The Physical Activity 4 Everyone Cluster Randomized Trial: 2-Year Outcomes of a School Physical Activity Intervention Among Adolescents. A Novel Approach to Characterize Physical Activity Patterns in Preschool-Aged Children 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. Exploring effective strategies for increasing the amount of moderate-to-vigorous physical activity children accumulate during recess: a quasi-experimental intervention study. The effect of a classroom activity break on physical activity levels and adiposity in primary school children. Physical activity, sedentary behavior, and adiposity in English children. Physical activity growth curves relate to adiposity in adolescents. MVPA Is Associated with Lower Weight Gain in 8–10 Year Old Children: A Prospective Study with 1 Year Follow-Up Development of an Accelerometer-Linked Online Intervention System to Promote Physical Activity in Adolescents Promoting physical activity in middle school girls: Trial of Activity for Adolescent Girls. Reducing Sedentary Behavior Versus Increasing Moderate-to-Vigorous Intensity Physical Activity in Older Adults The Patterns of Moderate to Vigorous Physical Activity and Physical Education Enjoyment Through a 2-Year School-Based Program. A cluster randomised trial of a school-based intervention to prevent decline in adolescent physical activity levels: study protocol for the ‘Physical Activity 4 Everyone’ trial Assessment of a two-year school-based physical activity intervention among 7-9-year-old children Children's physical activity levels during school recess: a quasi-experimental intervention study Personal and social-environmental correlates of objectively measured physical activity in Norwegian pre-adolescent children. Improving health-enhancing physical activity in girls' physical education.
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 Objective Routine moderate-to-vigorous physical activity ( MVPA ) is associated with better health outcomes ; the purpose of this work was to evaluate healthy preschooler physical activity patterns with objective measurement . Methods and Procedures An objective prospect i ve study of fifty normally-developing children 3–5 years old who were ≥50th and < 95th BMI percentile and enrolled in a family-based healthy lifestyle study in 2011–2012 . Participants wore a tri-axial accelerometer for 7 continuous days . Outcome measures consisted of wear time examining four common MVPA patterns : isolated spurt ( IS ) , isolated sustained activity ( ISA ) , clustered spurt ( CS ) , and clustered sustained activity ( CSA ) . Results Participants were 4.3 years , 56 % female , 52 % African-American , and 26 % overweight . Forty-five children met wear time criteria . On average , children spent 14.5 % of wake-wear time in MVPA , requiring 11.3 hours to complete 90 % of their daily MVPA . Children spent the majority of MVPA in CS ( 62.1 % , followed by CSA ( 20.1 % ) . Remaining MVPA was spent in IS ( 15.5 % ) and ISA ( 2.3 % ) . Conclusion It takes most of the waking day for preschoolers to attain their PA . They engage in short spurts of small duration , in four common MVPA patterns . Utilizing this method could better characterize preschooler physical activity needs in practice and policy guidelines 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 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 AIM Despite recognition that regular physical activity is essential for good health , many children do not accumulate sufficient daily physical activity . The aim of this study was to examine the effect of a classroom-based activity break on accelerometer-determined moderate-to-vigorous intensity physical activity ( MVPA ) and adiposity in primary school children . METHODS One hundred twenty children from seven primary schools in Northern Irel and participated in the study . In each school , one class of children was r and omly assigned to an intervention group and another class to a control group . Teachers of the intervention classes led a 5-min activity break three times per day for 12 weeks .  Accelerometer-determined MVPA , height , weight and four skinfolds  were measured at baseline and post-intervention . RESULTS Compared with the control group , the intervention group significantly increased weekday MVPA ( + 9.5 min ) from baseline to post-intervention . There were no significant changes in BMI ; however , an increase in sum-of-skinfolds of the intervention group was observed . CONCLUSIONS Classroom-based activity breaks led by the teacher are successful in increasing  children 's  physical activity levels . The programme shows a positive step in improving overall physical activity levels and contributing to the goal of 60 min daily MVPA 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 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 Studies relating physical activity ( PA ) to  weight gain in children have produced mixed results , although there is some evidence for stronger associations with more intense physical activities . The present study tested the hypothesis that weight gain over one year in 8–10 year olds would be more strongly predicted by moderate and vigorous physical activity ( MVPA ) than total physical activity ( total PA ) or sedentary behaviour . Methodology Participants were 280 children taking part in the Physical Exercise and Appetite in Children Study ( PEACHES ) .  Weight status was assessed using body mass index ( BMI ) , fat mass index ( FMI ) , and waist circumference ( WC ) in school Year 4 ( baseline ; age 8.7 yrs ) and Year 5 ( follow-up ; age 9.7 yrs ) .  Physical activity  was measured at baseline using the Actigraph GT1 M accelerometer to assess total PA ( mean accelerometers counts per minute ) , MVPA ; ≥4000 counts per minute ) and sedentary time  ( < 100 counts per minute ) . Principal Findings After adjustment for baseline BMI , SES , sex and ethnicity , MVPA  was significantly associated with follow – up BMI ( adjusted β = −0.07 ; p = 0.002 ) . This association was independent of total PA or sedentary time  . Similar results were observed for FMI ; again MVPA was significantly associated with follow up FMI ( β = −0.16 ; p = 0.001 ) independent  of total PA or sedentary time . The pattern was similar for WC ( β = −0.07 ) , but the association between MVPA and WC did not reach significance at p = 0.06 . Conclusion The results of this study strongly support promotion of MVPA in children 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 BACKGROUND Physical activity is important for weight control and good health ; however , activity levels decline in the adolescent years , particularly in girls . DESIGN Group r and omized controlled trial . SETTING / PARTICIPANTS Middle school girls with English-speaking skills and no conditions to prevent participation in physical activity in 36 schools in six geographically diverse areas of the United States . R and om , cross-sectional sample s were drawn within schools : 6th grade rs in 2003 ( n=1721 ) and 8th grade rs in 2005 ( n=3504 ) and 2006 ( n=3502 ) . INTERVENTION A 2-year study -directed intervention ( fall 2003 to spring 2005 ) targeted schools , community agencies , and girls  to increase opportunities , support , and incentives for increased physical activity . Components included programs linking schools and community agencies , physical education , health education , and social marketing . A third-year intervention used school and community personnel to direct intervention activities . MAIN OUTCOME MEASURES The primary outcome , daily MET-weighted minutes of moderate-to-vigorous physical activity ( MET-weighted MVPA ) , was assessed using accelerometry . Percent body fat was assessed using anthropometry . RESULTS After the staff-directed intervention ( pre-stated primary outcome ) , there were no differences ( mean= -0.4 , 95 % CI= -8.2 to 7.4 ) in adjusted MET-weighted MVPA between 8th- grade girls in schools assigned to intervention or control . Following the Program Champion-directed intervention , girls in intervention schools were more physically active than girls in control schools ( mean difference 10.9 MET-weighted minutes of MVPA , 95 % CI=0.52 - 21.2 ) . This difference is about 1.6 minutes of daily MVPA or 80 kcal per week . There were no differences in fitness or percent body fat at either 8th- grade timepoint . CONCLUSION A school-based , community-linked intervention modestly improved physical activity in girls Objective : To compare the effects of behavioral interventions targeting decreased sedentary behavior versus increased moderate-to-vigorous intensity physical activity ( MVPA ) in older adults . Method : Inactive older adults ( N = 38 , 68 ± 7 years old , 71 % female ) were r and omized to 12-week interventions targeting decreased sedentary behavior ( Sit Less ) or increased MVPA ( Get Active ) . The SenseWear armb and was used to objective ly assess activity in real time . Assessment s included a blinded armb and , the Community Health Activites Model Program for Senior ( CHAMPS ) question naire , 400-meter walk , and the Short Physical Performance Battery ( SPPB ) . Results : Objective ly measured MVPA increased in Get Active ( 75 ± 22 min/week , p < .001 ) ; self-reported MVPA increased in both groups ( p < .05 ) . Sedentary behavior did not change in either group ( all p > .05 ) . Only the Sit Less group improved the SPPB score ( 0.5 ± 0.3 , p = .046 ) . Discussion : Targeting reduced sedentary behavior had a greater effect on physical function among inactive but high functioning older adults over 12 weeks . Future studies of longer duration and combining increased MVPA with reduced sedentary behavior are needed 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 Background Adolescence is an established period of physical activity decline . Multi-component school-based interventions have the potential to slow the decline in adolescents ’ physical activity ; however , few interventions have been conducted in schools located in low-income or disadvantaged communities . This study aims to assess the effectiveness of a multi-component school-based intervention in reducing the decline in physical activity among students attending secondary schools located in disadvantaged communities . Methods / Design The cluster r and omised trial will be conducted with 10 secondary schools located in selected regions of New South Wales , Australia . The schools will be selected from areas that have a level of socio-economic status that is below the state average . Five schools will be allocated to receive an intervention based on the Health Promoting Schools framework , and will be supported by a part-time physical activity consultant placed in intervention schools who will implement a range of intervention adoption strategies . Study measures will be taken at baseline when students are in Year 7 ( 12–13 years ) and again after 12- and 24-months . The primary outcome , minutes of moderate- to-vigorous- intensity physical activity per day and percentage of time in moderate- to vigorous-intensity physical activity ( MVPA ) , will be objective ly assessed using accelerometers ( Actigraph GT3x+ ) . Group allocation and intervention delivery will commence after baseline data collection . The intervention will continue during school terms through to 24-month follow-up . Discussion The study will provide evidence regarding the effectiveness of a multi-component school-based intervention that includes an in-school physical activity consultant targeting the physical activity levels of adolescents in disadvantaged Australian secondary schools . Trial registration Australian New Zeal and Clinical Trials Registry ACTRN12612000382875 Background  Physical activity ( PA )  in children has declined in recent decades , highlighting the need for effective intervention programs for school-aged children . The main objective of this study was to assess to what extent PA during and after school hours changed among children who received a progressive two-year long intervention vs. that of children who only received general curriculum-based PA .  Methods A cluster r and omized intervention study was conducted and six elementary schools r and omly assigned to serve as control- or intervention schools . All children attending second grade ( mean age = 7.4 years - born in 1999 ) were invited to participate in the fall of 2006 ( N = 320 , 82 % participated ) , again in 2007 ( midpoint ) and 2008 ( end of intervention ) . The intervention consisted of multi-component PA-intervention during school hours and was conducted by teachers at each intervention school . PA  was assessed by means of accelerometers and subjectively at the intervention schools via teachers ' PA log-books . Results There was no difference in PA intensity ( minutes of moderate-to-vigorous physical activity - min of MVPA ) between the two study groups at baseline , but children in the intervention schools were more physically active at moderate-to-vigorous intensity compared to those in control schools after one year of intervention ( mean difference of MVPAlog-minutes : 0.61 , 95%CI : 0.02 , 1.20 , p = 0.04 ) . Moreover , the model for minutes of MVPA during school hours , showed a significant three-way interaction between time at mid-point , group and gender ( mean difference of MVPAlog-minutes : 1.06 , 95%CI : 0.15 , 1.97 , p = .02 ) , indicating a significantly greater increase among the boys in the intervention schools compared to girls . No difference in PA was detected between the study groups at the end of the study period after two years of intervention . Conclusions The results suggest that the objective of increasing PA at school was met after one year of intervention , and it was more pronounced among boys . The lack of increase at the end of the study period suggested that any increase in  PA  during school may highly depend on both motivation and training of general teachers . Boys may respond better to PA interventions such as the one described in this study Background Recess provides a daily opportunity for children to engage in moderate-to-vigorous ( MVPA ) and vigorous physical activity ( VPA ) . Limited research has investigated the effects of recess-based interventions on physical activity using large sample sizes whilst investigating variables that may influence the intervention effect . The aim of the study was to investigate the short-term effects of a playground markings and physical structures intervention on recess physical activity .  A secondary aim was to investigate the effects of covariates on the intervention . Methods 150 boys and 147 girls were r and omly selected from 26 elementary schools to wear uni-axial accelerometers that quantified physical activity every 5 seconds during recess . Fifteen schools located in deprived areas in one large urban city in Engl and received funding through a national initiative to re design the playground environment . Eleven schools served as matched socioeconomic controls . Data were collected at baseline and 6-weeks following playground intervention .  Recess MVPA and VPA levels adjusted for pupil- and school-level covariates ( baseline physical activity , age , gender , recess length , body mass index ) were analysed using multilevel analyses . Results Positive but non-significant intervention effects were found for MVPA and VPA when confounding variables were added to the model . Gender was a significant predictor of recess physical activity , with boys engaging in more MVPA and VPA than girls . Significant interactions for MVPA revealed that the intervention effect was stronger for younger elementary aged school children compared to older children , and the intervention effect increased as daily recess duration increased . Conclusion The playground re design intervention result ed in small but non-significant increases in children 's  recess physical activity when school and pupil level variables were added to the analyses . Changing the playground environment produced a stronger intervention effect for younger children , and longer daily recess duration enabled children to engage in more MVPA following the intervention . This study concludes that the process of increasing recess physical activity is complex when school and pupil-level covariates are considered , though they should be taken into account when investigating the effects of playground intervention studies on children 's physical activity during recess 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 This study examined the effectiveness of an intervention to increase  levels of moderate-to-vigorous intensity physical activity ( MVPA )  during girls ' physical education lessons . Two Year 7 classes ( age 11 - 12 years ) were r and omly appointed to control and experimental groups . Both followed the same six-lesson unit of gymnastics with identical lesson objectives . The experimental class teacher included the additional objective of increasing MVPA during each lesson . MVPA  was assessed in all six lessons using heart rate ( HR ) monitoring and systematic observation . After each lesson , students ' intrinsic motivation and perceived competence were assessed , and the teachers evaluated whether they had met planned objectives . The experimental group engaged in more  MVPA  [ F(1 , 21 ) = 8.49 , P = 0.008 ( HR ) , t8 = -2.35 , P = 0.048 ( observation ) ] than the control group and also had most opportunities for skill practice ( t8 = -2.81 , P = 0.023 ) . Intrinsic motivation and perceived competence levels were similar between the groups for each lesson , and teachers reported that lesson objectives were satisfactorily achieved . This intervention succeeded in increasing MVPA without compromising intrinsic motivation , perceived competence or planned lesson objectives
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 .