Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults Predictive Validity and Classification Accuracy of ActiGraph Energy Expenditure Equations and Cut-Points in Young Children One-year changes in physical activity and sedentary behavior among adolescents: the Croatian Physical Activity in Adolescence Longitudinal Study (CRO-PALS). Psychosocial correlates of physical activity and sedentary leisure habits in young adolescents: the Teens Eating for Energy and Nutrition at School study. Trends in physical activity and sedentary behaviour in adolescence: ethnic and socioeconomic differences Behavioral engineering of activity choice in obese children Research priorities for child and adolescent physical activity and sedentary behaviours: an international perspective using a twin-panel Delphi procedure Correlates of preschool children’s objectively measured physical activity and sedentary behavior: a cross-sectional analysis of the SPLASHY study Associations Between Screen-Based Sedentary Behavior and Cardiovascular Disease Risk Factors in Korean Youth A cluster-randomized controlled trial to reduce sedentary behavior and promote physical activity and health of 8-9 year olds: The Transform-Us! Study A School-Based, Peer-Led, Social Marketing Intervention To Engage Spanish Adolescents in a Healthy Lifestyle ("We Are Cool"-Som la Pera Study): A Parallel-Cluster Randomized Controlled Study. Longitudinal sedentary behavior changes in adolescents in Ho Chi Minh City. Psychosocial correlates of physical activity in healthy children. Time spent in sedentary behavior and changes in childhood BMI: a longitudinal study from ages 9 to 15 years Intervening to Reduce Sedentary Behaviors and Childhood Obesity among School-Age Youth: A Systematic Review of Randomized Trials Decreasing sedentary behaviors in treating pediatric obesity. The relationship between physical activity, sedentary behaviour and psychological wellbeing among adolescents
Adults are sedentary for an alarming 9 to 10 hours per day ( 1 ) . Accordingly , the popular press has coined the phrase sitting is the new smoking to describe a current epidemic of developed nations ( 24 ) . Evidence indicates that sedentary time is associated with incident cardiovascular disease , incidence of cardiovascular diseaserelated risk factors , and mortality ( 5 , 6 ) . Of note , the risk conferred by prolonged sedentariness is eliminated only by high levels of moderate- to vigorous-intensity physical activity ( MVPA ) ( about 60 to 75 min/d ) , which exceed physical activity recommendations ( 7 , 8) . As such , sedentary behavior is now believed to represent a clinical ly important aspect of a person 's physical activity profile and is no longer considered simply the extreme low end of the physical activity continuum ( 5 ) . Studies linking sedentary behavior to health outcomes have relied almost exclusively on self-reported  sedentary time  , which is subject to reporting bias and measurement error ( 9 ) . A 2015 systematic review ( 5 ) identified only 1 study ( NHANES [ National Health and Nutrition Examination Survey ] ) that examined the association between objective ly measured sedentary time and health outcomes , a study limited by a small event rate ( 10 ) . New studies using NHANES data have since been published , with longer follow-up and higher event rates ( 1115 ) . However , some of these studies have reported an association between objective ly measured sedentary time and mortality ( 11 , 14 , 15 ) , but others have not ( 12 , 13 ) . Additional cohort studies are thus needed to rectify evidence gaps . Furthermore , studies using accelerometers to objective ly measure sedentary behavior conventionally operationalize sedentary time as the total number of sedentary minutes per day . This approach ignores patterns of accumulated sedentary behavior over time . For example , accumulation of sedentary time in a few long bouts or many short bouts represents 2 distinct patterns of sedentary time accrual . Experimental studies have shown that acute periods of prolonged , uninterrupted sedentary behavior cause greater detrimental cardiometabolic effects than sedentary behavior that is periodically interrupted ( 1618 ) , suggestive that it is not just total sedentary time that is relevant to health outcomes , but also the manner in which it is accumulated . Few longitudinal studies , however , have explored the association between prolonged , uninterrupted sedentary behavior and mortality to corroborate these findings . To inform guidelines on reducing sedentary behavior ( target reductions in overall sedentary time or target interruption of prolonged sedentary bouts ) , evidence from prospect i ve studies is needed to 1 ) confirm the association between total sedentary time and mortality using objective measures , 2 ) determine whether prolonged sedentary bouts confer risk for death , and 3 ) eluci date whether the total volume of sedentary time and its pattern of accumulation individually or jointly contribute to risk for death . The purpose of this study , therefore , was to examine the association between objective ly measured sedentary time ( both total volume and accrual in prolonged bouts ) and all-cause mortality in a national cohort of U.S. middle-aged and older adults enrolled in the REGARDS ( Reasons for Geographic and Racial Differences in Stroke ) study . Methods Study Population REGARDS is a population -based study design ed to examine racial and regional disparities in stroke . It comprises 30239 white and black adults aged 45 years or older enrolled between 2003 and 2007 from across the contiguous United States ( 19 , 20 ) . Detailed design and methods for REGARDS are described elsewhere ( 21 ) . Briefly , demographic and cardiovascular risk factor data were collected by telephone interview and an in-home physical assessment on enrollment . A detailed summary of baseline measures is provided in the Supplement . Participants ( or their proxies ) were then followed for 6-month intervals to ascertain vital status . Objective measurements of sedentary behavior were collected from active REGARDS participants from 2009 to 2013 ( mean time from study enrollment , 5.7 years [ SD , 1.5 ] ; range , 1.9 to 9.5 years ) ( 22 ) . A total of 7985 participants adhered to accelerometer wear requirements ( 4 days with accelerometer wear 10 hours ) , provided follow-up data , and were available for the current analyses ( Supplement Figure 1 ) . Supplement Table 1 shows the characteristics of included versus excluded REGARDS participants . The REGARDS study protocol was approved by the institutional review boards of participating institutions . All participants provided informed consent . Supplement . Supplementary Material Accelerometer Data Collection Methods for accelerometer data collection are described elsewhere ( 22 ) . Briefly , participants were fitted with an Actical ( Philips Respironics ) accelerometer secured to their right hip using a nylon belt and were instructed to wear the device during waking hours for 7 consecutive days . The Actical had been vali date d formeasurement of physical activity and sedentary behavior and was shown to have acceptable reliability ( 2325 ) . Activity counts were summed over 1-minute epochs . Nonwear periods were defined as at least 150 consecutive minutes of 0 activity counts . This nonwear algorithm was previously vali date d against daily log sheets in REGARDS participants ( 26 ) . Measurements of 0 to 49 , 50 to 1064 , and at least 1065 counts per minute were defined as sedentary behavior , light-intensity physical activity , and MVPA , respectively , as determined in a laboratory-based calibration study ( 27 ) . A sedentary bout was defined as consecutive minutes in which the accelerometer registered fewer than 50 counts per minute . A sedentary break was defined as at least 1 minute in which 50 or more counts per minute were registered after a sedentary bout . Both sedentary bouts and breaks were exclusively continuous periods , with no interruptions or nonwear intervals allowed in the definition . Outcome Ascertainment All-cause mortality was the primary outcome , defined as any death after completion of the accelerometer protocol regardless of cause . Date s of death were confirmed through review of death certificates , medical records , and administrative data bases . Deaths through 4 September 2015 were included in the current analysis . Statistical Analysis Sedentary and physical activity variables were averaged across compliant days ( 10 hours of wear ) . Because of a high correlation between total sedentary time and wear time ( Supplement Figure 2 ) , we corrected for the influence of wear time by st and ardizing total sedentary time to 16 hours of wear time per day using the residuals obtained when regressing total sedentary time on wear time ( see Methods section of the Supplement ) ( 2830 ) . Participants were stratified into quartiles according to total sedentary time and , separately , mean sedentary bout duration ( a measure of overall prolonged , uninterrupted sedentary behavior ) . Cox proportional hazards regression modeling was used to calculate the hazard ratio ( HR ) for all-cause mortality associated with quartiles of total sedentary time ( and separately , mean sedentary bout length ) . Crude HRs were initially calculated . Subsequent HRs were calculated after adjustment for age , race , sex , region of residence , education , and season the accelerometer was worn ( model 1 ) , with further adjustment for current smoking , alcohol use , body mass index ( BMI ) , diabetes , hypertension , dyslipidemia , estimated glomerular filtration rate less than 60 mL/min/1.73 m2 , atrial fibrillation , history of coronary heart disease , and history of stroke ( model 2 ) . Models were additionally adjusted for MVPA expressed continuously ( model 3 ) . Tests for linear trend across quartiles were conducted by including the quartile for each participant as an ordinal variable in regression models . Proportional hazards assumptions were confirmed with a Kolmogorov-type supremum test ( 31 ) . The above analyses were then repeated in a fully adjusted model , testing interactions for age ( < 65 and 65 years ) , sex ( male and female ) , race ( black and white ) , BMI category ( normal weight and overweight or obese ) , and MVPA category ( < 150 min/wk and 150 min/wk ) . As a secondary analysis , we examined the continuous doseresponse relationship between each sedentary characteristic and all-cause mortality in a fully adjusted model ( model 3 ) using restricted cubic splines ( 32 ) . Cubic polynomials were fitted with the mean of each sedentary characteristic set as the reference and knots placed at the 5th , 35th , 65th , and 95th percentiles ( 33 ) . Nonlinear associations were evaluated using the likelihood ratio test . For nonlinear associations , spline models were used to describe the associations and when the association was determined to be linear , a linear model was used . Because of multicollinearity between total sedentary time and mean sedentary bout duration ( r= 0.61 ) , both variables were not included in the same model . Alternatively , to examine the individual and joint associations of total sedentary time and prolonged , uninterrupted sedentary behavior with mortality , participants were classified into 4 categories : low total sedentary time ( < 750 min/d ) and low prolonged sedentary bout time ( < 10 min/bout ) , low total sedentary time  and high prolonged sedentary bout time  ( 10 min/bout ) , high total sedentary time  ( 750 min/d ) and low prolonged sedentary bout time , and high total sedentary time and high prolonged sedentary bout time . Hazard ratios for all-cause mortality were calculated for each joint category in comparison with the lowlow group in a fully adjusted model ( model 3 ) . Thresholds for total sedentary time ( 750 min/d ) and mean sedentary bout duration ( 10 min/bout ) were selected on the basis of the restricted cubic splines and were confirmed using a method described by Contal and O'Quigley ( see Methods section of the Supplement ) ( 34 ) . To allow for the possibility that sedentary bouts Objectives Evaluate the predictive validity of ActiGraph energy expenditure equations and the classification accuracy of physical activity intensity cut-points in preschoolers . Methods Forty children aged 4–6 years ( 5.3±1.0 years ) completed a ∼150-min room calorimeter protocol involving age-appropriate sedentary , light and moderate-to vigorous-intensity physical activities . Children wore an ActiGraph GT3X on the right mid-axillary line of the hip . Energy expenditure measured by room calorimetry and physical activity intensity classified using direct observation were the criterion methods . Energy expenditure was predicted using Pate and Puyau equations . Physical activity intensity was classified using Evenson , Sirard , Van Cauwenberghe , Pate , Puyau , and Reilly , ActiGraph cut-points . Results The Pate equation significantly overestimated VO2 during sedentary behaviors , light physical activities and total VO2 ( P<0.001 ) . No difference was found between measured and predicted VO2 during moderate-to vigorous-intensity physical activities ( P = 0.072 ) . The Puyau equation significantly underestimated activity energy expenditure during moderate-to vigorous-intensity physical activities , light-intensity physical activities and total activity energy expenditure ( P<0.0125 ) . However , no overestimation of activity energy expenditure during sedentary behavior was found . The Evenson cut-point demonstrated significantly higher accuracy for classifying sedentary behaviors and light-intensity physical activities than others . Classification accuracy for moderate-to vigorous-intensity physical activities was significantly higher for Pate than others . Conclusion Available ActiGraph equations do not provide accurate estimates of energy expenditure across physical activity intensities in preschoolers . Cut-points of ≤25counts⋅15 s−1 and ≥420 counts⋅15 s−1 for classifying sedentary behaviors and moderate-to vigorous-intensity physical activities , respectively , are recommended Background Little is known about the concurrent change in  physical activity ( PA )  ,  sedentary behavior ( SB ) and  sport participation  ( SP ) during adolescence . The main purpose of this prospect i ve and partly objective study was to simultaneously investigate PA , SBs and SP changes between the 1st and 2nd grade s of high school in urban adolescents . Methods In this 1-year follow-up study , the participants were 81 secondary -school students ( 28 boys and 53 girls ) aged 15.5 years at the baseline .  PA was assessed with the SenseWear Armb and multi-sensor activity monitor , while SBs were assessed by using School Health Action , Planning and Evaluation System ( SHAPES ) PA question naire . The SHAPES question naire was supplemented with two questions inquiring about SP in organized sports in school and outside of school . Results PA decreased markedly in both genders between the 1st and 2nd grade s of high school . Total energy expenditure ( TEE ) was reduced by 13 kcal/kg/day on average in boys and by 10 kcal/kg/day in girls ( p for both < 0.001 ) , while mean daily active energy expenditure ( AEE ) decreased by 7 kcal/kg/day ( p < 0.001 ) and 3 kcal/kg/day ( p = 0.04 ) in boys and girls , respectively . Similarly , the amount of moderate PA declined by 49 min/day in boys and 21 min/day in girls ( p for both < 0.001 ) . At the same time vigorous PA was cut by 14 min/day ( p < 0.001 ) and 3 min/day ( p = 0.003 ) in boys and girls , respectively . Conversely , time spent in SBs did not show any change . Conclusion In conclusion , a decline in PA between the 1st and 2nd grade s of high school was marked but was not accompanied with an increase in SBs . Policies aim ed at increasing PA should be targeting the period of entering secondary school to offset the observed drop in PA BACKGROUND Low levels of physical activity ( PA ) and highly sedentary leisure habits ( SLH ) in youth may establish behavioral patterns that will predispose youth to increased chronic disease risk in adulthood . The purpose of this paper was to examine associations of demographic and psychosocial factors with self-reported PA and SLH in young adolescents . METHODS A general linear mixed model predicted self-reported PA and SLH in the spring from demographic and psychosocial variables measured the previous fall in 3798 seventh grade students . RESULTS  PA and SLH differed by race , with Caucasian students reporting among the highest PA and lowest SLH . Perceptions of higher academic rank or expectations predicted higher  PA  and lower SLH . Depressive symptomatology predicted higher SLH scores but not PA .  Higher self-reported value of health , appearance , and achievement predicted higher PA  and lower SLH in girls . Girls who reported that their mothers had an authoritative parenting style also reported higher PA  and lower SLH . CONCLUSIONS Determinants of  PA  and SLH appear to differ from each other , particularly in boys . Development of effective programs to increase  PA  and /or decrease SLH in young adolescents should be based on a clear underst and ing of the determinants of these behaviors Objective : To assess developmental trends in physical activity and sedentary behaviour in British adolescents in relation to sex , ethnicity and socioeconomic status ( SES ) . Design : A 5-year longitudinal study of a diverse cohort of students aged 11–12 years at baseline in 1999 . Setting : 36 London schools sample d using a stratified r and om sampling procedure . Participants : A total of 5863 students categorised as white , black or Asian , and stratified for SES using the Townsend Index  . Main outcome measures : Number of days per week of vigorous activity leading to sweating and breathing hard . Hours of sedentary behaviour , including watching television and playing video games .  Data were analysed using multilevel , linear , mixed models . Results : Marked reductions in physical activity and increases in sedentary behaviour were noticed between ages 11–12 and 15–16 years . Boys were more active than girls , and the decline in physical activity was greater in girls ( 46 % reduction ) than in boys ( 23 % ) . Asian students were less active than whites , and this was also true of black girls but not boys . Black students were more sedentary than white students . Levels of sedentary behaviour were greater in respondents from lower SES . Most differences between ethnic and SES groups were present at age 11 years , and did not evolve over the teenage years . Conclusions : Physical activity declines and sedentary behaviour becomes more common during adolescence . Ethnic and SES differences are observed in physical activity and sedentary behaviour in British youth that anticipate adult variations in adiposity and cardiovascular disease risk . These are largely established by age 11–12 years , so reversing these patterns requires earlier intervention This laboratory study examined whether making sedentary activities contingent upon being physically active would increase  obese children 's physical activity . Fourteen obese children aged 8–12 y participated in a baseline session in which they had free choice among a variety of sedentary activities and riding a stationary bicycle . Children were then r and omized to either a contingent group in which watching video cassette recorder ( VCR ) movies and playing video games were contingent upon riding the bicycle or a control group in which all physical and sedentary activities remained freely available . Contingent group children increased physical activity and decreased television activities in comparison to the control , even though other sedentary activities remained freely available . Findings suggest that highly valued sedentary activities can reinforce physical activities and that sedentary activities do not completely substitute amongst themselves . The automated system used to make television activities contingent upon physical activity has potential for modifying activity in the treatment of obesity Background The quantity and quality of studies in child and adolescent physical activity and sedentary behaviour have rapidly increased , but research directions are often pursued in a reactive and uncoordinated manner . Aim To arrive at an international consensus on research priorities in the area of child and adolescent physical activity and sedentary behaviour . Methods Two independent panels , each consisting of 12 experts , undertook three rounds of a Delphi methodology . The Delphi methodology required experts to anonymously answer questions put forward by the research ers with feedback provided between each round . Results The primary outcome of the study was a ranked set of 29 research priorities that aim ed to be applicable for the next 10 years . The top three ranked priorities were : developing effective and sustainable interventions to increase children ’s physical activity long-term ; policy and /or environmental change and their influence on children ’s physical activity and sedentary behaviour ; and prospect i ve , longitudinal studies of the independent effects of physical activity and sedentary behaviour on health . Conclusions These research priorities can help to guide decisions on future research directions Background Identifying ways to promote physical activity and decrease sedentary time during childhood is a key public health issue . Research on the putative influences on preschool children ’s  physical activity ( PA ) and  sedentary behavior  ( SB ) is limited and has yielded inconsistent results . Our aim was to identify correlates of PA and SB in preschool children . Methods Cross-sectional data were drawn from the Swiss Preschoolers ’ Health Study ( SPLASHY ) , a Swiss population -based cohort study . Of 476 two to six year old children , 394 ( 54 % boys ) had valid PA data assessed by accelerometry .  Information on exposure data was directly measured or extracted from parental question naires . Multilevel linear regression modeling was used to separately assess associations between 35 potential correlates and  total PA ( TPA ) , moderate-to-vigorous PA ( MVPA ) and SB . Results In total , 12 correlates from different domains were identified . TPA and MVPA were greater in boys than girls , increased with age and were positively associated with gross motor skills . Children from single parent families had a higher level of TPA and spent less time sedentary than those living with two parents . Time spent outdoors was positively associated with TPA and negatively with SB . The child ’s activity temperament was related all three outcomes , whereas parental sports club membership , living area per person and neighborhood safety were associated with SB only . Fixed and r and om factors in the final models accounted for 28 % , 32 % and 22 % of the total variance in TPA , MVPA and SB , respectively . Variance decomposition revealed that age , sex and activity temperament were the most influential correlates of both , TPA and MVPA , whereas the child ’s activity temperament , time outdoors and neighborhood safety were identified as the most important correlates of SB . Conclusions A multidimensional set of correlates of young children ’s  activity behavior has been identified . Personal factors had the greatest influence on PA , whereas environmental-level factors had the greatest influence on SB . Moreover , we identified a number of previously unreported , potentially modifiable correlates of young children ’s PA and SB . These factors could serve to define target groups or become valuable targets for change in future interventions .Trial registration Current Controlled Trials IS RCT N41045021 ( date of registration : 21.03.14 ) The purpose s of this study were to : 1 ) describe the patterns of screen-based sedentary behaviors  , and 2 ) examine the association between  screen-based sedentary behavior and cardiovascular disease ( CVD ) risk factors in representative Korean children and adolescents , aged 12 to 18 yr , in the Korean National Health and Nutrition Examination Survey .  Screen-based sedentary behavior  was measured using self-report question naires that included items for time spent watching TV and playing PC/video games . Physical activity  was measured using items for frequency and duration of moderate-to-vigorous physical activity ( MVPA )  . CVD risk factors such as body mass index ( BMI ) , waist circumference , LDL cholesterol , HDL cholesterol , total cholesterol , triglycerides , glucose , systolic blood pressure , and diastolic blood pressure were measured . Boys spent more time playing PC/video games , and girls spent more time watching TV . After adjusting for age , gender , annual household income , and MVPA , an additional hour of watching TV was significantly associated with the risk of overweight ( OR 1.17 [ 95 % CI 1.03 - 1.33 ] ) , high abdominal adiposity ( OR 1.27 [ 1.06 - 1.51 ] ) , and low HDL cholesterol ( OR 1.27 [ 1.10 - 1.47 ] ) . An additional hour spent playing PC/video games  also increased the risk of high abdominal adiposity ( OR 1.20 [ 1.03 - 1.40 ] ) . Prospect i ve observations and interventions are needed to determine causal relationships between  screen-based sedentary behavior  and CVD risk profiles in Korean youth Background Physical activity ( PA ) is associated with positive cardio-metabolic health and emerging evidence suggests sedentary behavior ( SB ) may be detrimental to children 's health independent of PA . The primary aim of the Transform-Us ! study is to determine whether an 18-month , behavioral and environmental intervention in the school and family setting s results in higher levels of PA and lower rates of SB among 8 - 9 year old children compared with usual practice ( post-intervention and 12-months follow-up ) . The secondary aims are to determine the independent and combined effects of PA and SB on  children 's cardio-metabolic health risk factors ; identify the factors that mediate the success of the intervention ; and determine whether the intervention is cost-effective . Methods / design A four-arm cluster-r and omized controlled trial ( RCT ) with a 2 × 2 factorial design , with schools as the unit of r and omization . Twenty schools will be allocated to one of four intervention groups , sedentary behavior ( SB-I ) , physical activity ( PA-I ) , combined SB and PA ( SB+PA-I ) or current practice control ( C ) , which will be evaluated among approximately 600 children aged 8 - 9 years in school year 3 living in Melbourne , Australia . All children in year 3 at intervention schools in 2010 ( 8 - 9 years ) will receive the intervention over an 18-month period with a maintenance ' booster ' delivered in 2012 and children at all schools will be invited to participate in the evaluation assessment s. To maximize the sample and to capture new students arriving at intervention and control schools , recruitment will be on-going up to the post-intervention time point . Primary outcomes are time spent sitting and in PA assessed via accelerometers and inclinometers and survey . Discussion To our knowledge , Transform-Us ! is the first RCT to examine the effectiveness of intervention strategies for reducing children 's overall sedentary time , promoting PA and optimizing health outcomes . The integration of consistent strategies and messages to children from teachers and parents in both school and family setting s is a critical component of this study , and if shown to be effective , may have a significant impact on educational policies as well as on pedagogical and parenting practice s . Trial registration ACTRN12609000715279 ; Current Controlled Trials IS RCT BACKGROUND Encouraging adolescents to adopt healthy lifestyles can be challenging . The aim of the " Som la Pera " study was to engage adolescents by applying new strategies to increase both their fruit and vegetable consumption and their  physical activity ( PA )  while reducing their sedentary behavior . METHODS In disadvantaged neighborhoods of Reus ( Spain ) , two high schools were r and omly assigned to the intervention ( n = 170 adolescents 13- to 16-year-olds ) and two were assigned to the control group ( n = 223 adolescents 13- to 16-year-olds ) . The intervention , which lasted 12 months and spanned 2 academic years ( 2013 - 2015 ) , used social marketing ( SM ) to improve healthy choices . The peer-led strategy involved 5 adolescents who design ed and implemented 10 activities as challenges for their 165 school-aged peers . The control group received no intervention . To assess self-reported lifestyles in both groups , the Health Behavior in School-Aged Children Survey was used at baseline and end of study . RESULTS After 12 months , intervention adolescents showed an increase of 28.9 % in ≥1 fruit/day ( p < 0.01 ) and of 18.5 % in ≥6 hours/week of PA ( p < 0.01 ) compared with controls . Additionally , intervention group males had an increase of 28.8 % in ≥1 vegetable/day ( p < 0.01 ) and of 15.6 % in ≤2 hours/day of sedentary activity ( p = 0.01 ) compared with controls . CONCLUSIONS A school-based , peer-led , SM intervention developed by adolescents attending high schools in low-income neighborhoods effectively improved the healthy choices of their school-aged peers , leading to increased fruit consumption and PA in adolescents of both genders . Furthermore , adolescent males were more sensitive to improvements in healthy choices , showing increased vegetable consumption and decreased sedentary behavior BACKGROUND Sedentary behavior is associated with increased risk of chronic disease and sedentary behavior is increasing among adolescents . Data on changes in sedentary behavior in developing countries are limited . PURPOSE To describe 5-year longitudinal changes in nonschool sedentary hours among urban adolescents in Ho Chi Minh City , and to identify correlates with this change . METHODS This is a 5-year longitudinal cohort with systematic r and om sampling of 759 students from 18 junior high schools . All measures were taken annually between 2004 and 2009 .  Sedentary behavior  was assessed by self-report and accelerometry . Generalized linear latent and mixed models were used to analyze the data in 2011 . RESULTS Between 2004 and 2009 , self-reported time spent in nonschool sedentary behavior  increased from 498 to 603 minutes/day . In the 5th survey year , boys and girls ( aged 16 years ) were , respectively , 3.6 times ( 95 % CI=2.3 , 6.0 ) and 3.1 times ( 95 % CI= 1.8 , 5.0 ) more likely to spend ≥2 hours/day on screen time compared with baseline ( aged 12 years ) . Accelerometer data adjusted for wearing time revealed that boys and girls aged 16 years had , respectively , 78 minutes/day ( 95 % CI=48 , 104 ) and 69 minutes/day ( 95 % CI=34 , 95 ) more nonschool sedentary time than those at the first accelerometer assessment ( at age 13 years ) . Girls in the highest socioeconomic quartile spent an additional 90 minutes/day in sedentary behavior compared with girls in the lowest quartile ( 95 % CI=52 , 128 ) .  CONCLUSIONS Nonschool sedentary behavior  increased among Vietnamese adolescents with age . The largest increase was in recreational screen time ( 28 % ) , which would be the most obvious target for preventive health strategies BACKGROUND Underst and ing the determinants of physical activity in children is critical for the treatment and prevention of childhood obesity . Social-cognitive theory has been used to underst and behavioral patterns in children . OBJECTIVES To explore the relationship between health beliefs , self-efficacy , social support , and sedentary activities and physical  activity levels in children and to examine the relationship between physical activity and  children 's  self-esteem . METHODS Ninety-two children aged 10 to 16 years completed the study .  Physical activity was monitored for 1 week with a motion detector ( Actitrac ; IM Systems , Baltimore , Md ) . Moderate-level activity and high-level activity were defined based on the results of treadmill testing . Health beliefs , self-efficacy , social influences , and time spent in sedentary behaviors were determined through question naires . Self-esteem was measured using the Piers-Harris Children 's Self-Concept Scale . Chronic anxiety was measured with the Revised Children 's Manifest Anxiety Scale . RESULTS There was a significant decline in physical activity levels between ages 10 and 16 years , particularly in girls . Preteen girls spent approximately 35 % more time in low- and high-level activity than did teenage girls ( P<.001 ) . Overall , children spent 75.5 % of the day inactive , with a mean + /- SD of 5.2 + /- 1.8 hours watching television , sitting at the computer , and doing homework . In contrast , only 1.4 % of the day ( 12.6 + /- 12.2 minutes ) was spent in vigorous activity . Time spent in sedentary behaviors was inversely correlated with the amount of moderate-level activity ( P<.001 ) but not high-level activity . In contrast , time spent in high-level activity correlated with self-efficacy scores ( P<.001 ) and social influences scores ( P<.005 ) . High-level physical activity was also associated with improved self-esteem ( P<.05 ) . Higher health beliefs scores were not correlated with physical activity levels . CONCLUSIONS Children and adolescents are largely sedentary . Correlates of high- and low-level physical activity are different . Time spent on sedentary activities is inversely correlated with moderate-level activity , while self-efficacy and social influences are positively correlated with more intense physical activity . In addition , increased high-level physical activity is an important component in the development of self-esteem in children Objective : To determine if time spent in objective ly measured sedentary behavior is associated with a change in body mass index ( BMI ) between ages 9 and 15 years , adjusting for moderate-to-vigorous physical activity ( MVPA ) . Design : Prospect i ve observational study of children at ages 9 ( 2000 ) , 11 ( 2002 ) , 12 ( 2003 ) and 15 years ( 2006 ) .  Longitudinal quantile regression was used to model the influence of predictors on changes at the 10th , 25th , 50th , 75th and 90th BMI percentiles over time . Subjects : Participants were enrolled in the National Institute of Child Health and Human Development ( NICHD ) Study of Early Child Care and Youth Development and include both boys and girls ( n=789 ) . Measurements : Objective ly measured BMI ( kg m–2 ) was the outcome variable and objective ly measured sedentary behavior was the main predictor . Adjustment was also made for MVPA , gender , race , maternal education , hours of sleep and healthy eating index . Results : Increases in BMI were observed at all percentiles , with the greatest increase observed at the 90th BMI percentile . Spending more time in sedentary behavior  ( h per day ) was associated with additional increases in BMI at the 90th , 75th and 50th BMI percentiles , independent of MVPA and the other covariates ( 90th percentile=0.59 , 95 % confidence interval ( 95 % CI ) : 0.19–0.98 kg m–2 ; 75th percentile=0.48 , 95 % CI : 0.25–0.72 kg m–2 ; and 50th percentile=0.19 , 95 % CI : 0.05–0.33 kg m–2 ) . No associations were observed between sedentary behavior and changes at the 25th and 10th BMI percentiles . Conclusion : Sedentary behavior was associated with greater increases in BMI at the 90th , 75th and 50th BMI percentiles between ages 9 and 15 years , independent of MVPA . Preventing an increase in sedentary behavior from childhood to adolescence may contribute to reducing the number of children classified as obese Objective . To assess the effectiveness of interventions that focus on reducing  sedentary behavior ( SB ) among school-age youth and to identify elements associated with interventions ' potential for translation into practice setting s. Methods . A comprehensive literature search was conducted using 4 data bases for peer- review ed studies published between 1980 and April 2011 . R and omized trials , which lasted at least 12 weeks , aim ed at decreasing  SB among children aged 6 to 19 years were identified . Results . Twelve studies were included ; 3 focused only on SB , 1 focused on  physical activity ( PA )  , 6 were combined SB and PA interventions , and 2 studies targeted SB , PA , and diet .  The majority of the studies were conducted in a school setting , while others were conducted in such setting s as clinics , community centers , and libraries . Conclusions . Overall , interventions that focused on decreasing SB were associated with reduction in time spent on SB and /or improvements in anthropometric measurements related to childhood obesity . Several of the studies did consider elements related to the intervention 's potential for translation into practice setting BACKGROUND Epidemiological studies have shown television watching to be a risk factor for the development of obesity in children . The effect of reducing television watching and other sedentary behaviors as a component of a comprehensive obesity treatment program has not been thoroughly tested . OBJECTIVE To compare the influence of targeting decreases in sedentary behavior vs. increases in physical activity in the comprehensive treatment of obesity in 8- to 12-year-old children . DESIGN R and omized , controlled outcome study . SETTING Childhood obesity research clinic . DESIGN Ninety families with obese 8- to 12-year-old children were r and omly assigned to groups that were provided a comprehensive family-based behavioral weight control program that included dietary , and behavior change information but differed in whether sedentary or physically active behaviors were targeted and the degree of behavior change required . RESULTS Results during 2 years showed that targeting either decreased sedentary behaviors or increased physical activity was associated with significant decreases in percent overweight and body fat and improved aerobic fitness . Self-reported activity minutes increased and targeted sedentary time decreased during treatment . Children substituted nontargeted sedentary behaviors for some of their targeted sedentary behaviors . CONCLUSION These results support reducing sedentary behaviors as an adjunct in the treatment of pediatric obesity Background Previous studies examining the relationship between physical activity levels and broad-based measures of psychological wellbeing in adolescents have been limited by not controlling for potentially confounding variables . The present study examined the relationship between adolescents ’ self-reported physical activity level , sedentary behaviour and psychological wellbeing ; while controlling for a broad range of sociodemographic , health and developmental factors . Methods The study entailed a  cross-sectional school-based survey in ten British towns . Two thous and six hundred and twenty three adolescents ( aged 13–16 years ) reported physical activity levels , patterns of sedentary behaviour  ( TV/computer/video usage )  and completed the strengths and difficulties question naire ( SDQ ) .  Results Lower levels of self-reported physical activity and higher levels of sedentary behaviour showed grade d associations with higher SDQ total difficulties scores , both for boys ( P < 0.001 ) and girls ( P < 0.02 ) after adjustment for age and town . Additional adjustment for social class , number of parents , predicted school examination results , body mass index , ethnicity , alcohol intake and smoking status had little effect on these findings . Conclusions Low levels of self-reported physical activity are independently associated with diminished psychological wellbeing  among adolescents . Longitudinal studies may provide further insights into the relationship between wellbeing and activity levels in this population . Ultimately , r and omised controlled trials are needed to evaluate the effects of increasing physical activity on psychological wellbeing among adolescents
Based on 88 eligible observational studies , level of evidence grading and quantitative meta-analyses indicated that there is limited available evidence that the total volume or patterns of sedentary behaviour are associated with health in children and adolescents when accounting for moderate-intensity to vigorous-intensity physical activity or focusing on studies with low risk of bias .
Quality evidence from studies with robust design s and methods , objective measures of sitting , examining associations for various health outcomes , is needed to better underst and if the overall volume or patterns of sedentary behaviour are independent determinants of health in children and adolescents
Sedentary behaviour has emerged as a unique determinant of health in adults .
Studies in children and adolescents have been less consistent .
We review ed the evidence to determine if the total volume and patterns ( i.e. breaks and bouts ) of objective ly measured sedentary  behaviour  were associated with adverse health outcomes in young people , independent of moderate-intensity to vigorous-intensity physical activity .