: a re-analysis of the Hamilton children's cohort data using a spatial analytic approach

The objective of this paper was to reassess childrens exposure to air pollution as well as investigate the importance of other covariates of respiratory health. We re-examined the Hamilton Childrens Cohort (HCC) dataset with enhanced spatial analysis methods, refined in the approximately two decades since the original study was undertaken. Childrens exposure to air pollution was first re-estimated using kriging and land-use regression. The land-use regression model performed better, compared to kriging, in capturing local variation of air pollution. Multivariate linear and logistic regression analysis was then applied for the study of potential risk factors for respiratory health. Findings agree with the HCC study-results, confirming that childrens respiratory health was associated with maternal smoking, hospitalization in infancy and air pollution. However, results from this study reveal a stronger association between childrens respiratory health and air pollution. Additionally, this study demonstrated associations with low-income, household crowding and chest illness in siblings.

Physical (in)activity over 20 y in adulthood: Associations with adult lipid levels in the 1958 British birth cohort

OBJECTIVES To investigate associations between physical (in)activity at different life-stages and lipids in mid-adulthood, examining the role of potential confounding and mediating factors, such as adiposity. METHODS Data from the 1958 British birth cohort (n=7824) were examined. Using linear regression, we analysed prospectively reported frequency of activity and TV-viewing (23, 33, 42 and 45 y) in relation to total, LDL-, HDL-cholesterol and triglycerides, at 45 y. RESULTS Activity at different ages was associated with HDL-cholesterol and triglycerides at 45 y: e.g. in men, a 1 day/week greater activity frequency at 42 y was associated with 0.006 mmol/L higher HDL-cholesterol and 1.4% lower triglycerides. Most associations attenuated, but were not entirely explained by adjustment for covariates (life-styles and socio-economic factors): e.g. among men, the estimated 2.0% lower triglycerides per 1 day/week greater frequency at 33 y reduced to 1.8% after adjustment. Among women, though not men, activity at both 23 and 45 y contributed cumulatively to HDL-cholesterol. For sedentary behaviour, associations were found for sitting at work: a 1 h/day greater sitting among men was associated with a 0.012 mmol/L lower HDL-cholesterol after adjustment for covariates. Associations were seen for TV-viewing: e.g. in men, a 0.04 mmol/L lower HDL-cholesterol and 5.9% higher triglycerides per hour/day greater TV-viewing at 45 y, attenuated, respectively, to 0.03 mmol/L and 4.6% after adjustment for covariates. Associations attenuated further after adjustment for current BMI. Associations for total and LDL-cholesterol were less consistent. CONCLUSION Activity and sedentary behaviour at different adult ages were associated with HDL-cholesterol and triglycerides in mid-adulthood. Associations were partly mediated by other life-style factors and by BMI.

Environmental influences on children's physical activity

Background This paper aims to assess whether 7-year-olds’ physical activity is associated with family and area-level measures of the physical and socioeconomic environments. Methods We analysed the association of environments with physical activity in 6497 singleton children from the UK Millennium Cohort Study with reliable accelerometer data (≥2 days and ≥10 h/day). Activity levels were assessed as counts per minute; minutes of moderate to vigorous activity (MVPA); and whether meeting recommended guidelines (≥60 min/day MVPA). Results Higher levels of childrens physical activity were associated with households without use of a car and with having a television in a childs bedroom (for counts per minute only). Aspects of the home socioeconomic environment that were associated with more childrens physical activity were lone motherhood, lower maternal socioeconomic position and education, family income below 60% national median, and not owning the home. Childrens activity levels were higher when parents perceived their neighbourhood as poor for bringing up children and also when families were living in the most deprived areas. Relationships were independent of characteristics such as childs body mass index and ethnic group. When adjusted for physical and socioeconomic correlates, the factors remaining significant in all outcomes were: household car usage and maternal education. Conclusions Although physical and socioeconomic environments are associated with children’s physical activity, much of the variation appears to be determined by the childs home socioeconomic circumstances rather than the wider environment where they live.

Sunshine, Sea, and Season of Birth: MS Incidence in Wales

Maternal sun exposure in gestation and throughout the lifetime is necessary for vitamin D synthesis, and living near the sea is a population level index of seafood consumption. The aim of this study was to estimate the incidence rate of multiple sclerosis (MS) in Wales and examine its association with sun exposure, coastal living, and latitude. The study used a database of MS hospital visits and admissions in Wales between 2002 and 2013. For the 1,909 lower layer super output areas (LSOAs) in Wales, coastal status, population, longitude/latitude, and average sunshine hours per day were obtained. Age-specific and age-standardised MS incidence were calculated and modelled using Poisson regression. The distribution of births by month was compared between MS cases and the combined England and Wales population. There were 3,557 new MS cases between 2002 and 2013, with an average annual incidence of 8.14 (95% CI: 7.69–8.59) among males and 12.97 (95% CI: 12.44–13.50) among females per 100,000 population. The female-to-male ratio was 1.86:1. For both sexes combined, the average annual incidence rate was 9.10 (95% CI: 8.80–9.40). All figures are age-standardized to the 1976 European standard population. Compared to the combined England and Wales population, more people with MS were born in April, observed-to-expected ratio: 1.21 (95% CI: 1.08–1.36). MS incidence varied directly with latitude and inversely with sunshine hours. Proximity to the coast was associated with lower MS incidence only in easterly areas. This study shows that MS incidence rate in Wales is comparable to the rate in Scotland and is associated with environmental factors that probably represent levels of vitamin D.

Objectively measured physical activity and sedentary behaviour in UK children of primary school age: a longitudinal cohort study

Abstract Background There is growing evidence of the health benefits of physical activity for young people, including reduced risk of obesity and improved psychological wellbeing. Conversely, sedentary behaviour is now recognised to increase the risk of later poor health. Patterns of physical activity and sedentary behaviour are established in early childhood. In July, 2011, the UK Chief Medical Officers released new guidelines for all young people, recommending engagement in moderate to vigorous intensity physical activity for at least 60 min every day, incorporation of vigorous intensity activities on at least 3 days each week, and minimising time spent being sedentary for extended periods. Information about the extent to which UK children of primary school age are meeting these recommendations is sparse. We measured time spent in different intensities of physical activity, and assessed adherence to guidelines, in a UK-wide representative sample of children of primary school age taking part in a longitudinal cohort study. We used accelerometer-based activity monitors because this approach allowed the frequency, intensity, and duration of free-living activity to be objectively measured. Methods Nearly 13 000 7-year-old children taking part in the UK Millennium Cohort Study consented to wear an Actigraph activity monitor during all waking hours for 7 days, apart from during bathing or other aquatic activities (eg, swimming). Valid accelerometer data (≥2 days, ≥6 h wear each day) were obtained from nearly 7000 singletons. For each child several variables were produced: mean daily min of sedentary (defined as 3841 cpm) activity. Time spent in moderate and vigorous activity was combined to establish adherence to activity guidelines. We fitted logistic regression models to compare adherence to guidelines according to individual (sex, ethnicity) and family (maternal social class, numbers of children in household, lone parenthood) factors, and country or region of residence. Findings On average, children accumulated 27 and 11 min per day of moderate and vigorous activity, respectively, and were sedentary for 5 h per day. Only 15% of all children achieved 60 min or more of daily moderate to vigorous intensity physical activity. Activity varied by ethnic group, with those of Indian and Bangladeshi origin the least active and black children the most active. Within adjusted analyses, significant differences were reported in adherence to activity guidelines between girls and boys (p Interpretation Only a small proportion of children of primary school age in the UK meet guidelines and are sufficiently active. A substantial part of their day is spent in sedentary behaviour and striking differences in activity are evident between boys and girls, different ethnic or social groups, and UK countries. Although we recognise the importance of some sedentary pursuits, such as reading and homework, measures to increase childrens engagement in physical activity are needed for social and health benefits. Funding The Wellcome Trust (grant 084686/Z/08/A).