Paul J. Collings

Objectively measured physical activity in four-year-old British children: a cross-sectional analysis of activity patterns segmented across the day

BackgroundLittle is known about preschool-aged children’s levels of physical activity (PA) over the course of the day. Using time-stamped data, we describe the levels and patterns of PA in a population-based sample of four-year-old British children.MethodsWithin the Southampton Women’s Survey the PA levels of 593 4-year-old children (51% female) were measured using (Actiheart) accelerometry for up to 7 days. Three outcome measures: minutes spent sedentary (<20xa0cpm); in light (LPA: ≥20 – 399xa0cpm) and in moderate-to-vigorous activity (MVPA: ≥400xa0cpm) were derived. Average daily activity levels were calculated and then segmented across the day (morning, afternoon and evening). MVPA was log-transformed. Two-level random intercept models were used to analyse associations between activity level and temporal and demographic factors.ResultsChildren were active for 67% (mean 568.5 SD 79.5 minutes) of their daily registered time on average, with 88% of active time spent in LPA. All children met current UK guidelines of 180 minutes of daily activity. There were no differences in children’s average daily levels of sedentary activity and LPA by temporal and demographic factors: differences did emerge when activity was segmented across the day. Sex differences were largest in the morning, with girls being more sedentary, spending fewer minutes in LPA and 18% less time in MVPA than boys. Children were more sedentary and less active (LPA and MVPA) in the morning if they attended childcare full-time compared to part-time, and on weekend mornings compared to weekdays. The reverse was true for weekend afternoons and evenings. Children with more educated mothers were less active in the evenings. Children were less sedentary and did more MVPA on summer evenings compared to winter evenings.ConclusionsPreschool-aged children meet current physical activity guidelines, but with the majority of their active time spent in LPA, investigation of the importance of activity intensity in younger children is needed. Activity levels over the day differed by demographic and temporal factors, highlighting the need to consider temporality in future interventions. Increasing girls’ morning activity and providing opportunities for daytime activity in winter months may be worthwhile.

Association between birth weight and objectively measured sedentary time is mediated by central adiposity: data in 10,793 youth from the International Children’s Accelerometry Database

Background: Birth weight is an early correlate of disease later in life, and animal studies suggest that low birth weight is associated with reduced activity and increased sedentary time. Whether birth weight predicts later sedentary time in humans is uncertain. Objectives: We examined the relation between birth weight and sedentary time in youth and examined whether this association was mediated by central adiposity. Design: We used pooled cross-sectional data from 8 observational studies conducted between 1997 and 2007 that consisted of 10,793 youth (boys: 47%) aged 6–18 y from the International Children’s Accelerometry Database. Birth weight was measured in hospitals or maternally reported, sedentary time was assessed by using accelerometry (<100 counts/min), and abdominal adiposity (waist circumference) was measured according to WHO procedures. A mediation analysis with bootstrapping was used to analyze data. Results: The mean (±SD) time spent sedentary was 370 ± 91 min/d. Birth weight was positively associated with sedentary time (B = 4.04, P = 0.006) and waist circumference (B = 1.59, P < 0.001), whereas waist circumference was positively associated with sedentary time (B = 0.82, P < 0.001). Results of the mediation analysis showed a significant indirect effect of birth weight on sedentary time through waist circumference (B: 1.30; 95% bias-corrected CI: 0.94, 1.72), and when waist circumference was controlled for, the effect of birth weight on sedentary time was attenuated by 32% (B = 2.74, P = 0.06). Conclusion: The association between birth weight and sedentary time appears partially mediated by central adiposity, suggesting that both birth weight and abdominal adiposity may be correlates of sedentary time in youth.

Physical Activity, Sedentary Time, and Fatness in a Biethnic Sample of Young Children.

Purpose This study aimed to investigate associations of objectively measured physical activity (PA) and sedentary time with adiposity in a predominantly biethnic (South Asian and White British) sample of young children. Methods The sample included 333 children age 11 months to 5 yr who provided 526 cross-sectional observations for PA and body composition. Total PA volume (vector magnitude counts per minute), daily time at multiple intensity levels (the cumulative time in activity >500, >1000, >1500, …, >6000 counts per minute), and time spent sedentary (<820 counts per minute), in light PA (820–3907 counts per minute) and in moderate-to-vigorous PA (≥3908 counts per minute) were estimated with triaxial accelerometry. Indicators of adiposity included body mass index, waist circumference, and the sum of subscapular and triceps skinfold thicknesses. Statistical analyses were performed using multilevel regression and isotemporal substitution models adjusted for confounders. Effect modification by ethnicity was examined. Results There was no evidence for effect modification by ethnicity (P interaction ≥ 0.13). In the whole sample, the accumulated time spent above 3500 counts per minute (i.e., high light-intensity PA) was inversely associated with the sum of skinfolds (&bgr; = −0.60 mm, 95% confidence interval [CI] = −1.19 to −0.021, per 20 min·d−1), and the magnitude of association increased dose dependently with PA intensity (peaking for time spent >6000 counts per minute = −1.57 mm, 95% CI = −3.01 to −0.12, per 20 min·d−1). The substitution of 20 min·d−1 of sedentary time with moderate-to-vigorous PA was associated with a lower sum of skinfolds (−0.77 mm, 95% CI = −1.46 to −0.084). Conclusions High light-intensity PA appears to be beneficial for body composition in young South Asian and White British children, but higher-intensity PA is more advantageous.

Biological Maturation, Central Adiposity, and Metabolic Risk in Adolescents: A Mediation Analysis

BACKGROUNDnEarlier biological maturation has been related to increased metabolic risk. In this study, we verified mediating effects by central adiposity of the relationship between somatic maturity and metabolic risk factors in adolescents.nnnMETHODSnIn a cross-sectional study, 1034 adolescents aged 10-16 years from Londrina/PR/Brazil were evaluated. The age of peak height velocity (PHV) method was used to evaluate somatic maturity. Central adiposity was estimated through waist circumference measurements. Fasting glucose, triglycerides, high-density lipoprotein cholesterol (HDL-C), and blood pressure were measured as metabolic risk indicators. Physical activity (Baecke questionnaire) and cardiorespiratory fitness (20-m shuttle run test) were used as covariates.nnnRESULTSnExcept for fasting glucose, waist circumference showed partial or full mediation of the relationship between maturity and the following metabolic risk factors with their respective z-score values: triglycerides (boysu2009=u2009-3.554 vs. girlsu2009=u2009-5.031), HDL-C (boysu2009=u2009+5.300 vs. girlsu2009=u2009+5.905), systolic blood pressure (boysu2009=u2009-3.540 vs. girlsu2009=u2009-3.763), diastolic blood pressure (boysu2009=u2009-2.967 vs. girlsu2009=u2009-3.264), and metabolic risk score (boysu2009=u2009-5.339 vs. girlsu2009=u2009-6.362).nnnCONCLUSIONSnThe results suggest that central obesity plays a mediating role in the relationship between somatic maturation and metabolic risk during adolescence.

Sleep Duration and Adiposity in Early Childhood: Evidence for Bidirectional Associations from the Born in Bradford Study

Study Objectives: To examine independent associations of sleep duration with total and abdominal adiposity, and the bidirectionality of these associations, in a young biethnic sample of children from a disadvantaged location. Methods: Child sleep duration (h/day) was parent‐reported by questionnaire and indices of total (body weight, body mass index, percent body fat (%BF), sum of skinfolds) and abdominal adiposity (waist circumference) were measured using standard anthropometric procedures at approximately 12, 18, 24, and 36 months of age in 1,338 children (58% South Asian; 42% White). Mixed effects models were used to quantify independent associations (expressed as standardised &bgr;‐coefficients (95% confidence interval (CI)) of sleep duration with adiposity indices using data from all four time‐points. Factors considered for adjustment in models included basic demographics, pregnancy and birth characteristics, and lifestyle behaviours. Results: With the exception of the sum of skinfolds, sleep duration was inversely and independently associated with indices of total and abdominal adiposity in South Asian children. For example, one standard deviation (SD) higher sleep duration was associated with reduced %BF by ‐0.029 (95% CI: −0.053, −0.0043) SDs. Higher adiposity was also independently associated with shorter sleep duration in South Asian children (for example, %BF: &bgr; = ‐0.10 (‐0.16, ‐0.028) SDs). There were no significant associations in White children. Conclusions: Associations between sleep duration and adiposity are bidirectional and independent among South Asian children from a disadvantaged location. The results highlight the importance of considering adiposity as both a determinant of decreased sleep and a potential consequence.

Cardiorespiratory fitness effect may be under-estimated in ‘fat but fit’ hypothesis studies

Abstract Background: Both cardiorespiratory fitness and body fat have been independently related to metabolic syndrome in adolescents; however, the strength of these relationships seems to be dependent on the outcome composition. Aim: To analyse the relationship between cardiorespiratory fitness and body fat combined with different indicators of metabolic risk in adolescents. Subjects and methods: The sample was composed of 957 adolescents (58.7% girls). Cardiorespiratory fitness was obtained using the 20-metre shuttle run test and skinfold thickness was collected for body fat estimation. Metabolic risk score was calculated from waist circumference, systolic and diastolic blood pressure, glucose, HDL cholesterol and triglycerides measurements and an alternative outcome without the central obesity indicator was adopted. Chronological age and somatic maturity were used as covariates. Results: Higher metabolic risk was observed in the highest fat/lowest fit adolescents (pu2009<u2009.05), regardless of sex and outcome. In the regression models, for full metabolic risk score, body fat presented higher coefficients compared to cardiorespiratory fitness in both sexes (boys: 0.501 vs −0.097; girls: 0.485 vs −0.087); however, in the metabolic risk without waist circumference, the coefficients became closer (boys: 0.290 vs −0.146; girls: 0.265 vs −0.120), with a concomitant decrease in body fat and increase in cardiorespiratory fitness coefficients. Conclusion: These findings suggest that body fat is strongly related to cardiovascular risk, but, when the outcome is calculated without the central obesity indicator, cardiorespiratory fitness becomes more related to metabolic risk.

Prevalence, trajectories, and determinants of television viewing time in an ethnically diverse sample of young children from the UK

BackgroundExcessive screen viewing in early childhood is associated with poor physical and psycho-social health and poor cognitive development. This study aimed to understand the prevalence, trajectory and determinants of television viewing time in early childhood to inform intervention development.MethodsIn this prospective longitudinal study, mothers of 1558 children (589 white British, 757 Pakistani heritage, 212 other ethnicities) completed questionnaires when their children were approximately 6, 12, 18, 24 and 36xa0months old. Mothers answered questions about their own and their child’s TV-time. TV-time trajectories were estimated by linear longitudinal multilevel modeling, potential determinants were considered in models.ResultsThe modelled trajectory estimated that 75% of children aged 12xa0months exceeded guidelines of zero screen-time. At 12xa0months of age an accelerated increase in TV-time was observed (<1xa0h/day at 14xa0months, >2xa0h/day by 30xa0months old). For every hour of mothers’ TV-time and every hour the TV was on in the home, children’s TV-time was 8xa0min and 1xa0min higher respectively at 6xa0months old (Pxa0<xa00.05), and 15xa0min and 3xa0min higher respectively at 36xa0months old (Pxa0<xa00.05). Children whose mothers did not agree that it was important their child did not watch too much TV, had 17xa0min more TV-time than their counterparts (Pxa0<xa00.05). Children of first time mothers had 6xa0min more TV-time (Pxa0<xa00.05). At 12xa0months of age, children of mothers experiencing stress watched 8xa0min more TV (Pxa0<xa00.05). By 36xa0months, children of Pakistani heritage mothers had 22xa0min more TV-time than those of white British mothers (Pxa0<xa00.05), and an additional 35xa0min of TV-time if their mother was not born in the UK (Pxa0<xa00.05).ConclusionsHigh levels of TV-time were prevalent. Intervention developers should consider targeting interventions before 12xa0months of age. Modifiable determinants included mothers’ own TV-time, the time the television is on in the home and mothers’ attitude towards child TV-time. These behaviours may be key components to address in interventions for parents. Mothers experiencing stress, first time mothers, and Pakistani heritage mothers (particularly those born outside of the UK), may be priority groups for intervention.

Reliability and validity of the early years physical activity questionnaire (EY-PAQ)

Measuring physical activity (PA) and sedentary time (ST) in young children (<5 years) is complex. Objective measures have high validity but require specialist expertise, are expensive, and can be burdensome for participants. A proxy-report instrument for young children that accurately measures PA and ST is needed. The aim of this study was to assess the reliability and validity of the Early Years Physical Activity Questionnaire (EY-PAQ). In a setting where English and Urdu are the predominant languages spoken by parents of young children, a sample of 196 parents and their young children (mean age 3.2 ± 0.8 years) from Bradford, UK took part in the study. A total of 156 (79.6%) questionnaires were completed in English and 40 (20.4%) were completed in transliterated Urdu. A total of 109 parents took part in the reliability aspect of the study, which involved completion of the EY-PAQ on two occasions (7.2 days apart; standard deviation (SD) = 1.1). All 196 participants took part in the validity aspect which involved comparison of EY-PAQ scores against accelerometry. Validty anaylsis used all data and data falling with specific MVPA and ST boundaries. Reliability was assessed using intra-class correlations (ICC) and validity by Bland–Altman plots and rank correlation coefficients. The test re-test reliability of the EY-PAQ was moderate for ST (ICC = 0.47) and fair for moderate-to-vigorous physical activity (MVPA)(ICC = 0.35). The EY-PAQ had poor agreement with accelerometer-determined ST (mean difference = −87.5 min·day−1) and good agreement for MVPA (mean difference = 7.1 min·day−1) limits of agreement were wide for all variables. The rank correlation coefficient was non-significant for ST (rho = 0.19) and significant for MVPA (rho = 0.30). The EY-PAQ has comparable validity and reliability to other PA self-report tools and is a promising population-based measure of young children’s habitual MVPA but not ST. In situations when objective methods are not possible for measurement of young children’s MVPA, the EY-PAQ may be a suitable alternative but only if boundaries are applied.

Physical activity maintenance and metabolic risk in adolescents

AimnExamine the association between child and adolescent physical activity maintenance categories and metabolic profile in adolescence.nnnMethodsnThis cross-sectional study was conducted with 1152 adolescents (57.4% female) aged 10-16 years from Londrina, Brazil. Physical activity was self-reported in childhood (7-10 years old, retrospective data) and adolescence through questionnaires. Cardiorespiratory fitness (20 m shuttle-run test), body fat (skinfolds), waist circumference, blood pressure (automatic instrument) and blood variables (fasting glucose, HDL-cholesterol and triglycerides) were measured at adolescence.nnnResultsnFrequency of physical activity in childhood and adolescence was 50.3 and 17.2%, respectively, and only 25.7% of boys and 10.9% of girls were active at both ages. Adolescents who were physically active in childhood alone were less likely [OR = 0.71 (95% CI: 0.52-0.97)] to present low cardiorespiratory fitness in adolescence compared to those who were non-active in childhood. Regardless of controlled, actives in childhood and adolescence were less likely to present low cardiorespiratory fitness [OR = 0.50 (95% CI: 0.34-0.73)], high blood pressure [OR = 0.52 (95% CI: 0.32-0.85)] and high metabolic risk score [OR = 0.44 (95% CI: 0.22-0.90)] compared to the non-actives at both ages.nnnConclusionsnActives through childhood to adolescence are less likely to present low cardiorespiratory fitness, high blood pressure and high metabolic risk.

Profiling Movement and Gait Quality Characteristics in Pre-School Children

ABSTRACT There is a dearth of suitable metrics capable of objectively quantifying motor competence. Further, objective movement quality characteristics during free play have not been investigated in pre-school children. The aims of this study were to characterize childrens free play physical activity and investigate how gait quality characteristics cluster with free play in pre-school children (3–5 years old). Sixty-one children (39 boys; 4.3 ± 0.7 years, 1.04 ± 0.05 m, 17.8 ± 3.2 kg) completed the movement assessment battery for children and took part in free play while wearing an ankle- and hip-mounted accelerometer. Characteristics of movement quality were profiled using a clustering algorithm. Spearmans rho and the Mann-Whitney U tests were used to assess relationships between movement quality characteristics and motor competence classification differences in integrated acceleration and spectral purity, respectively. Significant differences were found between motor competency classifications for spectral purity and integrated acceleration (p < .001). Spectral purity was hierarchically clustered with motor competence and integrated acceleration. Significant positive correlations were found between spectral purity, integrated acceleration and motor competence (p < .001). This is the first study to report spectral purity in pre-school children and the results suggest that the underlying frequency component of movement is clustered with motor competence.