Urban-rural contrasts in fitness, physical activity, and sedentary behaviour in adolescents.

Research considering physical activity (PA), physical inactivity and health outcomes among urban and rural youth has produced equivocal findings. This study examined PA, physical inactivity, sedentary behaviours and cardiorespiratory fitness (CRF) in adolescents from urban and rural communities in the Portuguese Midlands. The sample included 362 adolescents (165 males, 197 females) of 13-16 years of age. CRF was assessed by the PACER test. A GT1M accelerometer was used to record 5 consecutive days of PA and time spent sedentary. Analyses of covariance (chronological age as co-variate) were performed to test the effect of the area of residence on sedentary behaviour, PA and CRF. Urban youth of both sexes spent less time in sedentary activities than rural youth. Urban males were more active than rural peers at the weekend, whereas urban females were significantly less active than rural females on week days and across all days assessed. Rural youth of both sexes had higher levels of CRF than urban youth. Area of residence was related to aerobic fitness, PA and time spent in sedentary behaviours among Portuguese youth. Interventions seeking to enhance health and active lifestyles in Portuguese youth should consider the potential impact of socio-geographic factors.

Advancing science and policy through a coordinated international study of physical activity and built environments: IPEN adult methods.

BACKGROUND: National and international strategies to increase physical activity emphasize environmental and policy changes that can have widespread and long-lasting impact. Evidence from multiple countries using comparable methods is required to strengthen the evidence base for such initiatives. Because some environment and policy changes could have generalizable effects and others may depend on each country's context, only international studies using comparable methods can identify the relevant differences. METHODS: Currently 12 countries are participating in the International Physical Activity and the Environment Network (IPEN) study. The IPEN Adult study design involves recruiting adult participants from neighborhoods with wide variations in environmental walkability attributes and socioeconomic status (SES). RESULTS: Eleven of twelve countries are providing accelerometer data and 11 are providing GIS data. Current projections indicate that 14,119 participants will provide survey data on built environments and physical activity and 7145 are likely to provide objective data on both the independent and dependent variables. Though studies are highly comparable, some adaptations are required based on the local context. CONCLUSIONS: This study was designed to inform evidence-based international and country-specific physical activity policies and interventions to help prevent obesity and other chronic diseases that are high in developed countries and growing rapidly in developing countries.

Re-evaluation of accelerometer thresholds for MVPA at age 16 in subjects previously studied at age 12.

BACKGROUND: A study deriving a threshold for moderate- to vigorous-intensity physical activity (MVPA) in terms of accelerometer counts in 12-year-old children was repeated with a subset of the same children at 16 years. METHODS: Fifteen girls and thirty boys took part in 6 activities (lying, sitting, slow walking, walking, hopscotch and jogging) while wearing an Actigraph 7164 accelerometer and a Cosmed K4b2 portable metabolic unit. Random intercepts modeling was used to estimate cut points for MVPA (defined as 4 METs). RESULTS: Using a single model, the sex-specific thresholds derived for MVPA at 16 years were some way below the 3600 counts/minute used for both sexes at age 12, particularly for girls. However graphical examination suggested that a single model might be inadequate to describe both higher- and lower-intensity activities. Models using only lower-intensity activities close to the 4 METs threshold supported retention of the 3600 counts/minute cut point for both sexes. CONCLUSIONS: When restricting to lower-intensity activities only, these data do not provide sufficient evidence to change the previously established cut point of 3600 counts/minute to represent MVPA. However, further data and more sophisticated modeling techniques are required to confirm this decision.

A prospective study of sedentary behavior in a large cohort of youth.

PURPOSE: The study's purpose was to describe longitudinal patterns of objectively measured sedentary behavior from age 12 to 16. METHODS: Children participating in the Avon Longitudinal Study of Parents and Children wore accelerometers for 1 wk at ages 12, 14, and 16. Participants included boys (n = 2591) and girls (n = 2845) living in a single geographic location in the United Kingdom (Bristol). Total minutes per day spent in sedentary behavior and time spent in blocks of sedentary behavior lasting 10-19, 20-29, and ≥ 30 min are described. Growth curve models were used to determine the rate of change in sedentary behavior from age 12 to 16. RESULTS: At age 12, the boys and girls, on average, were sedentary for 418.0 ± 67.7 and 436.6 ± 64.0 min·d(-1), respectively, and sedentary behavior increased over time to 468.0 ± 74.3 and 495.6 ± 68.9 min·d(-1) at age 14 and to 510.4 ± 76.6 and 525.4 ± 67.4 min·d(-1) at age 16. Growth curve analyses found that total sedentary behavior increased at a rate of 19.5 ± 0.7 and 22.8 ± 0.7 min·d(-1)·yr for the boys and girls, respectively. The absolute mean increase in total sedentary behavior (+92.4 and +88.8 min·d(-1) for the boys and girls, respectively) closely matched the mean decrease in light physical activity (-82.2 and -82.9 min·d(-1) for the boys and girls, respectively) from age 12 to 16. Time spent in continuous sedentary behavior lasting ≥ 30 min increased by 121% from age 12 to 16. CONCLUSIONS: Sedentary behavior increased with age, at the expense of light physical activity. The increase in sedentary behavior lasting ≥ 30 min in duration contributed greatly to the increase in total sedentary behavior.

The association between the type, context, and levels of physical activity amongst adolescents.

BACKGROUND: Little is known about how the type and context of physical activity behaviors varies among adolescents with differing activity levels. The aim of this study was to assess differences in the type and context of physical activity behaviors in adolescents by level of objectively measured physical activity. METHODS: Cross-sectional analysis of 2728 adolescents (1299 males, 1429 females) participating in the Avon Longitudinal Study of Parents and Children (ALSPAC). The mean (SD) age was 13.8 (+0.1) years. Physical activity was measured using an Actigraph over 7 days. Adolescents were categorized into tertiles of activity (less, moderately, highly active) using counts/min and min/d of moderate-to-vigorous activity (MVPA). Activity type was reported using the Previous Day Physical Activity Recall (PDPAR). Differences in the type and context of activity by activity level were analyzed using Chi squared. RESULTS: Highly active boys reported more job, outside, and sports activities on school days (P < .05), and more sports activities on nonschool days (P < .05). Highly active girls reported more outside activities on school days (P < .05). CONCLUSIONS: Identifying the type and context of physical activity behaviors associated with more active adolescents, can help inform policy and physical activity interventions aimed at increasing activity levels in adolescents.

Agreement in activity energy expenditure assessed by accelerometer and self-report in adolescents: variation by sex, age, and weight status.

The agreement between self-reported and objective estimates of activity energy expenditure was evaluated in adolescents by age, sex, and weight status. Altogether, 403 participants (217 females, 186 males) aged 13-16 years completed a 3-day physical activity diary and wore a GT1M accelerometer on the same days. Partial correlations (controlling for body mass) were used to determine associations between estimated activity energy expenditure (kcal · min(-1)) from the diary and accelerometry. Differences in the magnitude of the correlations were examined using Fisher's r to z transformations. Bland-Altman procedures were used to determine concordance between the self-reported and objective estimates. Partial correlations between assessments of activity energy expenditure (kcal · min(-1)) did not differ significantly by age (13-14 years: r = 0.41; 15-16 years: r = 0.42) or weight status (normal weight: r = 0.42; overweight: r = 0.39). The magnitude of the association was significantly affected by sex (Δr = 0.11; P < 0.05). The agreement was significantly higher in males than in females. The relationship between activity energy expenditure assessed by the objective method and the 3-day diary was moderate (controlling for weight, correlations ranged between 0.33 and 0.44). However, the 3-day diary revealed less agreement in specific group analyses; it markedly underestimated activity energy expenditure in overweight/obese and older adolescents. The assessment of activity energy expenditure is complex and may require a combination of methods.

Physical activity and cardiovascular risk factors in children.

BACKGROUND: A number of recent systematic reviews have resulted in changes in international recommendations for children's participation in physical activity (PA) for health. The World Health Authority (WHO) has recently released new recommendations. The WHO still recommends 60 min of moderate to vigorous physical activity (MVPA), but also emphasises that these minutes should be on top of everyday physical activities. Everyday physical activities total around 30 min of MVPA in the quintile of the least active children, which means that the new recommendations constitute more activity in total compared with earlier recommendations. OBJECTIVE: To summarise evidence justifying new PA recommendation for cardiovascular health in children. METHODS: The results of recent systematic reviews are discussed and supplemented with relevant literature not included in these reviews. PubMed was searched for the years 2006-2011 for additional topics not sufficiently covered by the reviews. RESULTS: PA was associated with lower blood pressure and a healthier lipid blood profile in children. The association was stronger when a composite risk factor score was analysed, and the associations between physical fitness and cardiovascular disease (CVD) risk factors were even stronger. Muscle strength and endurance exercise each had an effect on blood lipids and insulin sensitivity even if the effect was smaller for muscle strength than for aerobic exercise. New evidence suggests possible effects of PA on C-reactive protein. CONCLUSION: There is accumulating evidence that PA can have beneficial effects on the risk factors of CVD in children. Public health policy to promote PA in children, especially the most sedentary children, may be a key element to prevent the onset of CVD later in the children's lives.

International children's accelerometry database (ICAD): design and methods.

BACKGROUND: Over the past decade, accelerometers have increased in popularity as an objective measure of physical activity in free-living individuals. Evidence suggests that objective measures, rather than subjective tools such as questionnaires, are more likely to detect associations between physical activity and health in children. To date, a number of studies of children and adolescents across diverse cultures around the globe have collected accelerometer measures of physical activity accompanied by a broad range of predictor variables and associated health outcomes. The International Children's Accelerometry Database (ICAD) project pooled and reduced raw accelerometer data using standardized methods to create comparable outcome variables across studies. Such data pooling has the potential to improve our knowledge regarding the strength of relationships between physical activity and health. This manuscript describes the contributing studies, outlines the standardized methods used to process the accelerometer data and provides the initial questions which will be addressed using this novel data repository. METHODS: Between September 2008 and May 2010 46,131 raw Actigraph data files and accompanying anthropometric, demographic and health data collected on children (aged 3-18 years) were obtained from 20 studies worldwide and data was reduced using standardized analytical methods. RESULTS: When using ≥ 8, ≥ 10 and ≥ 12 hrs of wear per day as a criterion, 96%, 93.5% and 86.2% of the males, respectively, and 96.3%, 93.7% and 86% of the females, respectively, had at least one valid day of data. CONCLUSIONS: Pooling raw accelerometer data and accompanying phenotypic data from a number of studies has the potential to: a) increase statistical power due to a large sample size, b) create a more heterogeneous and potentially more representative sample, c) standardize and optimize the analytical methods used in the generation of outcome variables, and d) provide a means to study the causes of inter-study variability in physical activity. Methodological challenges include inflated variability in accelerometry measurements and the wide variation in tools and methods used to collect non-accelerometer data.

Epidemiology of generalized joint laxity (hypermobility) in fourteen-year-old children from the UK: a population-based evaluation.

OBJECTIVE: Although diagnostic criteria for generalized ligamentous laxity (hypermobility) in children are widely used, their validity may be limited, due to the lack of robust descriptive epidemiologic data on this condition. The present study was undertaken to describe the point prevalence and pattern of hypermobility in 14-year-old children from a population-based cohort. METHODS: We performed a cross-sectional analysis using the Avon Longitudinal Study of Parents and Children, a large population-based birth cohort. Hypermobility among children in the cohort (mean age 13.8 years) was measured using the Beighton scoring system. Objective measures of physical activity were ascertained by accelerometry. Data on other variables, including puberty and socioeconomic status, were collected. Simple prevalence rates were calculated. Chi-square tests and logistic regression analyses were used to assess associations of specific variables with hypermobility. RESULTS: Among the 6,022 children evaluated, the prevalence of hypermobility (defined as a Beighton score of ≥4 [i.e., ≥4 joints affected]) in girls and boys age 13.8 years was 27.5% and 10.6%, respectively. Forty-five percent of girls and 29% of boys had hypermobile fingers. There was a suggestion of a positive association between hypermobility in girls and variables including physical activity, body mass index, and maternal education. No associations were seen in boys. CONCLUSION: We have shown that the prevalence of hypermobility in UK children is high, possibly suggesting that the Beighton score cutoff of ≥4 is too low or that this scoring is not appropriate for use in subjects whose musculoskeletal system is still developing. These results provide a platform to evaluate the relationships between the Beighton criteria and key clinical features (including pain), thereby testing the clinical validity of this scoring system in the pediatric population.

The risk of reduced physical activity in children with probable Developmental Coordination Disorder: a prospective longitudinal study.

The aim of the current study was to test the hypothesis that children with probable Developmental Coordination Disorder have an increased risk of reduced moderate to vigorous physical activity (MVPA), using data from a large population based study. Prospectively collected data from 4331 children (boys=2065, girls=2266) who had completed motor coordination testing at 7 years and accelerometry at 12 years were analysed from the Avon Longitudinal Study of Parents and Children (ALSPAC). Probable DCD (p-DCD) was defined, using criteria based on the DSM IV classification, as those children below the 15th centile of the ALSPAC Coordination Test at seven years who had a functional impairment in activities of daily living or handwriting, excluding children with a known neurological diagnosis or IQ<70. Secondary exposure variables consisted of subtests from the ALSPAC Coordination test (manual dexterity, ball skills and balance). Objective measurement of the average daily minutes of MVPA was recorded as ≥3600 counts per minute (cpm) using actigraph accelerometry. Boys with p-DCD were less physically active than boys without DCD (mean difference in MVPA 4.36 cpm, t=2.69; p=0.007). For boys, targeting skill (bean bag toss) was related to increased MVPA, after adjustment for confounding factors including neonatal, family and environmental factors as well as Body Mass Index at age seven and 12 years (ß=0.76, t=3.37, p<0.001, CI 0.32-1.20). There was no difference in level of MVPA in girls with and without p-DCD (mean difference 1.35 min, t=0.97, p=0.31), which may reflect the low levels of MVPA of girls in this cohort. Our findings suggest that the presence of movement difficulties, particularly poor targeting (bean bag toss/ball skills), at a young age is a potential risk factor for reduced MVPA in boys.

Correlates of aerobic fitness in urban and rural Portuguese adolescents.

BACKGROUND: Improving physical fitness is often an objective of programmes aimed at preventing obesity among youth. AIM: To evaluate the association between cardiorespiratory fitness (CRF) and area of residence controlling for several correlates in adolescents. SUBJECTS AND METHODS: CRF was assessed with the progressive aerobic cardiovascular endurance run (PACER) test in a cross-sectional sample of 362 Portuguese adolescents (165 males, 197 females) of 13-16 years of age. Youth were classified by area of residence as urban or rural. Gender, age, weight status, parental education, screen time (inactivity) and moderate-to-vigorous physical activity (MVPA) were statistically controlled. Logistic regression analysis was used. RESULTS: Adolescents of both sexes from rural settings were 76% more likely to be classified as aerobically fit compared to those from urban areas. The odds ratio for CRF in the final model was similar in boys (OR = 0.24, 95% CI 0.06-0.99, p < 0.05) and girls (OR = 0.24, 95% CI 0.07-0.76, p < 0.05). MVPA and weight status were important predictors of CRF in Portuguese adolescents of 13-16 years of age. Maternal education was an additional predictor in girls. CONCLUSION: CRF and rural/urban settings were significantly related in this sample of Portuguese adolescents of both sexes.

Physical activity during pregnancy in a prospective cohort of British women: results from the Avon longitudinal study of parents and children.

We sought to examine the levels, types, and changes of physical activity and their correlates among pregnant women. Data came from 9,889 pregnant women with due dates between April 1, 1991 and December 31, 1992 who were participants of the Avon Longitudinal Study of Parents and Children (ALSPAC) in Bristol, Avon, Southwest England. Self-reported physical activity during pregnancy was collected via questionnaires administered at 18 and 32 weeks of gestation. We found, at 18 weeks of gestation, the prevalence of engaging in physical activity that was sufficient to cause sweating for ≥ 3 h/week (referred to as strenuous physical activity) was 48.8%. This percentage was similar at 32 weeks of gestation. The most common physical activity during pregnancy reported by these women was brisk walking, followed by swimming and ante-natal exercise. In models that mutually adjusted for all characteristics examined, younger women, women in lower social classes, those not employed during pregnancy, married and parous women (compared to those not in each of these groups) were more likely to report engaging in strenuous physical activity. After becoming pregnant, about two out of three of these women reported reducing physical activity levels at 18 weeks of gestation. In mutually adjusted models, women who were younger, fit and well, parous, and women from lower social classes (compared to those not in each of these groups) were less likely to report reducing their physical activity. Our findings provide insights that are relevant to the design of future observational and intervention studies concerned with the effects of physical activity during pregnancy on health outcomes for mothers and offspring.

Use of accelerometer data in prediction equations for capturing implausible dietary intakes in adolescents.

BACKGROUND: Reporting errors have been quantified in epidemiologic studies by comparing reported intakes with predicted energy requirements (pERs). Several studies lacking measures of physical activity level (PAL) assigned low-active levels to obtain pERs. OBJECTIVE: We applied objective physical activity measures to current methods to quantify dietary reporting errors and compared associations with anthropometric and dietary variables among plausible and implausible reporters. DESIGN: This study included 2868 adolescents with an average age of 13 y. Three-day dietary records, accelerometers, and dual-energy X-ray absorptiometry were used to assess diet, activity, and body composition, respectively. Three variations of physical activity coefficients were used: 1) assigning low physical activity coefficients (PA(low)), 2) calculating PAL values (PA(PAL)), and 3) applying minutes of moderate-to-vigorous physical activity (PA(MVPA)). RESULTS: Of the total participants, 51.5%, 51.8%, and 37.1% of the PA(low), PA(PAL), and PA(MVPA) groups, respectively, were classified as underreporters, and 40.8%, 37.9%, and 42.4% of the respective groups were classified as plausible reporters. Underreporters had a higher body mass index, body fat, and waist circumference than did plausible reporters (P < 0.001 for all). Overreporters had a lower weight and body fat than did plausible reporters (P < 0.001 for all). Underreporters reported lower dairy and calcium intakes than did plausible reporters; the results were attenuated with adjustment for total energy. CONCLUSION: Accounting for objective physical activity measures to quantify reporting errors resulted in different and potentially more reasonable proportions of implausible reporters.

Associations between sex-typed behaviour at age 31/2 and levels and patterns of physical activity at age 12: the Avon Longitudinal Study of Parents and Children.

BACKGROUND: Differences in sex-typed behaviour, including physical activity, are already apparent among preschool children. PURPOSE: To examine the associations between early sex-typed behaviour and later physical activity. METHODS: Children from the Avon Longitudinal Study of Parents and Children were asked to wear an accelerometer for 7 days at age 12. Physical activity outcomes were counts per minute (counts/min) and minutes of moderate to vigorous physical activity (MVPA). Sex-typed behaviour was assessed using the Pre-School Activities Inventory (PSAI) at age 3(1/2). Multivariable regression was used to examine the association between PSAI and physical activity, separately for boys and girls. RESULTS: Accelerometer data were collected from 2593 boys and 2858 girls, mean (SD) age 11.8 (0.23) years. A one point higher PSAI score (mean (SD) 61.7 (8.7) and 37.0 (9.1) for boys and girls, respectively) was associated with a higher level of physical activity (counts/min) of 2.3 (95% CI 0.9 to 3.7) in boys and 0.7 (95% CI -0.1 to 1.4) in girls. This is equivalent to a higher counts/min of 56.7 (95% CI 23.1 to 90.3) and 16.6 (95% CI -2.4 to 35.5) for boys and girls, respectively, for a higher PSAI score equivalent to the difference between boys and girls (24.7). Results for MVPA were similar. CONCLUSIONS: Higher male-typical behaviour in early childhood is associated with higher physical activity in early adolescence, particularly in boys.

Advancing the future of physical activity guidelines in Canada: an independent expert panel interpretation of the evidence.

The Canadian Society for Exercise Physiology, in partnership with the Public Health Agency of Canada, has initiated a review of their physical activity guidelines to promote healthy active living for Canadian children, youth, adults and older adults; previous guidelines were released in 2002, 2002, 1998 and 1999 respectively. Several background papers from this project were published recently and provide foundation evidence upon which to base new guidelines. Furthermore, comprehensive systematic reviews were completed to ensure a rigorous evaluation of evidence informing the revision of physical activity guidelines for asymptomatic populations. The overall guideline development process is being guided and assessed by the AGREE II instrument. A meeting of experts was convened to present the evidence complied to inform the guideline revisions. An independent expert panel was assembled to review the background materials and systematic reviews; listen to the presentations and discussions at the expert meeting; ask for clarification; and produce the present paper representing their interpretation of the evidence including grading of the evidence and their identification of needs for future research. The paper includes also their recommendations for evidence-informed physical activity guidelines.

Physical activity in children: does how we define neighbourhood matter?

Physical activity levels in children are low and factors in the neighbourhood are believed to be influential. However, uncertainty remains about how best to define the neighbourhood. We therefore sought to study the role of area definition on neighbourhood variations in child physical activity using data collected at age 11 from the Avon Longitudinal Study of Parents and Children, UK. We found the effect of neighbourhood of residence on variations in PA was small, explaining under 3% of variance at best, and was not strongly dependent on the manner by which the neighbourhood was defined. Our results suggest that while characteristics of local environments may be important determinants of activity, the delineation of neighbourhoods based on shared social or physical characteristics may not best capture the local influences.

Prospective associations between objective measures of physical activity and fat mass in 12-14 year old children: the Avon Longitudinal Study of Parents and Children (ALSPAC).

OBJECTIVE: To investigate associations between physical activity at age 12 and subsequent adiposity at age 14. DESIGN: Prospective birth cohort study with data collected between 2003 and 2007. SETTING: Original recruitment in 1991-2 of 14,541 pregnant women living in the former County of Avon (United Kingdom). PARTICIPANTS: At age 12, 11,952 children were invited to attend the research clinic. Of these, 7159 attended, and 4150 (1964 boys, 2186 girls) provided sufficient data on exposure, outcome, and confounding variables. MAIN OUTCOME MEASURE: Fat mass at age 14, measured by dual emission x ray absorptiometry, associated with physical activity at age 12, measured by accelerometry. RESULTS: Prospective associations of fat mass at age 14 (outcome) with physical activity at age 12 (exposure) were strong for both total activity (accelerometer counts/min) and for daily amount of moderate-vigorous physical activity (min/day). An extra 15 minutes of moderate-vigorous physical activity per day at age 12 was associated with lower fat mass at age 14 in boys (by 11.9% (95% confidence interval 9.5% to 14.3%)) and girls (by 9.8% (6.7% to 12.8%)). The proportion of physical activity due to moderate-vigorous physical activity was between 20% and 30% in boys and girls at the two ages. CONCLUSIONS: Higher levels of physical activity, in particular activity of moderate to higher intensities, are prospectively associated with lower levels of fat mass in early adolescence. Interventions to raise levels of physical activity in children are likely to be important in the fight against obesity.

The contribution of active travel to children's physical activity levels: cross-sectional results from the ALSPAC study.

OBJECTIVE: To assess the association between active travel to school and physical activity (PA) in a large population-based sample of 11-year old children. METHOD: Cross-sectional analyses using data from the Avon Longitudinal Study of Parents and Children (Bristol, UK), collected in 2002-2004. The analyses include all children providing valid data on objectively measured PA (Actigraph accelerometer), and having parent-proxy reported data on travel mode (walk, cycle, public transport, car) and distance to school (N=4688). RESULTS: 43.5% of children regularly walked or cycled to school (i.e. on every or most days). Compared with car travelers, walking to school was associated with 5.98 (95%CI: 3.82-8.14) more minutes of moderate-to-vigorous PA (MVPA) on weekdays in those living 0.5-1 miles from school, and with 9.77 (95%CI: 7.47-12.06) more minutes in those living at 1-5 miles. This equates to 24.6 to 40.2% of the average daily minutes of MVPA. Only modest differences were observed in those living <0.5 mile from school. CONCLUSION: Children who regularly walk to school are more active during the week than those travelling by car, especially if the distance is >0.5 mile. Increasing participation in active travel might be a useful part of an overall strategy to increase population PA.

Sedentary behavior and obesity in a large cohort of children.

The purpose of this study was to examine the association between sedentary behavior and obesity among 12-year-old children, while adjusting for moderate-to-vigorous physical activity (MVPA) and other potential confounding variables. Cross-sectional analyses were carried out with data from 5,434 children who participated in the Avon Longitudinal Study of Parents and Children (ALSPAC). Fat mass was derived using dual-energy X-ray emission absorptiometry, and height and weight measurements were used to calculate BMI (kg/m(2)). The children wore an accelerometer for 7 days. The cut points for sedentary behavior and MVPA were or=3,600 counts per minute (cpm), respectively. Logistic regression analyses were performed to estimate odds ratios (ORs), adjusting for potential confounders of physical activity that included gender, social factors, early life factors, and maturation. The minimally adjusted association between sedentary behavior and obesity was positive, OR = 1.18 (1.08, 1.28). After adjusting for the series of potential confounders of physical activity the positive association remained, OR = 1.32 (1.14, 1.53). The crude association between 15 min of MVPA per day and obesity was negative, OR = 0.54 (0.48, 0.62). When 15 min of MVPA per day was additionally controlled for in the models, the positive associations between sedentary behavior and obesity were negated. Sedentary behavior was positively associated with obesity in the 12-year-old children, but this association was not independent of MVPA; low levels of MVPA among the sedentary children increased the odds of obesity. These findings support the importance of specifically engaging in MVPA during childhood to reduce the prevalence of obesity.