Tracking of MVPA across childhood and adolescence.

OBJECTIVES: Tracking of physical activity from childhood onwards is an important public health issue, but evidence on tracking is limited. This study quantified the tracking of Moderate-Vigorous Physical Activity (MVPA) across childhood and adolescence in a recent cohort from England. DESIGN: Longitudinal, with a socio-economically representative sample from North-East England, over an 8-year period. METHODS: Measures of time spent in MVPA, with an Actigraph GT1M accelerometer, were made at age 7-8y (n = 622, T1), age 9-10y (n = 585, T2), age 12-13y (n = 525, T3) and age 14-16y (n = 361, T4). Tracking of MVPA was assessed using rank order correlations between time spent in MVPA T1-T2, T1-T3, and T1-T4, and by using Cohen's kappa to examine tracking of meeting the MVPA guideline (mean of 60 min/d). We examined whether tracking varied by sex, socio-economic status (SES), initial MVPA, or initial body fatness. RESULTS: Rank order correlations were all statistically significant at p < 0.01 and moderate: 0.58 between T1 and T2; 0.42 between T1 and T3; 0.41 between T1 and T4. Cohen's kappas for meeting the global MVPA guideline were all significant, weakening from moderate to low over the 8 years. Tracking was stronger in higher SES compared to lower SES groups, and there was some evidence that it was stronger in girls than boys, but the other explanatory variables had little influence on tracking. CONCLUSIONS: Tracking of MVPA from mid-childhood to mid-adolescence in this cohort was moderate. This study suggests there is a need to establish high MVPA by mid-childhood, and to mitigate the age-related reduction in MVPA which occurs from mid-childhood.

Early Years Physical Activity and Motor Skills Intervention-A Feasibility Study to Evaluate an Existing Training Programme for Early Years Educators.

A lack of fundamental motor skills (FMS) in the early years can lead to lower engagement with physical activity (PA), and track into adulthood. This study aimed to test the feasibility of an existing intervention for Early Years Educators ("Educators") designed to increase knowledge, confidence and the ability to increase PA and FMS of children in a deprived area of England. Non-randomised design with wait-list control. Sixty-seven settings in Middlesbrough, North East England were invited. Recruitment target: 10 settings, 2 Educators per setting, four children per Educator. INTERVENTION: one-day training course "Physical Literacy in the Early Years", an age-appropriate theoretical and practical training course to support the development of physical literacy. PRIMARY OUTCOMES: recruitment, retention, acceptability of intervention and outcome measures. SECONDARY OUTCOMES: change in Educators' knowledge, intentions and behaviour, and change in children's BMI z-score, PA and FMS. Eight settings were recruited; all Intervention Educators completed the training. Six settings participated at follow-up (four Intervention, two Control). The target for Educator recruitment was met (two per setting, total n = 16). Questionnaires were completed by 80% of Intervention Educators at baseline, 20% at follow-up. Control Educators completed zero questionnaires. No Educators took part in a process evaluation interview. Forty-eight children participated at baseline, 28 at follow-up. The intervention was deemed acceptable. The recruitment, retention and acceptability of measurements were insufficient to recommend proceeding. Additional qualitative work is needed to understand and surmount the challenges posed by the implementation of the trial.

Top 10 International Priorities for Physical Fitness Research and Surveillance Among Children and Adolescents: A Twin-Panel Delphi Study.

BACKGROUND: The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts. OBJECTIVE: This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents. METHODS: Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel. RESULTS: There was strong between-panel agreement (panel 1: rs = 0.76, p < 0.01; panel 2: rs = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) "conduct longitudinal studies to assess changes in fitness and associations with health". This was followed by (ii) "use fitness surveillance to inform decision making", and (iii) "implement regular and consistent international/national fitness surveys using common measures". CONCLUSIONS: The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

Changes in children's physical fitness, BMI and health-related quality of life after the first 2020 COVID-19 lockdown in England: A longitudinal study.

We aimed to assess one-year changes in physical fitness, health-related quality of life (HRQoL) and body mass index (BMI), encompassing the 2020 COVID-19 UK lockdowns. Data were collected (October 2019, November 2020) from 178 8-10-year-olds in Newcastle-upon-Tyne, England, 85% from England's most deprived quintile. Twenty-metre shuttle run test performance (20mSRT), handgrip strength (HGS), standing broad jump (SBJ), sit-and-reach, height, body mass, HRQoL (Kidscreen-27 questionnaire) and sports club participation were measured. BMI z-scores and overweight/obesity were calculated (≥85th centile). Paired t-tests and linear regression assessed change, adjusting for baseline BMI. Significant (p<0.001) changes were observed: increases in mean BMI (+1.5kg·m-2), overweight/obesity (33% to 47%), SBJ (+6.8cm) and HGS (+1.5kg); decreases in 20mSRT performance (-3 shuttles), sit-and-reach (-1.8cm). More children at follow-up were categorized "very low" for 20mSRT performance (35% baseline v 51%). Increased BMI z-score was associated with decreased "Physical Wellbeing" HRQoL. Follow-up sports club participation was associated with better 20mSRT performance (p=0.032), and "Autonomy & Parents" (p=0.011), "Social Support & Peers" (p=0.038) HRQoL. Children's 20mSRT performance and BMI changed adversely over one year; national lockdowns potentially made negative contributions. Physical fitness, physical activity and sports programmes should be part of children's physical and mental recovery from the pandemic.

Failure to Launch: Predictors of Unfavourable Physical Activity and Sedentary Behaviour Trajectories from Childhood to Adolescence: The Gateshead Millennium Study.

In a previous study based on this cohort, only 15% of the participants belonged to a favourable physical activity/sedentary behaviour trajectory group (characterised by relatively high moderate-vigorous intensity physical activity and relatively low sedentary behaviour across childhood and adolescence). Since this favourable trajectory is protective against obesity, we aimed to identify factors associated with membership of this group. In this longitudinal study, 671 participants were assessed at ages 7, 9, 12 and 15 years. Participants' demographics, socio-economic status (SES) and physical activity environment such as, sports club participation and commuting school were assessed at ages 7, 9 and 12 and analysed with favourable trajectory membership as an outcome using multinomial logistic regression. Sex (male) and SES (higher) were the non-modifiable factors associated with favourable trajectory group. Of the modifiable factors, commuting to school at age 7, a safe environment to play at age 7 and sports club participation at age 12 were all associated with more than 2.0 times increased probability of being in the most favourable trajectory. Future interventions to promote a favourable trajectory could focus on girls and participants with low SES. Promoting active commuting, safe local spaces to play and sports participation should also help lead to a favourable trajectory for physical activity and sedentary behaviour across childhood and adolescence.

Moderate-To-Vigorous Intensity Physical Activity and Sedentary Behaviour across Childhood and Adolescence, and Their Combined Relationship with Obesity Risk: A Multi-Trajectory Analysis.

The combined role of objectively assessed moderate-vigorous intensity physical activity (MVPA) and sedentary behaviour (SB) is unclear in obesity prevention. This study aimed to identify latent groups for MVPA and SB trajectories from childhood to adolescence and examine their relationship with obesity risk at adolescence. From the Gateshead Millennium Study, accelerometer-based trajectories of time spent in MVPA and SB at ages 7, 9, 12, and 15 were derived as assigned as the predictor variable. Fat mass index (FMI), using bioelectrical impedance at age 15, was the outcome variable. From 672 children recruited, we identified three distinct multiple trajectory groups for time spent in MVPA and SB. The group with majority membership (54% of the cohort) had high MVPA and low SB at childhood, but MVPA declined and SB increased by age 15. One third of the cohort (31%) belonged to the trajectory with low MVPA and high time spent sedentary throughout. The third trajectory group (15% of the cohort) that had relatively high MVPA and relatively low SB throughout had lower FMI (-1.7, 95% CI (-3.4 to -1.0) kg/m2, p = 0.034) at age 15 compared to the inactive throughout group. High MVPA and low SB trajectories when combined are protective against obesity.

The association between physical fitness, sports club participation and body mass index on health-related quality of life in primary school children from a socioeconomically deprived area of England.

We examined associations between physical fitness components, body mass index (BMI) and sports club participation on health-related quality of life (HRQoL) in 8- to 11-year-old children from a socioeconomically deprived region of England. From May-October 2019, 432 children completed the HRQoL questionnaire Kidscreen-27 and Leisure Time Physical Activity Survey, and a physical fitness testing battery of 20 m shuttle run test (20mSRT), handgrip strength (Handgrip), standing broad jump (Broad Jump), and sit-and-reach. Height, body mass, BMI and somatic maturity data were collected. Comparisons with reference populations were undertaken using a quintile framework. Linear and quantile regression assessed associations between physical fitness components and HRQoL variables. Using English Indices of Multiple Deprivation, 90% of children were from the most deprived quintile and 39% were overweight or obese. More children scored poorly on the Physical Wellbeing (40%) and Psychological Wellbeing (45%) HRQoL domains than the reference population (31%). Physical fitness scores were generally classed as 'low'-'very low' (42-58%). 20mSRT and Broad Jump performance explained an additional 10.7% of variance in Physical Wellbeing after adjusting for BMI z-score, sex and age (total R2 21.2%). Quantile regression identified a subset of children who rated Physical Wellbeing as high regardless of 20mSRT performance. Sports club participation was associated with better 20mSRT and Broad Jump performance, and all domains of HRQoL. Our data indicate that some physical fitness components and sports club participation are positively associated with HRQoL of children from socioeconomically deprived areas, irrespective of BMI z-score. Interventions to improve HRQoL should consider both aspects.

Variations in accelerometry measured physical activity and sedentary time across Europe - harmonized analyses of 47,497 children and adolescents.

BACKGROUND: Levels of physical activity and variation in physical activity and sedentary time by place and person in European children and adolescents are largely unknown. The objective of the study was to assess the variations in objectively measured physical activity and sedentary time in children and adolescents across Europe. METHODS: Six databases were systematically searched to identify pan-European and national data sets on physical activity and sedentary time assessed by the same accelerometer in children (2 to 9.9 years) and adolescents (≥10 to 18 years). We harmonized individual-level data by reprocessing hip-worn raw accelerometer data files from 30 different studies conducted between 1997 and 2014, representing 47,497 individuals (2-18 years) from 18 different European countries. RESULTS: Overall, a maximum of 29% (95% CI: 25, 33) of children and 29% (95% CI: 25, 32) of adolescents were categorized as sufficiently physically active. We observed substantial country- and region-specific differences in physical activity and sedentary time, with lower physical activity levels and prevalence estimates in Southern European countries. Boys were more active and less sedentary in all age-categories. The onset of age-related lowering or leveling-off of physical activity and increase in sedentary time seems to become apparent at around 6 to 7 years of age. CONCLUSIONS: Two third of European children and adolescents are not sufficiently active. Our findings suggest substantial gender-, country- and region-specific differences in physical activity. These results should encourage policymakers, governments, and local and national stakeholders to take action to facilitate an increase in the physical activity levels of young people across Europe.

A Preliminary Study of Physical Fitness in 8- to 10-Year-Old Primary School Children From North East England in Comparison With National and International Data.

Purpose: Despite recent updates to international normative values for physical fitness in young people, contemporary data sets from England are sparse with no published data available from the North East. We compared physical fitness in children from one primary school in North East England to International and European reference data, and other English regions. Methods: Eighty participants (mean age [SD]: 9.1 [0.6] y) completed a testing battery of 20-m shuttle run test, handgrip strength, standing broad jump, and sit-and-reach. Scores for each component were assessed against International or European age- and sex-specific centiles, then grouped into quintiles. Differences between our sample and European and English data sets were explored using z scores and t tests. Results: For all components, ≥58% of participants were classified as having "moderate" or lower levels. Twenty-meter shuttle run test performance was not substantially different compared with other English data sets. For handgrip and sit-and-reach, our sample scored significantly worse than South East children. Standing broad jump distance in girls, and handgrip in boys and girls, was significantly lower than North West equivalents. Conclusion: Physical fitness levels in primary school children from North East England are suboptimal, highlighting a need for large-scale monitoring studies to build on our preliminary findings.

Longitudinal changes in vigorous intensity physical activity from childhood to adolescence: Gateshead Millennium Study.

OBJECTIVE: The aims of our study were to quantify levels and investigate sex-specific changes and trajectories in VPA longitudinally from age 7 to 15 years. DESIGN: Longitudinal observational study. METHODS: Participants were part of the Gateshead Millennium Study. Measures were taken at age 7 (n=507), 9 (n=510), 12 (n=425) and 15 years (n=310). Vigorous physical activity was quantified objectively using ActiGraph GT1M accelerometers over 5-7days at the four time-points. Multilevel linear spline random-effects model and trajectory analysis to identify sub-groups were performed. RESULTS: In boys, average VPA declined across childhood followed by an increase at adolescence, while in girls, average VPA declined across the 8-year study period. In boys, daily VPA decreased from 9-12 years (1.70minutes/year) and increased from 12-15 years (1.99minutes/year) (all p <0.05). In girls daily VPA decreased from 7-9 years (1.70minutes/year) (p <0.05). Three VPA trajectories were identified which differed between the sexes. In boys, one group decreased from an initial relatively high level, one group, initially relatively low, increased, whereas the third one was stable over the 8-year period. In girls, all three groups declined from baseline. CONCLUSIONS: Marked sex and age-specific trajectories in VPA change were observed. These novel findings should help sports and exercise medicine specialists, as well as policy makers, in their effort to maintain or increase VPA in childhood and adolescence.

Non-linear longitudinal associations between moderate-to-vigorous physical activity and adiposity across the adiposity distribution during childhood and adolescence: Gateshead Millennium Study.

OBJECTIVE: Insufficient moderate-to-vigorous intensity physical activity (MVPA) is harmful for youth; however, the evidence for differential effects by weight status is limited. The study aimed to examine associations between MVPA and adiposity by weight status across childhood and adolescence. METHODS: Participants were from the Gateshead Millennium Study. Physical activity and body composition measures were taken at age 7 y (n = 502; measures taken between October 2006 and December 2007), 9 y (n = 506; October 2008-September 2009), 12 y (n = 420; October 2011-September 2012), and 15 y (n = 306; September 2014-September 2015). Participants wore an ActiGraph GT1M and epochs were classified as MVPA when accelerometer counts were ≥574 counts/15 s. Weight and height were measured using standardized methods and fat mass using bioelectrical impedance. Associations between MVPA and changes in BMI and FMI were examined by weight status using quantile regression. RESULTS: Higher MVPA was associated with lower FMI for the 25th, 50th, 75th, and 90th percentile and lower BMI at the 50th, 75th, and 90th percentile, independent of accelerometer wear time, sex, and sedentary time. The association between MVPA and change in adiposity was stronger in the higher than lower FMI and BMI percentiles (e.g., 1 h/day more MVPA was associated with a 1.5 kg/m2 and 2.7 kg/m2 lower FMI at the 50th and 90th FMI percentiles, respectively). CONCLUSIONS: The effect of MVPA on adiposity in the higher adiposity percentiles is stronger than reported to date. Given overweight and obese children are the highest risk group for later obesity, targeting MVPA might be a particularly effective obesity prevention strategy.

Bidirectional Associations Between Adiposity, Sedentary Behavior, and Physical Activity: A Longitudinal Study in Children.

BACKGROUND: Previous studies have reported on the associations between obesity and sedentary behavior (SB) or physical activity (PA) in children. This study examined longitudinal and bidirectional associations between adiposity and SB and PA in children. METHODS: Participants were 356 children in England. PA was measured at 7 and 9 years of age using accelerometry. Outcome and exposures were time in SB and PAs and concurrent body mass index z score and fat index (FI). RESULTS: Adiposity at baseline was positively associated with changes in SB (ß = 0.975 for FI) and negatively associated with changes in moderate to vigorous PA (ß = -0.285 for body mass index z score, ß = -0.607 for FI), vigorous PA (ß = -0.095 for FI), and total PA (ß = -48.675 for FI), but not vice versa. The changes in SB, moderate to vigorous PA, and total PA for children with overweight/obesity were significantly more adverse than those for children with healthy weight. CONCLUSIONS: A high body mass index z score or high body fatness at baseline was associated with lower moderate to vigorous PA and vigorous PA after 2 years, but not vice versa, which suggests that in this cohort adiposity influenced PA and SB, but the associations between adiposity and SB or PA were not bidirectional.

Timing of the decline in physical activity in childhood and adolescence: Gateshead Millennium Cohort Study.

BACKGROUND AND AIM: There is a widely held and influential view that physical activity begins to decline at adolescence. This study aimed to identify the timing of changes in physical activity during childhood and adolescence. METHODS: Longitudinal cohort study (Gateshead Millennium Study) with 8 years of follow-up, from North-East England. Cohort members comprise a socioeconomically representative sample studied at ages 7, 9, 12 and 15 years; 545 individuals provided physical activity data at two or more time points. Habitual total volume of physical activity and moderate-to-vigorous intensity physical activity (MVPA) were quantified objectively using the Actigraph accelerometer over 5-7 days at the four time points. Linear mixed models identified the timing of changes in physical activity across the 8-year period, and trajectory analysis was used to identify subgroups with distinct patterns of age-related changes. RESULTS: Four trajectories of change in total volume of physical activity were identified representing 100% of all participants: all trajectories declined from age 7 years. There was no evidence that physical activity decline began at adolescence, or that adolescent declines in physical activity were substantially greater than the declines during childhood, or greater in girls than boys. One group (19% of boys) had relatively high MVPA which remained stable between ages 7 and15 years. CONCLUSIONS: Future policy and research efforts to promote physical activity should begin well before adolescence, and should include both boys and girls.

Risk factors for eating disorder symptoms at 12 years of age: A 6-year longitudinal cohort study.

Eating disorders pose risks to health and wellbeing in young adolescents, but prospective studies of risk factors are scarce and this has impeded prevention efforts. This longitudinal study aimed to examine risk factors for eating disorder symptoms in a population-based birth cohort of young adolescents at 12 years. Participants from the Gateshead Millennium Study birth cohort (n = 516; 262 girls and 254 boys) completed self-report questionnaire measures of eating disorder symptoms and putative risk factors at age 7 years, 9 years and 12 years, including dietary restraint, depressive symptoms and body dissatisfaction. Body mass index (BMI) was also measured at each age. Within-time correlates of eating disorder symptoms at 12 years of age were greater body dissatisfaction for both sexes and, for girls only, higher depressive symptoms. For both sexes, higher eating disorder symptoms at 9 years old significantly predicted higher eating disorder symptoms at 12 years old. Dietary restraint at 7 years old predicted boys' eating disorder symptoms at age 12, but not girls'. Factors that did not predict eating disorder symptoms at 12 years of age were BMI (any age), girls' dietary restraint at 7 years and body dissatisfaction at 7 and 9 years of age for both sexes. In this population-based study, different patterns of predictors and correlates of eating disorder symptoms were found for girls and boys. Body dissatisfaction, a purported risk factor for eating disorder symptoms in young adolescents, developed concurrently with eating disorder symptoms rather than preceding them. However, restraint at age 7 and eating disorder symptoms at age 9 years did predict 12-year eating disorder symptoms. Overall, our findings suggest that efforts to prevent disordered eating might beneficially focus on preadolescent populations.

Can't play, won't play: longitudinal changes in perceived barriers to participation in sports clubs across the child-adolescent transition.

BACKGROUND: Participation in sports is associated with numerous physical and psychosocial health benefits, however, participation declines with age, and knowledge of perceived barriers to participation in children is lacking. This longitudinal study of children and adolescents aimed to use the ecological model of physical activity to assess changes in barriers to participation in sports clubs to identify age-specific and weight-specific targets for intervention. METHODS: Longitudinal study-Perceived barriers to sports participation were collected from a birth cohort, the Gateshead Millennium Study (n>500) at ages 9 and 12 years. The open-ended question 'Do you find it hard to take part in sports clubs for any reason?' was completed with free text and analysed using content analysis, and the social-ecological model of physical activity. RESULTS: Barriers from across the social-ecological model were reported. Barriers at 9 years were predominantly of a physical environmental nature, and required high parental involvement (for transport, money, permission), or were associated with a lack of suitable clubs. At 12 years, perceived barriers were predominantly classed as intrapersonal ('they're boring') or social environmental ('my friends don't go'). Perceived barriers were not associated with weight status. CONCLUSIONS: Perceived barriers to sports participation change rapidly in childhood and adolescence. Future interventions aiming to increase sports participation in children and adolescents should target specific age groups, should consider the rapid changes which occur in adolescence, and aim to address prominent barriers from across the socioecological model. Perceived barriers may be unrelated to current weight status, allowing for more inclusive solutions.

Development of sedentary behavior across childhood and adolescence: longitudinal analysis of the Gateshead Millennium Study.

BACKGROUND: In many parts of the world policy and research interventions to modify sedentary behavior of children and adolescents are now being developed. However, the evidence to inform these interventions (e.g. how sedentary behavior changes across childhood and adolescence) is limited. This study aimed to assess longitudinal changes in sedentary behavior, and examine the degree of tracking of sedentary behavior from age 7y to 15y. METHODS: Participants were part of the Gateshead Millennium Study cohort. Measures were made at age 7y (n = 507), 9y (n = 510), 12y (n = 425) and 15y (n = 310). Participants were asked to wear an ActiGraph GT1M and accelerometer epochs were defined as sedentary when recorded counts were ≤25 counts/15 s. Differences in sedentary time and sedentary fragmentation were examined using the Friedman test. Tracking was examined using Spearman's correlation coefficients and trajectories over time were assessed using multilevel linear spline modelling. RESULTS: Median daily sedentary time increased from 51.3% of waking hours at 7y to 74.2% at 15y. Sedentary fragmentation decreased from 7y to 15y. The median number of breaks/hour decreased from 8.6 to 4.1 breaks/hour and the median bout duration at 50% of the cumulative sedentary time increased from 2.4 min to 6.4 min from 7y to 15y. Tracking of sedentary time and sedentary fragmentation was moderate from 7y to 15y however, the rate of change differed with the steepest increases/decreases seen between 9y and 12y. CONCLUSION: In this study, sedentary time was high and increased to almost 75% of waking hours at 15y. Sedentary behavior became substantially less fragmented as children grew older. The largest changes in sedentary time and sedentary fragmentation occurred between 9y to 12y, a period which spans the transition to secondary school. These results can be used to inform future interventions aiming to change sedentary behavior.

Influence of adiposity on health-related quality of life in the Gateshead Millennium Study cohort: longitudinal study at 12 years.

OBJECTIVE: To examine whether adiposity is associated with an impaired quality of life (an individual's perception of their life) in general population samples in early adolescence. DESIGN AND METHODS: Relationships between a direct measure of adiposity (fat mass index from bioimpedance) and a proxy measure (waist circumference), and a generic (KIDSCREEN-27) and a weight-specific measure of health-related quality of life (HRQoL, Impact of Weight on Quality of Life-Kids (IWQOL-Kids)) were examined in a longitudinal population-based cohort of young adolescents aged 12 years (n=519). The effects of change in adiposity over time (from 7 years and 9 years) were also examined (n=331-445 in longitudinal analyses). RESULTS: Impairment in HRQoL was associated with current adiposity but it was not predicted by earlier adiposity. At 12 years, higher adiposity was associated with lower Physical Well-Being on KIDSCREEN-27, and with lower Total Scores on the weight-specific IWQOL-Kids instrument, the latter particularly in girls. CONCLUSIONS: Health and education professionals need to be aware in their clinical practice that higher adiposity impairs HRQoL in general populations of young adolescents. Further research would be useful to determine whether or not children of primary school age self-reporting lower HRQoL are more likely to develop higher adiposity later in adolescence or early adulthood.

Objective measurement of sedentary behavior: impact of non-wear time rules on changes in sedentary time.

BACKGROUND: Accelerometry non-wear time rules might affect sedentary time, and the associations with health outcomes such as adiposity. However, the exact effect of different non-wear time rules on sedentary time and reported changes in sedentary time is unknown. This study evaluated the effect of different accelerometry non-wear time rules on sedentary time and changes in sedentary time from age 9-12 years. METHODS: Accelerometry data were collected as part of the Gateshead Millennium Birth Cohort study. Participants were 9.3 (± 0.4) years at baseline (n = 17) and 12.5 (± 0.3) years at follow-up (n = 440). Sedentary time was defined using an accelerometry cut-point of 25 counts per 15 s. Non-wear time was defined using manual data reduction (the reference method) and 10 min, 20 min and 60 min consecutive zeros. Differences between methods were analyzed using repeated measures ANOVA with Bonferroni post-hoc analyses. RESULTS: Mean daily sedentary time at age 9 ranged from 364 min per day to 426 min using the 10 min and 60 min rule, respectively (p < 0.05). At 12 years, mean daily sedentary times ranged from 424 min to 518 min (p < 0.05). Mean changes in daily sedentary time over the three years ranged from 60 min to 93 min using the 10 min and 60 min rule, respectively (p < 0.05). When adjusting for wear time, differences in average sedentary time between methods decreased from 62 min to 27 min (age 9), 95 min to 32 min (age 12) and 33 min to 10 min (changes between 9 to 12 years). CONCLUSIONS: Using different non-wear time rules results in significant differences in daily sedentary time and changes in sedentary time. Correcting for wear time appears to be a reasonable approach to limiting these differences and may improve comparability between future studies. Using the 20 min rule, while correcting for wear time, provided the most accurate estimates of sedentary time and changes in sedentary time, compared to the manual reference in 9-12 year-olds.

Longitudinal associations between sports participation, body composition and physical activity from childhood to adolescence.

OBJECTIVES: Several important research questions have been addressed: (1) What are the cross-sectional associations between sports club participation, objectively measured physical activity, and adiposity? (2) Do measures of physical activity and adiposity predict subsequent sports club participation? (3) Does sports club participation predict subsequent measures of physical activity and adiposity? and (4) Do changes in sports club participation predict changes in objective measures of physical activity and adiposity? DESIGN: Longitudinal and cross-sectional. METHODS: Data from the Gateshead Millennium Study birth cohort (n=609 at age 7 years) were analysed for associations between adiposity, sports club participation and accelerometer-measured physical activity from ages 7y to 9y to 12y. RESULTS: Seventy-two per cent of 9 year olds and 63% of 12 year olds took part in a sports club. Sports club participation was significantly associated with overall accelerometer-measured physical activity at 12y (coefficient=0.0.09; 95% CI: 0.01-0.16) but not 9y. An inverse relationship between fat mass (estimated from bioelectric impedance) and sport club participation, and between fat mass and accelerometer-measured physical activity was observed at 12y, but not 9y. Sports club participation at 9y was highly predictive of participation at 12y. Sports club participation was significantly associated with socioeconomic status; fewer children from poorer areas took part. CONCLUSIONS: Sports club participation in adolescence may be associated with decreased levels of adiposity. Furthermore, the potential benefits of sports club participation for adiposity are likely generated from continuous participation in sports, rather than any long-term protective effects.

Physical activity, diet and BMI in children aged 6-8 years: a cross-sectional analysis.

OBJECTIVE: To assess relationships between current physical activity (PA), dietary intake and body mass index (BMI) in English children. DESIGN AND SETTING: Longitudinal birth cohort study in northeast England, cross-sectional analysis. PARTICIPANTS: 425 children (41% of the original cohort) aged 6-8 years (49% boys). MAIN OUTCOME MEASURES: PA over 7 days was measured objectively by an accelerometer; three categories of PA were created: 'active' ≥60 min/day moderate-to-vigorous-intensity PA (MVPA); 'moderately active' 30-59 min/day MVPA; 'inactive' <30 min/day MVPA. Dietary intake over 4 days was measured using a prospective dietary assessment tool which incorporated elements of the food diary and food frequency methods. Three diet categories were created: 'healthy', 'unhealthy' and 'mixed', according to the number of portions of different foods consumed. Adherence to the '5-a-day' recommendations for portions of fruit and vegetables was also assessed. Children were classified as 'healthy weight' or 'overweight or obese' (OW/OB) according to International Obesity Taskforce cutpoints for BMI. Associations between weight status and PA/diet categories were analysed using logistic regression. RESULTS: Few children met the UK-recommended guidelines for either MVPA or fruit and vegetable intake, with just 7% meeting the recommended amount of MVPA of 60 min/day, and 3% meeting the 5-a-day fruit and vegetable recommendation. Higher PA was associated with a lower OR for OW/OB in boys only (0.20, 95% CI 0.04 to 0.88). There was no association detected between dietary intake and OW/OB in either sex. CONCLUSIONS: Increasing MVPA may help to reduce OW/OB in boys; however, more research is required to examine this relationship in girls. Children are not meeting the UK guidelines for diet and PA, and more needs to be done to improve this situation.