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Background: Sedentary time (ST) has been reported to have a range of negative health effects in adults, however, the evidence for such effects among children and adolescents is sparse. The primary aim of the study was to examine associations between changes in sedentary behavior (time and fragmentation) and changes in adiposity across childhood and adolescence. Methods: Participants were recruited as part of the Gateshead Millennium Study. Measures were taken at age 7 ( n =502), 9 ( n =506), 12 ( n =420) and 15 years ( n =306). Participants wore an ActiGraph GT1M and accelerometer epochs were ‘sedentary’ when recorded counts were ⩽25 counts per 15 s. ST was calculated and fragmentation (SF) was assessed by calculating the number of sedentary bouts per sedentary hour. Associations of changes in ST and SF with changes in adiposity (body mass index (BMI), and fat mass index (FMI)) were examined using bivariate linear spline models. Results: Increasing ST by 1% per year was associated with an increase in BMI of 0.08 kg m −2 per year (95% CI: 0.06–0.10; P <0.001) and FMI of 0.15 kg m −2 per year (0.11–0.19; P <0.001). Change in SF was associated with BMI and FMI ( P <0.001). An increase of 1 bout per sedentary hour per year (that is, sedentary time becoming more fragmented) was associated with an increase in BMI of 0.07 kg m −2 per year (0.06–0.09; P <0.001) and an increase in FMI of 0.14 kg m −2 per year (0.10–0.18; P <0.001) over the 8 years period. However, an increase in SF between 9–12 years was associated with a 0.09 kg m −2 per year decrease in BMI (−0.18–0.00; P =0.046) and 0.11 kg m −2 per year decrease in FMI (−0.22–0.00; P =0.049). Conclusions: Increased ST and increased SF from 7–15 years were associated with increased adiposity. This is the first study to show age-specific associations between change in objectively measured sedentary behavior and adiposity after adjustment of moderate-to-vigorous-intensity physical activity in children and adolescents. The study suggests that, targeting sedentary behavior for obesity prevention may be most effective during periods in which we see large increases in ST.

Abstract Background The influence of sedentary time and habitual physical activity on the bone health of middle aged adults is not well known. Methods Bone mineral density (BMD) and hip bone geometry were evaluated in 214 men (n = 92) and women (n = 112) aged 62.1 ± 0.5 years from the Newcastle Thousand Families Study birth cohort. Accelerometry was used to measure physical activity (PA) and sedentary time over 4 days. Regression models were adjusted for clinical risk factor covariates. Results Men were more sedentary than women (P < 0.05), and sedentary time was negatively associated with spine BMD in men, with 84 minutes more sedentary time corresponding to 0.268 g.cm−2 lower BMD (β = −0.268; P = 0.017). In men, light PA and steps/day were positively associated with bone geometry and BMD. Steps/day was positively associated with bone geometry and femur BMD in women, with a positive difference of 1415 steps/day corresponding to 0.232 g.cm−2 greater BMD (β = 0.232, P = 0.015). Conclusions Sedentary time was unfavourably associated with bone strength in men born in North East England at age 62 years. Higher volumes of light PA, and meeting the public health daily step recommendations (10 000 steps/day) was positively associated with bone health in both sexes.

Background: There is a plethora of cross-sectional work on maternal perceptions of child weight status showing that mothers typically do not classify their overweight child as being overweight according to commonly used clinical criteria. Awareness of overweight in their child is regarded as an important prerequisite for mothers to initiate appropriate action. The gap in the literature is determining whether, if mothers do classify their overweight child’s weight status correctly, this is associated with a positive outcome for the child’s body mass index (BMI) at a later stage. Objective: To explore longitudinal perceptions of child weight status from mothers of a contemporary population-based birth cohort (Gateshead Millennium Study) and relationships of these perceptions with future child weight gain. Methods: Data collected in the same cohort at 7, 12 and 15 years of age: mothers’ responses to two items concerning their child’s body size; child’s and mother’s BMI; pubertal maturation; demographic information. Results: Mothers’ perceptions of whether their child was overweight did not change markedly over time. Child BMI was the only significant predictor of mothers’ classification of overweight status, and it was only at the extreme end of the overweight range and in the obese range that mothers reliably described their child as overweight. Even when mothers did appropriately classify their child as overweight at an earlier stage, this was not related to relatively lower child BMI a few years later. Conclusions: Mothers tend to classify their child as overweight in only more extreme cases. It is an important finding that no beneficial impact was shown on later child BMI in overweight children whose mothers classified their child’s weight status as overweight at an earlier stage.

Objective: Public health surveillance of physical activity in children in the UK depends on a parent-reported physical activity questionnaire which has not been validated. We aimed to validate this questionnaire against measurement of physical activity using accelerometry in 6–7-year-old children. Methods: In 130 children aged 6–7 years (64 boys, 66 girls) we estimated habitual moderate–vigorous intensity physical activity (MVPA) using the Health Survey for England parent-report questionnaire for physical activity. For the same time period and the same children, we measured MVPA objectively using 7-day accelerometry with the Actigraph accelerometer. Results: The questionnaire over-estimated MVPA significantly (paired t test, p<0.01). Mean error (bias) when using the questionnaire was 122 min/day (95% CI 124 to 169). Mean time spent in MVPA was 146 min/day (95% CI 124 to 169) using the questionnaire and 24 min/day (95% CI 22 to 26) using the accelerometer. Rank order correlations between MVPA measured by accelerometer and estimated by the questionnaire were not statistically significant. Conclusions: Public health surveillance of physical activity should not rely on this questionnaire. Levels of habitual physical activity in children are likely to be substantially lower than those reported in UK health surveys.

The beverage data were sorted into six categories (soft drinks (non-diet carbonated), fruit juice, squash, diet soft drinks (carbonated and non-carbonated), milk and water). Associations between high beverage intake at 30 months and high intake at 7 and 15 years were tested using logistic regression, adjusting for potentially confounding factors (gender and a binary measure of socio-economic status (SES) assessed at recruitment in 1999(7)).The reference value for adjusted Odds Ratios (aOR) was low or no intake. The adjusted odds ratio for being a soft drink consumer at age 7 years was almost 3 times the reference value of a non-consumer at age 30 months, but when the analysis was stratified for SES this increased to almost 5 times the reference for those of higher SES (OR 4.87 95% CI 2.34–10.14 P < 0.001) compared to those of lower SES where the OR was not significant. 7 years 15 years Beverage intake at 30 months aOR 95% CI P-value aOR 95% CI P-value Soft Drinks Consumer 2.912 1.652,5.135 <0.001 1.778 0.848,3.726 0.128 Squash High Intake 1.443 0.754,2.759 0.268 1.613 0.768,3.384 0.206 Fruit Juice High Intake 3.624 1.958,6.708 <0.001 1.640 0.761,3.533 0.207 Dist Soft Drinks Consumer 4.520 2.289,8.926 <0.001 2.091 0.961,4.551 0.063 Water High Intake 2.954 1.610,5.420 <0.001 1.410 0.631,3.151 0.402 Milk High Intake 1.988 0.993,3.980 0.053 0.991 0.452,2.170 0.982 These data suggest that the family environment can protect toddlers and children from excessive exposure to sweetened beverages, but that by adolescence young people are more exposed to external influences. 1.

Objective: To examine the impact of two diets differing in fat content and of wheel-running exercise on body mass. Methods: A total of 32 female C57BL/6J mice were assigned to either a high-fat (HF, 41% of dietary energy as fat) or low-fat (LF, 11% of dietary energy as fat) diet (16 per diet, individually housed). Eight mice from each diet group were housed with running wheels. Non-running mice were housed in similar cages, without wheels. Total cage activity (including non-exercise physical activity +wheel running) and sleep time were also measured using an infra-red-sensing device. Oestrus stage of the wheel-running mice was assessed daily for 17 days. Results: After 8 weeks, HF mice were significantly heavier than LF mice (P=0.004), but there was no detectable difference in body fat mass. Wheel-running mice tended to have a lower body mass than non-running controls (P=0.056). Voluntary cage activity was greater in LF control mice than HF control mice, and in wheel-running mice compared with non-wheel-running mice. HF control mice slept more than LF control mice. Stage of oestrus was significantly correlated with running distance, with mice running farthest in the immediate preoestrus phase and least immediately after oestrus. Conclusion: This study shows that HF diets in female C57BL/6J mice may increase sleep time similar to the effect of daytime sleepiness observed in obese humans.

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 were 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 the age of 12. However, after adjustment for contemporaneous body mass index (BMI), an inverse association of standardized 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, where interventions are directed at early prevention of hypertension should be targeted.

Background and Aims The worldwide increase in the Metabolic Syndrome is associated with adverse health outcomes and significant healthcare costs. Early life exposures are key factors in determining later health. Children born preterm appear to be at higher risks of developing insulin resistance. We aimed to determine the prevalence of novel metabolic biomarkers in a cohort of teenage children who were born preterm (< =34 weeks gestation) and correlate these with physical activity. Methods We studied 24 children using standard techniques including auxology, body composition (BODPOD™), insulin resistance (fasting and post-glucose load) and daily activity (Actigraph™ and Actilife™ software). We measured 31-P and 1-H magnetic resonance spectroscopy (MRS) and assessed intra-hepatic lipid (IHL) content and phospho-creatine recovery after standardised exercise within the MR scanner. Results IHL was associated with increases in body mass and fat mass index (% body fat/height2). There was a weak association between glucose levels and muscle recovery time with increased IHL. Recovery from exercise was correlated with % time spent in daily moderate-to-vigorous physical activity (MVPA) and sedentary activity. Only 5 children achieved an activity time within 10% of the recommended 60 minutes or more of MVPA per day (mean:39 minutes). Conclusions Children born preterm have evidence of adverse metabolic outcomes in later life. IHL deposition is related to overall fatness, and may be significant in adverse metabolic processes. Measured physical activity correlates with the ability of muscle to recover from a defined exercise. Improving MVPA may result in health benefits.

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: r s  = 0.76, p  < 0.01; panel 2: r s  = 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.