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

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

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- and weight-specific targets for intervention

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

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) for children. The present 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 age 7 and 9 years using accelerometry. Outcome and exposures were time in SB and PAs and concurrent body mass index (BMI) Z-score and fat index (FI). Results: Adiposity at baseline was positively associated with change in SB (β=0.975, for FI) and negatively associated with changes in moderate-to-vigorous PA (MVPA) (β=-0.285 for BMI Z-score, β=-0.607 for FI), vigorous PA (VPA) (β= -0.095 for FI) and total PA (β=-48.675 for FI), but not vice versa. The changes in SB, MVPA and total PA for children with overweight/obesity were significantly more adverse than those of healthy weight children. Conclusions: A high BMI Z-score or high body fatness at baseline was associated with lower MVPA and VPA 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

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 7y (n=502; measures taken between October 2006-December 2007), 9y (n=506; October 2008-September 2009), 12y (n=420; October 2011-September 2012) and 15y (n=306; September 2014-September 2015). Participants wore an ActiGraph GT1M and epochs were classified as MVPA when accelerometer counts were ≥574 counts/15s. Weight and height were measured using standardised 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. 1hr/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). Conclusion: 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

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

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 GT1 M accelerometers over 5–7 days 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 (1.70 minutes/year) and increased from 12-15 years (1.99 minutes/year) (all p < 0.05). In girls daily VPA decreased from 7-9 years (1.70 minutes/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

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 eight years of follow-up, from Northeast 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 sub-groups 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. 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 7-15 years. Conclusions: Future policy and research efforts to promote physical activity should begin well before adolescence, and should include both boys and girls

Birth weight and adolescent blood pressure measured at age 12 years in the Gateshead Millennium Study

Birth weight and early growth have been associated with later blood pressure. However, not all studies consistently find a significant reduction in blood pressure with an increase in birth weight. In addition, the relative importance of birth weight and of other lifestyle and environmental factors is often overlooked and the association is rarely studied in adolescents. We investigated early life predictors, including birth weight, of adolescent blood pressure in the Gateshead Millennium Study (GMS). The GMS is a cohort of 1029 individuals born in 1999-2000 in Gateshead in Northern England. Throughout infancy and early childhood, detailed information was collected including birth weight and measures of height and weight. Assessments of 491 returning participants at age 12 years included measures of body mass and blood pressure. Linear regression and path analysis were used to determine predictors and their relative importance on blood pressure. Birth weight was not directly associated with blood pressure at age 12. However, after adjustment for contemporaneous BMI, an inverse association of standardised birth weight on systolic blood pressure was significant. The relative importance of birth weight on later systolic blood pressure was smaller than other contemporaneous body measures (height and BMI). There was no independent association of birth weight on blood pressure seen in this adolescent population. Contemporaneous body measures have an important role to play. Lifestyle factors that influence body mass or size, such as diet and physical activity, is where interventions directed at early prevention of hypertension should be targeted