Early life determinants of physical activity in 11 to 12 year olds: cohort study Physical Activity in Children Attending Preschools Prospective associations between objective measures of physical activity and fat mass in 12-14 year old children: the Avon Longitudinal Study of Parents and Children (ALSPAC) Correlates of preschool children’s objectively measured physical activity and sedentary behavior: a cross-sectional analysis of the SPLASHY study The Association of Neighborhood Design and Recreational Environments with Physical Activity Psychosocial correlates of physical activity in healthy children. Protocol for systematic reviews of determinants/correlates of obesity-related dietary and physical activity behaviors in young children (preschool 0 to 6 years): evidence mapping and syntheses The relationship between school physical activity policy and objectively measured physical activity of elementary school students: a multilevel model analysis “Pre-schoolers in the playground” an outdoor physical activity intervention for children aged 18 months to 4 years old: study protocol for a pilot cluster randomised controlled trial THE IMPACT OF PHYSICAL‐PHYSIOLOGICAL ACTIVITY ON INFANTS' GROWTH AND DEVELOPMENT Objective assessment of levels and patterns of physical activity in preschool children Objectively measured physical activity and sedentary behavior and quality of life indicators in survivors of breast cancer Effect of the Great Activity Programme on healthy lifestyle behaviours in 7–11 year olds Fundamental movement skills and habitual physical activity in young children. Physical activity to prevent obesity in young children: cluster randomised controlled trial A prospective examination of children's time spent outdoors, objectively measured physical activity and overweight Physical activity from childhood to adulthood: a 21-year tracking study.
Objective To examine factors in early life ( up to age 5 years ) that are associated with objective ly measured physical activity in 11 - 12 year olds . Design Prospect i ve cohort study . Setting Avon longitudinal study of parents and children , United Kingdom . Participants Children aged 11 - 12 years from the Avon longitudinal study of parents and children . Main outcome measure  Physical activity levels in counts per minute ( cpm )  and  minutes of moderate to vigorous physical activity for seven days measured with a uniaxial actigraph accelerometer . Results Valid actigraph data , defined as at least three days of physical activity for at least 10 hours a day , were collected from 5451 children . Several factors were associated with physical activity at ages 11 - 12 years . Regression coefficients are compared with the baseline of “ none ” for categorical variables : maternal brisk walking during pregnancy ( regression coefficient 5.0 , 95 % confidence interval −8.5 to 18.5 ; cpm for < 1 h/wk and ≥2 h/wk of physical activity 17.7 , 5.3 to 30.1 ) , maternal swimming during pregnancy ( 21.5 , 10.9 to 32.1 and cpm for < 1 h/wk and ≥2 h/wk of physical activity 24.2 , 7.8 to 40.7 ) ,  parents ’ physical activity when the child was aged 21 months  ( 28.5 , 15.2 to 41.8 and cpm of physical activity for either parent active and both parents active 33.5 , 17.8 to 49.3 ) , and parity assessed during pregnancy ( 2.9 , −7.6 to 13.4 and cpm of physical activity for 1 and ≥2 parity 21.2 , 7.1 to 35.3 ) . Conclusions Few factors in early life predicted later physical activity in 11 - 12 year olds .  Parents ’ physical activity during pregnancy and early in the child ’s life showed a modest association with physical activity of the child at age 11 - 12 years , suggesting that active parents tend to raise active children . Helping parents to increase their physical activity therefore may promote children ’s activity OBJECTIVE : To identify correlates of objective ly measured moderate and vigorous physical activity ( MVPA ) in children during preschool attendance . METHODS : This cross-sectional study included data from 426 apparently healthy Danish children ( 49.5 % boys ) , 5 to 6 years of age enrolled in 42 r and omly selected preschools . The percentage of time spent in MVPA ( ≥574 counts/15 second ) during preschool attendance was measured using ActiGraph accelerometers over 4.3 preschool days in May and June in 2009 . Thirty-seven potential correlates across the child , preschool staff , and preschool environment domains were tested for associations with MVPA . RESULTS : The final multivariate model identified 9 significant correlates of MVPA . Preterm birth , vegetation on the playground , and rainy days were negatively associated with MVPA , whereas child motor coordination , location of preschool building on the playground , gender ( boys ) , percentage afternoon hours , and size of indoor area per child were positively associated with MVPA . The direction of the significant association with the parental mean education level was unclear . CONCLUSIONS : We identified a number of new modifiable correlates  of MVPA  during preschool attendance . The positive association with size of indoor area per child and location of the preschool building on the playground seem important correlates to be targeted in future studies Objective To investigate associations between physical activity at age 12 and subsequent adiposity at age 14 . Design Prospect i ve birth cohort study with data collected between 2003 and 2007 . Setting Original recruitment in 1991 - 2 of 14 541 pregnant women living in the former County of Avon ( United Kingdom ) . Participants At age 12 , 11 952 children were invited to attend the research clinic . Of these , 7159 attended , and 4150 ( 1964 boys , 2186 girls ) provided sufficient data on exposure , outcome , and confounding variables . Main outcome measure Fat mass at age 14 , measured by dual emission x ray absorptiometry , associated with physical activity at age 12 , measured by accelerometry . Results Prospect i ve associations of fat mass at age 14 ( outcome ) with physical activity at age 12 ( exposure ) were strong for both  total activity ( accelerometer counts/min ) and for daily amount of moderate-vigorous physical activity  ( min/day ) . An extra 15 minutes of moderate-vigorous physical activity per day at age 12 was associated with lower fat mass at age 14 in boys ( by 11.9 % ( 95 % confidence interval 9.5 % to 14.3 % ) ) and girls ( by 9.8 % ( 6.7 % to 12.8 % ) ) . The proportion of physical activity due to moderate-vigorous physical activity was between 20 % and 30 % in boys and girls at the two ages . Conclusions Higher levels of physical activity , in particular activity of moderate to higher intensities , are prospect ively associated with lower levels of fat mass in early adolescence . Interventions to raise levels of physical activity in children are likely to be important in the fight against obesity 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 ) Purpose . To determine the association of neighborhood design factors and recreational environments with physical activity . Methods . R and omly selected adults ( n = 102 , 52 % female , 81 % white , mean age = 48 years ) completed a survey of eight neighborhood design variables , convenient recreational facilities , and availability of home equipment .  Physical activity was measured by self-report and 7 days of accelerometer monitoring . Results . Residential density and an overall environment index were significantly related to both vigorous-intensity self-reported ( r = .35 and .28 , respectively ) and objective ly measured physical activity ( r = .39 and .23 , respectively ) . Home equipment was correlated with self-reported total ( r = .34 ) and vigorous leisure-time physical activity ( r = .27 ) . The vigorous and total activity accelerometer measures were correlated with street connectivity ( r = .25 and .21 , respectively ) . Discussion . Few self-reported neighborhood design factors and recreational environment variables were correlated with physical activity , and some findings were unexpected 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 Background The aim of these review s is to inform the design and content of interventions to reduce obesity in young children . The behaviors that are associated with obesity/overweight have been studied extensively ; however , the factors associated with these behaviors in young children ( 0 to 6 years ) have not been systematic ally review ed . Over the past few years the focus of obesity prevention has shifted to preschool children because of the high prevalence of obesity at school entry and recognition that habits formed in early life could track into adulthood . In order to develop effective interventions and change behavior , it is important to underst and the factors that are associated with those behaviors . For example , we need to underst and whether it would be more important to target the family , childcare setting s or the wider environment and identify the most effective way of changing these energy balance related behaviors . Methods / Design Quantitative ( intervention and observational ) and qualitative literature on determinants/correlates of fruit and vegetable intake , sugar sweetened beverage and other unhealthy diet intake , and physical activity and sedentary behaviors in young children will be systematic ally identified , mapped and review ed . A common search strategy ( no language or period restrictions ) will be used to identify papers from eight electronic data bases and this will be supplemented by h and - search ing . Next , studies in developed countries that examine the factors associated with these behaviors in children aged 0 to 6 years ( at baseline ) will be screened and mapped descriptively followed by in-depth data extraction , quality assessment and synthesis . Data from quantitative studies will be summarized using either forest plots or harvest plots and narrative synthesis , and qualitative studies using thematic analysis . Qualitative evidence will be integrated with the quantitative evidence , using a parallel synthesis approach , to provide a deeper underst and ing of effective strategies to influence these energy balance related behaviors . Discussion In addition to updating and mapping current research , these review s will be the first to comprehensively synthesize and integrate both the quantitative and qualitative evidence pertaining to determinants/correlates/barriers/facilitators of obesity related behaviors in this young age group ( 0 to 6 years ) with the aim of informing future interventions . Systematic review registration International Prospect i ve Register for Systematic Review s ( PROSPERO ) Registration number : Background There is evidence of school level variability in the physical activity of children and youth . Less is known about factors that may contribute to this variation . The purpose of this study was to examine if the school health environment ( Healthy Physical Environment , Instruction and Programs , Supportive Social Environment , and Community Partnerships ) is associated with objective ly measured time spent in light to vigorous physical activity among a sample of Toronto children . Methods The sample comprised 856 grade 5 and 6 students from 18 elementary schools in Toronto , Ontario .  Multilevel linear regression analyses were used to examine the impact of school physical activity policy on students ’ time spent in light-to-vigorous physical activity . Results Significant between-school r and om variation in objective ly measured time spent in light-to-vigorous physical activity was identified [ σ2μ0 = 0.067 ; p < 0.001 ] ; school-level differences accounted for 6.7 % of the variability in the time individual students spent in light-to-vigorous physical activity . Of the 22 school-level variables , students attending schools with support for active transportation to/from school and written policies/ practice s for physical activity , accumulated significantly more minutes of physical activity per school week than students who attended schools that did not . Conclusions School physical activity policy and support for active school travel is associated with objective ly measured time spent in light to vigorous physical activity . School physical activity policy might be a critical mechanism through which schools can impact the physical activity levels of their students Background The pre-school years are considered critical for establishing healthy lifestyle behaviours such as physical activity . Levels of physical activity track through childhood into adulthood , thus establishing habitual physical activity early in life is vital . Time spent outdoors is associated with greater physical activity and playground interventions have been shown to increase physical activity in school aged children . There are few pre-school , playground-based interventions , and evaluations of these have found mixed results . A recent report published by the UK Chief Medical Officer ( CMO ) highlighted that new interventions to promote movement in the early years ( 0–5 years old ) are needed . The aim of this study is to undertake a pilot cluster r and omised controlled trial ( RCT ) of an outdoor playground-based physical activity intervention for parents and their children aged 18 months to 4 years old ( “ Pre-schoolers in the Playground ” ; PiP ) and to assess the feasibility of conducting a full scale cluster RCT . The PiP intervention is grounded in behavioural theory ( Social Cognitive Theory ) , and is in accordance with the CMO guidance for physical activity in the early years . It is informed by existing literature and data collected from focus groups with parents . Methods / Design One hundred and fifty pre-school children affiliated to 10 primary schools will be recruited . Schools will be r and omised to either the PiP intervention arm or the control arm ( usual practice ) . Children in the intervention arm will be invited to attend three 30 minute outdoor play sessions per week for 30 weeks ( 3 school terms ) at the school . Feasibility will be assessed by examining recruitment rates , attendance , attrition , acceptability of the trial and of the PiP intervention to parents , fidelity of intervention implementation , capability and capacity for schools to deliver the intervention . Health outcomes and the feasibility of outcome measurement tools will be assessed . These include physical activity via triaxial , accelerometry ( Actigraph GT3X+ ) , anthropometry ( height , body mass , BMI , waist and upper arm circumference ) , health related quality of life for child ( PedsQL ) and parent ( EQ5D ) , parent wellbeing ( ComQol-A5 ) , injuries and health service use . A health economic evaluation will also be undertaken . Discussion It is anticipated that results of this pilot trial will be published in spring 2015.Trial registration Current controlled trials : IS RCT Forty‐seven infants four to 40 weeks of age in Dumaguete City , the Philippines , were given a cycling motion exercise of the upper and lower limbs for Jour five‐minute periods a day , six days a week , for two months . They were measured , against a control group of 17 infants of the same age and sex . Pretest , mid test , and pastiest measurements were taken for weight gain , length gain , and development of motor , language , adaptive , and personal‐social behaviors . Significant differences were found between the two groups of infants to substantiate the hypothesis that increases in growth and development of infants who receive physical care and emotional support plus planned physical‐physiological activity in the form of passive cycling exercises would be greater than those of infants who receive only physical care and , emotional support Background : The aim of this study was to examine in detail levels and patterns of physical activity in preschool children and the effects of gender and BMI on this activity . Methods : Two hundred and fifty-three children aged 5 y participating in the Copenhagen Prospect i ve Studies on Asthma in Childhood wore an accelerometer day and night over a 4-wk period . The main outcome measure was level of physical activity using the raw data . A secondary measure was time spent in moderate to vigorous physical activity ( MVPA ) . A Fourier series analysis was applied to study in detail patterns over time . Results : Activity profiles throughout the year were unique for each sex , with boys being overall more active than girls except for winter months . Preschool children also showed distinct patterns of physical activity during weekdays as compared with weekends and were most active during weekdays . Preschool children in the highest tertile of BMI had a flat yearly activity profile and tended to be less active as compared with those in the lowest tertile . Conclusion : Preschool children showed significant gender differences in physical activity , with distinct patterns throughout the year as well as between weekdays and weekends . A high BMI tended to be associated with lower levels of physical activity The primary purpose of the current study was to determine prospect i ve associations of accelerometer‐assessed physical activity intensity and sedentary time with health‐related quality of life ( HRQOL ) indicators among survivors of breast cancer Abstract The study investigated the effect of a school-based healthy lifestyles intervention on physical activity and dietary variables . In total 378 children ( 177 intervention , 201 control ; age 9.75 ± 0.82 years ( mean ± s ) ) took part in the 7-month intervention comprising : preparation for and participation in 3 highlight events ( a dance festival , a walking event and a running event ) ; an interactive website for pupils , teachers and parents ; and vacation activity planners . Primary outcome measures were objective ly measured physical activity ( pedometers and accelerometers ) , endurance fitness and dietary variables . Multi-level modelling was employed for data analysis . The increase in physical activity was greater in the intervention group than the control group ( steps : 1049 vs 632 daily steps each month ; moderate to vigorous physical activity ( MVPA ) total : 4.6 min · day−1 · month−1 vs 1.3 min · day−1 · month−1 ; MVPA bouts : 5.4 min · day−1 · month−1 vs 2.6 min · day−1 · month−1 ; all P < 0.05 ) . The increase in multi-stage fitness test distance was greater for intervention participants ( 46 vs 29 m · month−1 of intervention , group × month interaction , P < 0.05 ) . There were no differences between groups in dietary variables , body composition , knowledge of healthy lifestyles or psychological variables . Thus an intervention centred around highlight events and including relatively few additional re sources can impact positively on the objective ly measured physical activity of children PURPOSE To test for relationships between objective ly measured habitual physical activity and fundamental movement skills in a relatively large and representative sample of preschool children . METHODS Physical activity was measured over 6 d using the Computer Science and Applications ( CSA ) accelerometer in 394 boys and girls ( mean age 4.2 , SD 0.5 yr ) . Children were scored on 15 fundamental movement skills , based on the Movement Assessment Battery , by a single observer . RESULTS Total physical activity ( r=0.10 , P<0.05 ) and percent time spent in moderate to vigorous physical activity ( MVPA ) ( r=0.18 , P<0.001 ) were significantly correlated with total movement skills score . Time spent in light-intensity physical activity was not significantly correlated with motor skills score ( r=0.02 , P>0.05 ) . CONCLUSIONS In this sample and setting , fundamental movement skills were significantly associated with habitual physical activity , but the association between the two variables was weak . The present study questions whether the widely assumed relationships between motor skills and habitual physical activity actually exist in young children Objective To assess whether a physical activity intervention reduces body mass index in young children . Design Cluster r and omised controlled single blinded trial over 12 months . Setting Thirty six nurseries in Glasgow , Scotl and . Participants 545 children in their preschool year , mean age 4.2 years ( SD 0.2 ) at baseline . Intervention Enhanced physical activity programme in nursery ( three 30 minute sessions a week over 24 weeks ) plus home based health education aim ed at increasing physical activity through play and reducing sedentary behaviour . Main outcome measure Body mass index , expressed as a st and ard deviation score relative to UK 1990 reference data . Secondary measures were objective ly measured physical activity and sedentary behaviour ; fundamental movement skills ; and evaluation of the process . Results Group allocation had no significant effect on the primary outcome measure at six and 12 months or on measures of physical activity and sedentary behaviour by accelerometry . Children in the intervention group had significantly higher performance in movement skills tests than control children at six month follow-up ( P=0.0027 ; 95 % confidence interval 0.3 to 1.3 ) after adjustment for sex and baseline performance . Conclusions Physical activity can significantly improve motor skills but did not reduce body mass index in young children in this trial . Trial registration Current Controlled Trials IS RCT N36363490 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 BACKGROUND The aim of this study was to investigate stability of physical activity  from childhood and adolescence to adulthood in multiple age cohorts , and analyze how well adult physical activity can be predicted by various physical activity variables measured in childhood and adolescence . METHODS The data were drawn from the Cardiovascular Risk in Young Finns Study . The study was started in 1980 , when cohorts of r and omly sample d boys and girls aged 3 , 6 , 9 , 12 , 15 , and 18 years ( total of 2309 subjects ) were examined for the first time . The measurements were repeated in 1983 , 1986 , 1989 , 1992 , and 2001 . In 2001 , the subjects ( n = 1563 , 68 % ) were aged 24 , 27 , 30 , 33 , 36 , and 39 years , respectively .  Physical activity  was measured by means of a short self-report question naire that was administered individually in connection with a medical examination . On the basis of a question naire , a physical activity index ( PAI ) was calculated . There were no significant differences in the 1980 PAI between participants and dropouts in 2001 . RESULTS Spearmans rank order correlation coefficients for the 21-year tracking period varied from 0.33 to 0.44 in males , and from 0.14 to 0.26 in females . At shorter time intervals the correlation was higher . On average , the tracking correlation was lower in females than in males . Persistent physical activity , defined as a score in the most active third of the PAI in two or three consecutive measurements , increased the odds that an individual would be active in adulthood . Odds ratios for 3-year continuous activity versus continuous inactivity varied from 4.30 to 7.10 in males and 2.90 to 5.60 in females . The corresponding odds ratios for 6-year persistence were 8.70 to 10.80 and 5.90 to 9.40 . CONCLUSIONS It was concluded that a high level of physical activity at ages 9 to 18 , especially when continuous , significantly predicted a high level of adult physical activity . Although the correlations were low or moderate , we consider it important that school-age physical activity appears to influence adult physical activity , and through it , the public health of the general population
Physical activity interventions were consistently ( > 60 % of studies ) associated with improved motor and cognitive development , and psychosocial and cardiometabolic health .
Across observational studies , physical activity was consistently associated with favourable motor development , fitness , and bone and skeletal health .
For intensity , light- and moderate-intensity physical activity were not consistently associated with any health indicators , whereas moderate- to vigorous-intensity , vigorous-intensity , and total physical activity were consistently favourably associated with multiple health indicators .
Across study design s , consistent favourable associations with health indicators were observed for a variety of types of physical activity , including active play , aerobic , dance , prone position ( infants ; ≤1 year ) , and structured/organized .
Apart from ≥30 min/day of the prone position for infants , the most favourable frequency and duration of physical activity was unclear .
However , more physical activity appeared better for health .
Conclusions Specific types of physical activity , total physical activity , and physical activity of at least moderate- to vigorous-intensity were consistently favourably associated with multiple health indicators .
Background Given the rapid development during the early years ( 0 - 4 years ) , an underst and ing of the health implication s of physical activity is needed .
The purpose of this systematic review was to examine the relationships between objective ly and subjectively measured physical activity and health indicators in the early years .