Physical activity, sedentary behavior, and adiposity in English children. Personal and social-environmental correlates of objectively measured physical activity in Norwegian pre-adolescent children. Physical activity growth curves relate to adiposity in adolescents. The Patterns of Moderate to Vigorous Physical Activity and Physical Education Enjoyment Through a 2-Year School-Based Program. Developmental Trajectories of Physical Activity, Sports, and Television Viewing During Childhood to Young Adulthood: Iowa Bone Development Study. The relative influence of demographic, individual, social, and environmental factors on physical activity among boys and girls Exploring effective strategies for increasing the amount of moderate-to-vigorous physical activity children accumulate during recess: a quasi-experimental intervention study. Sustained effects of physical activity on bone health: Iowa Bone Development Study. Cross-sectional and prospective associations between sleep, screen time, active school travel, sports/exercise participation and physical activity in children and adolescents Physical activity and femoral neck bone strength during childhood: the Iowa Bone Development Study. Time spent in sedentary behavior and changes in childhood BMI: a longitudinal study from ages 9 to 15 years Design of the Trial of Activity in Adolescent Girls (TAAG). Volume and intensity of physical activity in a large population-based cohort of middle-aged and older Australians: prospective relationships with weight gain, and physical function. Intrapersonal, social and physical environmental determinants of moderate-to-vigorous physical activity in working-age women: a systematic review protocol School physical education: effect of the Child and Adolescent Trial for Cardiovascular Health. Development of an Accelerometer-Linked Online Intervention System to Promote Physical Activity in Adolescents A Longitudinal Study of the Family Physical Activity Environment and Physical Activity among Youth A prospective examination of children's time spent outdoors, objectively measured physical activity and overweight The Physical Activity 4 Everyone Cluster Randomized Trial: 2-Year Outcomes of a School Physical Activity Intervention Among Adolescents.
BACKGROUND The importance of variation in total volume of physical activity or moderate- to vigorous-intensity physical activity ( MVPA ) to development of body fatness in childhood is unclear , and it is unclear if physical activity has a greater influence on adiposity in boys than girls . PURPOSE To assess relationships between 2-year changes in objective ly measured physical activity , sedentary behavior , and adiposity in English children . METHODS Prospect i ve cohort study , set in Northeast Engl and , of a socioeconomically representative sample of 403 children . Measures were change in accelerometer-determined physical activity and sedentary behavior  from age 7 to 9 years ( data collected 2006/2007 and 2008/2009 ; analyzed in 2010 ) and concurrent change in adiposity ( fat mass index derived from bioelectric impedance ) and change in BMI Z-score . RESULTS Decline in MVPA was associated with a greater increase in fat mass index in boys but not girls . Declining MVPA was associated with increased BMI Z-score in boys but not girls . Increased sedentary behavior was not associated with increased BMI Z-score in either gender . CONCLUSIONS Avoiding mid-late childhood reductions in MVPA may reduce excessive fat gain , although such strategies may have greater impact on boys than girls The aim of this study was to examine modifiable biological , psychological , behavioral and social-environmental correlates of physical activity among 1129 Norwegian 11-year-old children within a cross-sectional sample from the HEalth In Adolescents study .  Physical activity was assessed by accelerometer , and weight and height were measured objective ly . Age- and gender-specific cut-off points proposed by the International Obesity Task Force were used to define body mass index . Social-environmental variables were self-reported by question naire . Hierarchical regression ( linear mixed models ) revealed that normal weight children scored higher on percentage daily moderate-to-vigorous physical activity [ % daily moderate to vigorous physical activity ( MVPA ) ] than overweight/obese children ( P<0.001 ) . Self-efficacy ( P<0.01 ) and perceived social support from friends ( P<0.01 ) were positively associated with children 's % daily MVPA , and a negative association was found for computer/game-use on weekends ( P<0.01 ) . A moderator effect of weight category ( normal vs overweight/obese ) in the relationship between computer/game-use on weekends and % daily MVPA was detected ( P<0.05 ) , reflecting that higher computer/game-use on weekends was associated with lower % MVPA among the overweight/obese , but not among the normal weight . Modifiable correlates from multiple domains accounted for 14 % of the variance in % daily MVPA . Prospect i ve and intervention studies are needed to examine whether these factors act as mediators for physical activity change in pre-adolescent children PURPOSE Findings from prospect i ve studies on associations between physical activity and adiposity among youth are inconsistent . Our aim was to describe physical activity trajectories during secondary school and examine the association with change in adiposity in youth . METHODS  Physical activity  was measured in 20 survey cycles from 1999 to 2005 ; anthropometrics were measured in survey cycles 1 , 12 , and 19 . Individual growth curves modeling moderate-to-vigorous physical activity ( MVPA ) and vigorous physical activity ( VPA ) were estimated . Estimates of initial level and rate of decline in MVPA and VPA bouts per week were included as potential predictors of body fat% and body mass index using age- and sex-specific linear regression . RESULTS Complete data were available for 840 and 760 adolescents aged 12 - 13 years at baseline , followed from survey cycles 1 - 12 and 12 - 19 , respectively . Among girls , yearly declines of one MVPA and one VPA bout per week during earlier adolescence were associated with increases of 0.19 ( 95 % confidence interval [ CI ] , 0.02 - 0.36 ) and 0.47 ( 95 % CI , 0.015 - 0.92 ) units of body fat% , respectively . In boys , a yearly decline of one MVPA bout per week was associated with an increase of 0.38 ( 95 % CI , 0.05 - 0.70 ) units of body fat% during later adolescence . CONCLUSIONS Obesity prevention programs should include strategies to prevent declines in physical activity BACKGROUND In this study , we examined the development of children 's moderate to vigorous physical activity ( MVPA ) and physical education ( PE ) enjoyment through the Physical Activity as Civil Skill Program 2012 - 2014 . METHODS Participants were 661 ( 265 intervention , 396 control ) elementary school children in central and northeast Finl and . The program was implemented across 2 years with 3 measurement phases using self-reported MVPA and PE enjoyment , and accelerometer-determined  MVPA  of a r and om sub sample ( N = 76 ) . RESULTS The proportion of children meeting the current MVPA guidelines declined from 38 % to 22 % ( intervention ) and 14 % to 9 % ( control ) , whereas PE enjoyment was stable in both groups . Boys were more physically active than girls only within control group children . Teachers ' feedback indicated that violence and bullying among intervention students reduced during the program , which can be considered as an additional benefit . CONCLUSIONS It may be that both  MVPA  and  PE  enjoyment may require more tailored actions to be increased across a long-term program . It is important to ensure that school-based physical activity programs , especially including transition from elementary to middle school level , provide all children positive experiences , and thus , may improve their motivation , and  MVPA  participation during school days and leisure time IMPORTANCE The diverse developmental patterns of obesogenic behaviors during childhood and adolescence can be better understood by using new analytic approaches to assess the heterogeneity in variation during growth and development and to map the clustering of behavior patterns . OBJECTIVES To identify distinct trajectories of daily time spent in  moderate- to vigorous-intensity physical activity ( MVPA )  from ages 5 to 19 years and to examine the associations of MVPA trajectories with sports participation and television viewing trajectories . DESIGN , SETTING , AND PARTICIPANTS Cohort members in the prospect i ve population -based Iowa Bone Development Study participated in  MVPA assessment s via accelerometry from September 16 , 1998 , to December 9 , 2013 , at ages 5 , 8 , 11 , 13 , 15 , 17 , and 19 years and completed a question naire every 6 months on sports participation and daily time spent in television viewing . MAIN OUTCOMES AND MEASURES Trajectories of MVPA ( minutes per day ) , participation in organized sports ( yes or no ) , and television viewing time ( hours per day ) . RESULTS Based on the data from 537 participants ( 50.1 % females ; 94.6 % white ) , we identified 4 MVPA trajectories : consistently inactive ( 14.9 % ) , consistently active ( 18.1 % ) , decreasing moderate physical activity ( 52.9 % ) , and substantially decreasing high physical activity ( 14.1 % ) . All participants in the consistently inactive trajectory also followed a trajectory of no participation in sports . The consistently active trajectory was associated with decreasing an already low television viewing trajectory ( P < .001 ) . CONCLUSIONS AND RELEVANCE This study provided a nuanced look at the known decrease in MVPA during childhood and adolescence . Sports participation could be a critical way to avoid the consistently inactive pattern . Most important , we identified a subset of participants who maintained a seemingly healthy level of MVPA from childhood to young adulthood . The developmental pathways of physical activity and television viewing behaviors could be related . Additional studies should examine the determinants and health consequences of these specific MVPA trajectories Background This study aim ed to evaluate the associations of selected demographic , individual , social , and environmental factors with moderate-to-vigorous physical activity ( MVPA ) in a sample of children and adolescents . Methods  MVPA  was assessed among youth ( n = 294 ) 10 - 17-years-old using the ActiGraph accelerometer . Youth completed measures of demographic and individual variables related to physical activity ( PA ) , perceived social support by parents and peers , and perceived neighborhood characteristics . Parents completed the long-form of the International Physical Activity Question naire . The Physical Activity and Media Inventory was used to measure the home environment and Geographical Information Systems software was used to measure the physical neighborhood environment . Bivariate correlations and hierarchical multiple regression were conducted stratified by gender . Results Boys participated in significantly more MVPA than girls . In hierarchical analyses , peer support , home PA equipment , and temperature were significantly associated with MVPA among boys whereas distance to the school they attended was associated with MVPA among girls . The final models accounted for 25 % and 15 % of the variance in MVPA among boys and girls , respectively . Conclusions Important differences exist among the individual , social , and environmental factors related to MVPA between boys and girls . Boys ' levels of activity appear to be influenced by factors closely linked to unstructured and social types of activities whereas girls ' activities relate to internal and external barriers as well as their proximity to their schools . The prospect i ve contribution of these important individual , social , and environmental factors to changes in MVPA among children and adolescents remains to be determined BACKGROUND Less than half of elementary children meet the physical activity recommendations of 30 to 60 minutes of moderate-to-vigorous physical activity ( MVPA ) on a daily basis . Recess provides the single biggest opportunity for children to accumulate MVPA . This study explored whether a teacher 's social prompting to be active during recess alone and modeling of active recess-time games alone may increase the amount of MVPA children accumulate during recess . METHODS Three demographically matched schools were r and omly assigned to receive a social prompting intervention , modeling intervention , or to serve as a comparison group . Pre- and postintervention physical activity data was collected utilizing accelerometers . RESULTS Compared with preintervention , MVPA during recess increased significantly in the social prompting group and decreased significantly in the modeling group . There were no significant changes in the comparison group . There was a significant interaction between time and intervention : pre- to postintervention change between interventions was significant for modeling versus comparison and modeling versus social prompting , but not for social prompting versus comparison . CONCLUSIONS Modeling was not an effective strategy for increasing MVPA during recess . Social prompting may be an effective strategy for increasing MVPA during recess . However , larger studies are needed to determine whether social prompting increases MVPA during recess . In light of evidence suggesting that MVPA is linked to lower obesity rates , and a substantial number of health and academic benefits , social prompting may be a useful strategy to further explore to address the childhood obesity epidemic , and improve students ' health and academic outcomes Studies of youth athletics and interventions have shown some maintenance of bone mineral content ( BMC ; g ) after cessation of training , but less is known about sustained effects of everyday physical activity ( PA ) . Using a prospect i ve cohort , this report examined potential effects of  childhood PA  on  adolescent BMC . Participants ( N=156 boys , 170 girls ) had exams at ages 5 , 13 , and 15 . Body size and maturity were determined using anthropometry . Moderate-to-vigorous-intensity PA ( MVPA ) and vigorous-intensity PA ( Vigorous PA ) were measured using accelerometry .  BMC of the spine and hip was measured using dual-energy X-ray absorptiometry . Mixed regression models tested whether PA at age 5 affected BMC at ages 13 and 15 after adjustment for age ( year ) , height ( cm ) , weight ( kg ) , maturity ( pre-peak height velocity or post ) , and activity level ( min/day ) . Analysis was repeated to control for age 5 BMC . On average , boys participated in 59 , 52 , and 38 min of MVPA and 13 , 17 , and 11 min of Vigorous PA at ages 5 , 13 , and 15 , respectively . MVPA ( β=0.799 ) and Vigorous PA ( β=1.338 ) at age 5 predicted later spine BMC ( p<0.05 ) . MVPA ( β=0.480 ) at age 5 predicted hip BMC . Girls participated in 47 , 33 , and 26 min of MVPA and 10 , 9 and 7 min of Vigorous PA at ages 5 , 13 , and 15 , respectively . Neither MVPA nor Vigorous PA  predicted later spine BMC . MVPA ( β=0.302 ) at age 5 predicted hip BMC . After controlling for BMC at age 5 as well as the other covariates , the effect of MVPA ( β=0.695 ) and Vigorous PA ( β=1.079 ) at age 5 remained significant for boys at the spine . For girls , neither MVPA nor Vigorous PA at age 5 predicted spine or hip BMC . Children 's early PA  appears to have a modest effect on  adolescent BMC at the critical regions of spine and hip ; benefits may be greater for geometric changes , which future studies should include Background The aim of this study was to investigate how sleep , screen time , active school travel and sport and /or exercise participation associates with moderate-to-vigorous physical activity ( MVPA ) in nationally representative sample s of Norwegian 9- and 15-y-olds , and whether these four behaviors at age nine predict change in MVPA from age nine to 15 years . Method We pooled cross-sectional accelerometer and question naire data  from 9- ( n = 2366 ) and 15-y-olds ( n = 1554 ) that participated in the first ( 2005/06 ) and second ( 2011/12 ) wave of the Physical Activity among Norwegian Children Study to investigate cross-sectional associations . To investigate prospect i ve associations , we used data from a sub- sample that participated in both waves ( at age nine and 15 years , n = 517 ) . Results Cross-sectional analyses indicated a modest , inverse association between screen time and MVPA among 9- ( − 2.2 min/d ( 95 % CI : -3.1 , − 1.3 ) ) and 15-y-olds ( − 1.7 min/d ( 95 % CI : -2.7 , − 0.8 ) ) . Compared to their peers with 0–5 min/d of active travel to school , 9- and 15-y-olds with ≥16 min/d accumulated 7.2 ( 95 % CI : 4.0 , 10.4 ) and 9.0 ( 95 % CI : 3.8 , 14.1 ) more min/d of MVPA , respectively . Nine-y-old boys and 15-y-olds reporting ≥8 h/week of sports and /or exercise participation accumulated 14.7 ( 95 % CI : 8.2 , 21.3 ) and 17.9 ( 95 % CI : 14.0 , 21.8 ) more min/d of MVPA , respectively , than those reporting ≤2 h/week . We found no cross-sectional association between sleep duration and MVPA in either age group . None of the four behaviors predicted change in MVPA from age nine to 15 years ( p ≥ 0.102 ) . Conclusion Active travel to school and sport/exercise participation may be important targets for future interventions aim ed at increasing MVPA in children and adolescents . However , future studies are needed to determine causality Structural adaptations of bone to changing mechanical loads have recently been documented during adolescence . However , little is known about how bone adapts structurally during the earlier years . Using a longitudinal observational design spanning 6 years of growth ( age range 4 to 12 years ) , we investigated associations between everyday physical activity and hip geometry in a cohort of healthy Midwestern children ( n=468 ) . Femoral neck ( FN ) cross sectional area ( CSA , cm(2 ) ) and FN section modulus ( Z , cm(3 ) ) were used to describe hip geometry . CSA and Z , indices of axial and bending strength , were assessed using dual-energy X-ray absorptiometry ( DXA ) scans and the hip structure analysis ( HSA ) program . Moderate and vigorous physical activity ( MVPA ) was assessed using accelerometry-based activity monitors and calculated as the number of minutes > or = 3000 accelerometry movement counts . Data were analyzed using multilevel ( r and om- and fixed-effects ) regression models with adjustment for age ( year ) , height ( cm ) , and weight ( kg ) or lean mass ( kg ) . For boys and girls , MVPA was a positive independent predictor of CSA and Z ( p<0.05 ) . On average , children who participated in 40 min of MVPA per day would be expected to have 3 % to 5 % greater CSA and Z than peers participating in 10 min of MVPA per day . Ten-minute increases in daily MVPA had similar effects on CSA in girls and Z in boys as did each additional 1 kg of body weight . When lean mass was substituted for weight , MVPA continued to be a positive independent predictor of CSA and Z for boys , but not girls . This study demonstrates that everyday amounts of physical activity in children are associated with indices of FN bone strength during childhood . Differences in lean mass mediate associations between physical activity and hip geometry in girls , but only somewhat in boys . These results suggest that physical activity is an important contributor to bone strength prior to adolescence and that increasing levels of physical activity during childhood are likely to enhance optimal bone strength 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 The primary aim of the Trial of Activity in Adolescent Girls ( TAAG ) is to test an intervention to reduce by half the age-related decline in moderate to vigorous physical activity  ( MVPA ) in middle school girls . The intervention will be evaluated using a group-r and omized trial involving 36 middle schools . The primary endpoint is the mean difference in intensity-weighted minutes ( i.e. , MET-minutes ) of MVPA between intervention and comparison schools assessed using accelerometry . The TAAG study design calls for two cross-sectional sample s , one drawn from 6th grade rs at the beginning of the study and the second drawn from 8th grade rs at the end of the study following the 2-year implementation of the intervention . An important strength of this design over a cohort design is the consistency with the goals of TAAG , which focus on environmental-level rather than individual-level interventions to produce change . The study design specifies a recruitment rate of 80 % and a smaller sample of girls at baseline ( n=48 per school ) than at follow-up ( n=96 per school ) . A two-stage model will be used to test the primary hypothesis . In the first stage , MET-weighted minutes of MVPA will be regressed on school , time ( baseline or follow-up ) , their interaction , ethnicity and week of data collection . The second stage analysis will be conducted on the 72 adjusted means from the first stage . In the main-effects model , we will regress the follow-up school mean MET-weighted minutes of MVPA on study condition , adjusting for the baseline school mean . The TAAG study addresses an important health behavior , and also advances the field of group-r and omized trials through the use of a study design and analysis plan tailored to serve the main study hypothesis OBJECTIVES To examine prospect ively whether higher proportions of vigorous physical activity ( VPA ) , independent of total activity volume , are associated with better outcomes in weight maintenance and physical function . METHODS We used three-year longitudinal data ( 2006/07 - 2009/10 ) of adults 45 and older ( n=32,087 ; 59.5±9.3years ) from New South Wales , Australia . Logistic regression models examined odds of weight gain and functional decline by volume and intensity of physical activity . RESULTS On average , body weight increased by 0.66 kg ( SD=5.83 , p<0.001 ) ; a vali date d physical function score ( MOS-PF ) decreased by 4.79 ( SD=12.56 , p<0.001 ) . There was a 10 % reduction in the odds of weight gain for participants who reported 300min/week or more of moderate to vigorous physical activity ( MVPA ) compared to less than 150min of MVPA . The proportion of MVPA that was vigorous was not associated with weight change . With the physical functioning outcome , there were independent protective effects from volume and intensity of physical activity . Independent of total MVPA , each 1 % increase in the proportion of total activity that was vigorous was associated with a 0.3 % decrease in the odds of decline in physical function . CONCLUSION These prospect i ve findings indicate that VPA per se plays an important role in the prevention of functional decline Background The majority of North American adult females do not meet current physical activity recommendations ( 150 min of moderate-to-vigorous intensity physical activity ( MVPA ) per week accrued in ≥10 min bouts ) ultimately placing themselves at increased risk of morbidity and mortality . Working-age females face particular challenges in meeting physical activity recommendations as they have multiple dem and s , including occupational , family and social dem and s. To develop effective interventions to increase MVPA among working-age females , it is necessary to identify and underst and the strongest modifiable determinants influencing these behaviours . Therefore , the objective of this systematic review is to examine the available evidence to identify intrapersonal , social and environmental determinants of MVPA among working-age females . Methods / Design Six electronic data bases will be search ed to identify all prospect i ve cohort studies that report on intrapersonal , social and /or environmental determinants of  MVPA  in working-age females . Grey literature sources including theses , published conference abstract s and websites from relevant organizations will also be included . Articles that report on intrapersonal ( e.g. health status , self-efficacy , socio-economic status ( SES ) , stress , depression ) , social environmental ( e.g. crime , safety , area SES , social support , climate and capital , policies ) , and environmental ( e.g. weather , workplace , home , neighbourhood , recreation environment , active transportation ) determinants of MVPA  in a working-age ( mean age 18–65 years ) female population will be included . Risk of bias will be assessed within and across all included studies using the Tool to Assess Risk of Bias in Cohort Studies and the Grade s of Recommendation , Assessment , Development and Evaluation approach . Harvest plots will be used to synthesize results across all determinants , and meta-analyses will be conducted where possible among studies with sufficient homogeneity . Discussion This review will provide a comprehensive examination of evidence in this field and will serve to highlight gaps for future research on the determinants of MVPA in working-age females and ultimately inform intervention design . Systematic review registration PROSPERO : CRD42014009750 BACKGROUND Physical inactivity is a risk behavior for cardiovascular and other diseases . Schools can promote public health objectives by increasing physical activity among youth . METHODS The Child and Adolescent Trial for Cardiovascular Health ( CATCH ) was a multicenter , r and omized trial to test the effectiveness of a cardiovascular health promotion program in 96 public schools in four states . A major component of CATCH was an innovative , health-related physical education ( P+ ) program . For 2.5 years , r and omly assigned schools received a st and ardized PE intervention , including curriculum , staff development , and follow-up . RESULTS Systematic analysis of 2,096 PE lessons indicated students engaged in more moderate-to-vigorous physical activity ( MVPA ) in intervention than in control schools ( P = 0.002 ) . MVPA during lessons in intervention schools increased from 37.4 % at baseline to 51.9 % , thereby meeting the established Year 2000 objective of 50 % . Intervention children reported 12 more min of daily vigorous physical activity ( P = 0.003 ) and ran 18.6 yards more than control children on a 9-min run test of fitness ( P = 0.21 ) . CONCLUSIONS The implementation of a st and ardized curriculum and staff development program increased children 's  MVPA in existing school PE classes in four geographic and ethnically diverse communities . CATCH PE provides a tested model for improving physical education in American schools Most adolescents do not achieve the recommended levels of moderate-to-vigorous physical activity ( MVPA ) , placing them at increased risk for a diverse array of chronic diseases in adulthood . There is a great need for scalable and effective interventions that can increase MVPA in adolescents . Here we report the results of a measurement validation study and a preliminary proof-of-concept experiment testing the impact of Zamzee , an accelerometer-linked online intervention system that combines proximal performance feedback and incentive motivation features to promote MVPA . In a calibration study that parametrically varied levels of physical activity in 31 12 - 14 year-old children , the Zamzee activity meter was shown to provide a valid measure of MVPA ( sensitivity in detecting MVPA = 85.9 % , specificity = 97.5 % , and r = .94 correspondence with the benchmark RT3 accelerometer system ; all p < .0001 ) . In a subsequent r and omized controlled multi-site experiment involving 182 middle school-aged children assessed for MVPA over 6 wks , intent-to-treat analyses found that those who received access to the Zamzee intervention had average MVPA levels 54 % greater than those of a passive control group ( p < 0.0001 ) and 68 % greater than those of an active control group that received access to a commercially available active videogame ( p < .0001 ) . Zamzee ’s effects on MVPA did not diminish significantly over the course of the 6-wk study period , and were statistically significant in both females and males , and in normal- vs. high- BMI subgroups . These results provide promising initial indications that combining the Zamzee activity meter with online proximal performance feedback and incentive motivation features can positively impact MVPA levels in adolescents Purpose . Although the family environment is a potentially important influence on children 's  physical activity ( PA )  , prospect i ve data investigating these associations are lacking . This study aim ed to examine the longitudinal relationship between the family environment and PA among youth . Design . A 5-year prospect i ve cohort study . Setting . Nineteen r and omly selected public schools in Melbourne , Australia . Subjects . Families of 5- to 6-year-old ( n = 190 ) and 10- to 12-year-old ( n = 350 ) children . Measures . In 2001 , parents reported their participation in PA , family-based PA , and support and reinforcement for their child 's PA . In 2001 , 2004 , and 2006 ,  moderate to vigorous intensity PA ( MVPA )  was assessed among youth using accelerometers .  Weekend and “ critical window ” ( after school until 6:00 P.M. ) MVPA were examined because we hypothesized that the family environment would most likely influence these behaviors . Analysis . Generalized estimating equations predicted average change in MVPA over 5 years from baseline family environment factors . Results . Maternal role modeling was positively associated with boys ' critical window and weekend ( younger boys ) MVPA .  Paternal reinforcement of PA  was positively associated with critical window and weekend MVPA among all boys , and paternal direct support was positively associated with weekend MVPA ( older boys ) . Among girls , maternal coparticipation in PA predicted critical window MVPA , and sibling coparticipation in PA was directly associated with weekend MVPA ( younger girls ) . Conclusions . Longitudinal relationships , although weak in magnitude , were observed between the family environment and MVPA among youth . Interventions promoting maternal role modeling , paternal reinforcement of and support for PA , and maternal and sibling coparticipation in PA with youth are warranted . ( Am J Health Promot 2011;25[3]:159–167 . Objective : This study aim ed to determine whether time spent outdoors was associated with objective ly measured physical activity , body mass index ( BMI ) z-score and overweight in elementary-school aged children , cross-sectionally and prospect ively over 3 years . Methods : Three-year cohort study with data collected during 2001 and 2004 . Nineteen r and omly selected state elementary schools across Melbourne , Australia . One hundred and eighty eight 5–6-year-old and 360 10–12-year-old children . Baseline parent reports of children 's time spent outdoors  during warmer and cooler months , on weekdays and weekends . At baseline and follow-up , children 's moderate and vigorous physical activity ( MVPA ) was objective ly assessed by accelerometry , and BMI z-score and overweight was calculated from measured height and weight . Results : Cross-sectionally , each additional hour outdoors on weekdays and weekend days during the cooler months was associated with an extra 27 min week−1 MVPA among older girls , and with an extra 20 min week−1 MVPA among older boys . Longitudinally , more time outdoors on weekends predicted higher MVPA on weekends among older girls and boys ( 5 min week−1 ) . The prevalence of overweight among older children at follow-up was 27–41 % lower among those spending more time outdoors at baseline . Conclusion : Encouraging 10–12-year-old children to spend more time outdoors may be an effective strategy for increasing physical activity and preventing increases in overweight and obesity . Intervention research investigating the effect of increasing time outdoors on children 's physical activity and overweight is warranted INTRODUCTION Few interventions have been successful in reducing the physical activity decline typically observed among adolescents . The aim of this paper is to report the 24-month effectiveness of a multicomponent school-based intervention ( Physical Activity 4 Everyone ) in reducing the decline in moderate to vigorous physical activity ( MVPA ) among secondary school students in disadvantaged areas of New South Wales , Australia . STUDY DESIGN A cluster RCT was conducted in five intervention and five control schools with follow-up measures taken at 24 months post-r and omization . SETTING / PARTICIPANTS The trial was undertaken within secondary schools located in disadvantaged communities in New South Wales , Australia . INTERVENTION A multicomponent school-based intervention based on the Health Promoting Schools Framework was implemented . The intervention consisted of seven physical activity promotion strategies that targeted the curriculum ( teaching strategies to increase physical activity in physical education lessons , student physical activity plans , and modification of school sport program ) ; school environment ( recess/lunchtime activities , school physical activity policy ) ; parents ( parent newsletters ) ; and community ( community physical activity provider promotion ) . Six additional strategies supported school implementation of the physical activity intervention strategies . MAIN OUTCOME MEASURE Minutes per day spent in MVPA , objective ly measured by accelerometer . RESULTS Participants ( N=1,150 , 49 % male ) were a cohort of students aged 12 years ( Grade 7 ) at baseline ( March-June 2012 ) and 14 years ( Grade 9 ) at follow-up ( March-July 2014 ) . At 24-month follow-up , there were significant effects in favor of the intervention group for daily minutes of MVPA . The adjusted mean difference in change in daily MVPA between groups was 7.0 minutes ( 95 % CI=2.7 , 11.4 , p<0.002 ) ( analysis conducted December 2014-February 2015 ) . Sensitivity analyses based on multiple imputation were consistent with the main analysis ( 6.0 minutes , 95 % CI=0.6 , 11.3 , p<0.031 ) . CONCLUSIONS The intervention was effective in increasing adolescents ' minutes of MVPA , suggesting that implementation of the intervention by disadvantaged schools has the potential to slow the decline in physical activity . TRIAL REGISTRATION Australian New Zeal and Clinical Trials Registry ACTRN12612000382875
The relative decline in MVPA affects both sexes from an early age ; however , it is greater among girls .
Moderate-to-vigorous-intensity  physical activity ( MVPA )  is important for childhood obesity prevention and treatment , yet declines with age .
Timing and magnitude of the decline in MVPA in children and adolescents are unclear but important for informing effective obesity intervention development .
This systematic review aim ed to determine and compare the year-to-year changes in MVPA among children and adolescents .