Lynne M. Boddy

A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3–19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8–144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries. DOI: http://dx.doi.org/10.7554/eLife.13410.001

Associations between children's socioeconomic status, weight status, and sex, with screen-based sedentary behaviours and sport participation

OBJECTIVE The objective was to study associations between socioeconomic status (SES), weight status, and sex, with childrens participation in sedentary behaviours and sport. METHODS Children (aged 9-10 years; n = 6,337) completed a questionnaire to establish how long they spent in sedentary behaviours and sport participation during week days and weekend days. Height and weight were measured to calculate body mass index. Associations between dependent and independent variables were investigated using hierarchical loglinear analysis. RESULTS A significantly greater proportion of boys than girls spent > or = 1 h per weekday and weekend day watching television (TV) (p < 0.001), playing video games (p < 0.001), and participating in sport (p < 0.001). TV viewing and video gaming for > or = 1 h per day were inversely associated with SES (p = 0.001), whilst the greatest proportion of children participating in sport for > or = 1 h were in the highest SES quartile (p < 0.001). Overweight girls were more likely than normal weight girls to use the internet for > or = 1 h per weekend day (p < 0.001). CONCLUSIONS Relatively more lower SES children spent time in sedentary behaviours than sport participation. Weight status was not consistently associated with sedentary behaviours. Proportionately more boys than girls watched TV, played video games, and participated in sport, suggesting that boys find time for sedentary behaviours and physical activity. Efforts should be made to address inequalities in the prevalence of sedentary behaviours and sport participation for all children regardless of SES, weight status, or sex.

Cardiorespiratory fitness and body mass index of 9-11-year-old English children: A serial cross-sectional study from 1998 to 2004

Objective:To examine the changes over time in cardiorespiratory fitness and body mass index (BMI) of children.Design:Serial cross-sectional, population-based study.Setting:Primary schools in Liverpool, UK.Participants:A total of 15 621 children (50% boys), representing 74% of eligible 9–11-year olds in the annual school cohorts between 1998/9 and 2003/4, who took part in a 20m multi-stage shuttle run test (20mMST).Main outcome measures:Weight, height, BMI (kg/m2) and obesity using the International Obesity Taskforce definition.Results:Median (95% confidence interval) 20mMST score (number of runs) fell in boys from 48.9 (47.9–49.9) in 1998/9 to 38.1 (36.8–39.4) in 2003/4, and in girls from 35.8 (35.0–36.6) to 28.1 (27.2–29.1) over the same period. Fitness scores fell across all strata of BMI (P<0.001). Moreover, BMI increased over the same 6-year period even among children in fittest third of 20mMST.Conclusion:In a series of uniform cross-sectional assessments of school-aged children, BMI increased whereas cardiorespiratory fitness levels decreased within a 6-year period. Even among lean children, fitness scores decreased. Public health measures to reduce obesity, such as increasing physical activity, may help raise fitness levels among all children – not just the overweight or obese.

Wear compliance and activity in children wearing wrist and hip mounted accelerometers

PURPOSE This study aimed to 1) explore childrens compliance to wearing wrist- and hip-mounted accelerometers, 2) compare childrens physical activity (PA) derived from raw accelerations of wrist and hip, and 3) examine differences in raw and counts PA measured by hip-worn accelerometry. METHODS One hundred and twenty-nine 9- to 10-yr-old children wore a wrist-mounted GENEActiv accelerometer (GAwrist) and a hip-mounted ActiGraph GT3X+ accelerometer (AGhip) for 7 d. Both devices measured raw accelerations, and the AGhip also provided count-based data. RESULTS More children wore the GAwrist than those from the AGhip regardless of wear time criteria applied (P < 0.001-0.035). Raw data signal vector magnitude (r = 0.68), moderate PA (MPA) (r = 0.81), vigorous PA (VPA) (r = 0.85), and moderate-to-vigorous PA (MVPA) (r = 0.83) were strongly associated between devices (P < 0.001). GAwrist signal vector magnitude (P = 0.001), MPA (P = 0.037), VPA (P = 0.002), and MVPA (P = 0.016) were significantly greater than those from the AGhip. According to GAwrist raw data, 86.9% of children engaged in at least 60 min · d(-1) of MVPA, compared with 19% for AGhip. ActiGraph MPA (raw) was 42.00 ± 1.61 min · d(-1) compared with 35.05 ± 0.99 min · d(-1) (counts) (P = 0.02). ActiGraph VPA was 7.59 ± 0.46 min · d(-1) (raw) and 37.06 ± 1.85 min · d(-1) (counts; P = 0.19). CONCLUSIONS In children, accelerometer wrist placement promotes superior compliance than the hip. Raw accelerations were significantly higher for GAwrist compared with those for AGhip possibly because of placement location and technical differences between devices. AGhip PA calculated from raw accelerations and counts differed substantially, demonstrating that PA outcomes derived from cut points for raw output and counts cannot be directly compared.

Promoting healthy weight in primary school children through physical activity and nutrition education: a pragmatic evaluation of the CHANGE! randomised intervention study

BackgroundThis pragmatic evaluation investigated the effectiveness of the Children’s Health, Activity and Nutrition: Get Educated! (CHANGE!) Project, a cluster randomised intervention to promote healthy weight using an educational focus on physical activity and healthy eating.MethodsParticipants (n = 318, aged 10–11 years) from 6 Intervention and 6 Comparison schools took part in the 20 weeks intervention between November 2010 and March/April 2011. This consisted of a teacher-led curriculum, learning resources, and homework tasks. Primary outcome measures were waist circumference, body mass index (BMI), and BMI z-scores. Secondary outcomes were objectively-assessed physical activity and sedentary time, and food intake. Outcomes were assessed at baseline, at post-intervention (20 weeks), and at follow-up (30 weeks). Data were analysed using 2-level multi-level modelling (levels: school, student) and adjusted for baseline values of the outcomes and potential confounders. Differences in intervention effect by subgroup (sex, weight status, socio-economic status) were explored using statistical interaction.ResultsSignificant between-group effects were observed for waist circumference at post-intervention (β for intervention effect =−1.63 (95% CI = −2.20, -1.07) cm, p<0.001) and for BMI z-score at follow-up (β=−0.24 (95% CI = −0.48, -0.003), p=0.04). At follow-up there was also a significant intervention effect for light intensity physical activity (β=25.97 (95% CI = 8.04, 43.89) min, p=0.01). Interaction analyses revealed that the intervention was most effective for overweight/obese participants (waist circumference: β=−2.82 (95% CI = −4.06, -1.58) cm, p<0.001), girls (BMI: β=−0.39 (95% CI = −0.81, 0.03) kg/m2, p=0.07), and participants with higher family socioeconomic status (breakfast consumption: β=8.82 (95% CI = 6.47, 11.16), p=0.07).ConclusionsThe CHANGE! intervention positively influenced body size outcomes and light physical activity, and most effectively influenced body size outcomes among overweight and obese children and girls. The findings add support for the effectiveness of combined school-based physical activity and nutrition interventions. Additional work is required to test intervention fidelity and the sustained effectiveness of this intervention in the medium and long term.Trial registrationCurrent Controlled Trials ISRCTN03863885.

ROC Generated Thresholds for Field-Assessed Aerobic Fitness Related to Body Size and Cardiometabolic Risk in Schoolchildren

Objectives 1. to investigate whether 20 m multi-stage shuttle run performance (20mSRT), an indirect measure of aerobic fitness, could discriminate between healthy and overweight status in 9–10.9 yr old schoolchildren using Receiver Operating Characteristic (ROC) analysis; 2. Investigate if cardiometabolic risk differed by aerobic fitness group by applying the ROC cut point to a second, cross-sectional cohort. Design Analysis of cross-sectional data. Participants 16,619 9–10.9 year old participants from SportsLinx project and 300 11–13.9 year old participants from the Welsh Schools Health and Fitness Study. Outcome Measures SportsLinx; 20mSRT, body mass index (BMI), waist circumference, subscapular and superilliac skinfold thicknesses. Welsh Schools Health and Fitness Study; 20mSRT performance, waist circumference, and clustered cardiometabolic risk. Analyses Three ROC curve analyses were completed, each using 20mSRT performance with ROC curve 1 related to BMI, curve 2 was related to waist circumference and 3 was related to skinfolds (estimated % body fat). These were repeated for both girls and boys. The mean of the three aerobic fitness thresholds was retained for analysis. The thresholds were subsequently applied to clustered cardiometabolic risk data from the Welsh Schools study to assess whether risk differed by aerobic fitness group. Results The diagnostic accuracy of the ROC generated thresholds was higher than would be expected by chance (all models AUC >0.7). The mean thresholds were 33 and 25 shuttles for boys and girls respectively. Participants classified as ‘fit’ had significantly lower cardiometabolic risk scores in comparison to those classed as unfit (p<0.001). Conclusion The use of the ROC generated cut points by health professionals, teachers and coaches may provide the opportunity to apply population level ‘risk identification and stratification’ processes and plan for “at-risk” children to be referred onto intervention services.

Physical activity, cardiorespiratory fitness, and clustered cardiometabolic risk in 10- to 12-year-old school children: The REACH Y6 study

(1) Investigate whether clustered cardiometabolic risk score, cardiorespiratory fitness (CRF), sedentary time (ST), and body mass index Z‐scores (BMI Z‐scores), differed between participants that met and did not achieve ≥60 min of daily moderate to vigorous intensity physical activity (MVPA). (2) Compare clustered cardiometabolic risk score, BMI Z‐score, ST, and MVPA by CRF status.

Changes in fitness, body mass index and obesity in 9-10 year olds.

BACKGROUND The prevalence of obesity in children has increased substantially in recent years and, paediatric obesity and poor fitness are risk factors for disease. The present study aimed to assess changes in body mass index (BMI), the prevalence of obesity and changes in aerobic endurance over time in 9-10-year-old schoolchildren. METHODS Participants were recruited by the SportsLinx project from primary schools across Liverpool. Height and weight data were used to calculate BMI. The prevalence of obesity and overweight were estimated using age- and sex-specific cut-off points. Performance on the 20-m multi-stage shuttle runs test (20 mMST) was used as a marker of aerobic endurance. Data were available for 13,418 (6572 boys, 6846 girls) 9-10-year-old children. Analysis of covariance was completed to assess year-on-year changes in BMI controlling for deprivation (IMD) and 20 mMST performance, and 20 mMST performance controlling for IMD and BMI. RESULTS No significant changes in BMI from baseline were observed (P > 0.05). Obesity prevalence reduced in girls (2005 = 10.3%, 2008 = 8.52% in 2008). The data for boys showed no reductions in prevalence (2005 = 6.77%, 2008 = 7.87%). The most recent cohort for boys and two most recent cohorts for girls had lower levels of aerobic endurance than baseline (2004-2005) (P <or= 0.01). CONCLUSIONS The data suggest a plateau in the yearly increases in BMI in 9-10 year olds independent of deprivation and fitness and a declining prevalence of obesity in girls. Levels of aerobic endurance have declined independent of BMI and deprivation. The current obesity interventions in place appear to be having some impact on BMI, but further investment is urged to promote fitness in children.

Changes in Cardiorespiratory Fitness in 9- to 10.9-Year-Old Children: SportsLinx 1998-2010

PURPOSE The studys purposes were to 1) assess changes in cardiorespiratory fitness (CRF) from 1998 to 2010, controlling for decimal age and body mass index (BMI), and 2) repeat the analysis in cohorts from 2005 to 2010, controlling for maturation, deprivation, and BMI. METHODS A total of 27,942 (n = 14,247 boys) 9- to 10.9-yr-old participants from one UK city were included in this serial cross-sectional study from 1998-1999 to 2009-2010. An indices of multiple deprivation (IMD) score was assigned to each participant on the basis of home postcode. Stature, sitting stature, and body mass were estimated. BMI and somatic maturity were calculated. Performance on the 20-m multistage shuttle run test (20mSRT) was used to estimate CRF (total shuttles). One-way ANCOVAs were completed to assess temporal trends in CRF, separately by sex. Model 1 assessed changes from 1998 to 2010 and included decimal age and BMI as covariates. Model 2 assessed changes from 2005 to 2010 and included maturity, IMD, and BMI as covariates. RESULTS Results indicate that 20mSRT performance has declined in UK schoolchildren. An annual decline of 1.34% and 2.29% was observed in boys and girls, respectively. In model 1, for boys, the baseline cohort performed better than all other groups with the exception of the 1999-2000 group. For girls, declines in 20mSRT performance were observed from 2003 onward. In model 2, for boys, the 2007-2008 and 2008-2009 cohorts completed fewer 20mSRT shuttles than all other groups. For girls, the 2007-2008 and 2008-2009 cohorts also performed worse than all other years. CONCLUSIONS The decline in CRF suggests children in the more recent SportsLinx cohorts may be at an increased risk of cardiometabolic illness in comparison with earlier cohorts. The promotion of vigorous physical activity is urged to promote CRF in children.

Pet ownership, dog types and attachment to pets in 9--10 year old children in Liverpool, UK

BackgroundLittle is known about ethnic, cultural and socioeconomic differences in childhood ownership and attitudes to pets. The objective of this study was to describe the factors associated with living with different pet types, as well as factors that may influence the intensity of relationship or ‘attachment’ that children have to their pet. Data were collected using a survey of 1021 9–10 year old primary school children in a deprived area of the city of Liverpool, UK.ResultsDogs were the most common pet owned, most common ‘favourite’ pet, and species most attached to. Twenty-seven percent of dog-owning children (10% of all children surveyed) reported living with a ‘Bull Breed’ dog (which includes Pit Bulls and Staffordshire Bull Terriers), and the most popular dog breed owned was the Staffordshire Bull Terrier. Multivariable regression modelling identified a number of variables associated with ownership of different pets and the strength of attachment to the child’s favourite pet. Girls were more likely to own most pet types, but were no more or less attached to their favourite pet than boys. Children of white ethnicity were more likely to own dogs, rodents and ‘other’ pets but were no more or less attached to their pets than children of non-white ethnicity. Single and youngest children were no more or less likely to own pets than those with younger brothers and sisters, but they showed greater attachment to their pets. Children that owned dogs lived in more deprived areas than those without dogs, and deprivation increased with number of dogs owned. ‘Pit Bull or cross’ and ‘Bull Breed’ dogs were more likely to be found in more deprived areas than other dog types. Non-whites were also more likely to report owning a ‘Pit Bull or cross’ than Whites.ConclusionsGender, ethnicity and socioeconomic status were associated with pet ownership, and sibling status with level of attachment to the pet. These are important to consider when conducting research into the health benefits and risks of the common childhood phenomenon of growing up with pets.