  childhood overweight prevalence is increasing globally , with over 42 million children under 5 years already overweight .
overweight children are at risk for various chronic diseases ( e.g. , cardiovascular diseases , diabetes )   and often remain overweight as adults .
the preschool age has specifically been indicated as the most critical growth period for future overweight development .
these habits are formed at a young age and often maintained during later life [ 6 , 7 ] .
targeting physical activity in early childhood is therefore essential to prevent overweight throughout life . in europe ,
moreover , various studies have shown an increased overweight risk in children attending childcare [ 911 ] .
the childcare setting offers a potential opportunity for environmental interventions to promote physical activity among young children [ 12 , 13 ] .
such interventions can only be systematically designed after the most important environmental determinants of physical activity have been identified .  
a review of correlates of preschool children 's physical activity level showed that the preschool a child attends is significantly associated with the child 's total physical activity .
several authors have called for additional research to identify the specific characteristics of preschools that explain variance in physical activity levels between preschools and childcare centers [ 16 , 17 ] .
however , previous studies mostly summarize or quantify the physical environment into one measure for activity opportunities ( e.g. , using the environment and policy assessment and observation ( epao ) instrument or its subscales ) or overall quality of the facility ( e.g. , using the early childhood environment rating scale ( ecers - r ) ) , examining the association between such general scores and activity levels [ 2026 ] .
although it is very informative to see whether improving general childcare quality is associated with increased physical activity , it does not provide concrete leads for childcare organizations regarding which factors they can improve in the physical environment to facilitate children 's physical activity .
the few studies that have previously examined specific characteristics of the physical childcare environment have linked increased physical activity to colour markings at playgrounds , but evidence regarding other specific factors such as playground equipment is lacking .
the current study therefore examined the association of several specific , separate , physical activity facilities in the physical childcare environment ( e.g. , play equipment ) , with the physical activity level of 2- and 3-year olds at childcare .
all nine childcare centers of a large childcare coordinating organization in maastricht , the netherlands , were approached to participate in the study .
the coordinating organization gave consent to conduct the study and all childcare centers agreed to participate .
the childcare centers each catered care for an average of 92 ( sd = 28 ) children , of which an estimated 12% ( sd = 14% ) were of non - dutch origin . on average , there were 5 groups ( sd = 1 ) and 20 staff members ( sd = 6 ) per center .
parents were informed about the study in a letter and were able to refuse participation , although none of the parents did so .  
each childcare centre was visited three times in may and/or june of 2008 : once for an interview with the center manager and a rating of the physical activity facilities and twice for direct observations of children 's activity level .
the observations were performed by two observers , both trained in using the instruments described below .
the physical activity level was observed by a momentary sampling procedure with observations lasting 15 seconds each .
this procedure was repeated four times over a period of three minutes for each child . each child
was observed for two nonconsecutive blocks of four observations . in total , 10 children were observed per center per day , resulting in a total of 80 observations .
this protocol was implemented on two days for each of the nine centers , during one morning and one afternoon , with at least one week between the two observation days .
this resulted in 2880 single observations regarding 180 children ( 2 observers  9 centers  2 days / center  10 children / day  2 blocks / child  4 observations / block ) . during the observations ,
physical activity level was assessed by means of a translated version of the observational system for recording physical activity in children - preschool version ( osrac - p ) . in line with the osrac - p protocol ,
mean activity intensity during the observation periods ( 15 seconds ) was assessed on a scale from 1 ( sedentary ) to 5 ( highly active ) .
activity levels 2 were regarded as sedentary and activity levels 4 as moderate and vigorous physical activity ( mvpa ) .
the physical childcare environment ( i.e. , physical activity facilities ) was rated using translated items of the environment and policy assessment and observation instrument ( epao [ 18 , 29 ] ) .
the epao instrument assesses the accessibility of the physical environment , that is , the presence of physical activity facilities such as play equipment .  
subscales of the epao were used , for example , portable and fixed play equipment , and an additional subscale for total size of the playing area .
portable equipment was rated by checking the availability of 9 types of equipment : balls , climbing structures ( e.g. , ladders ) , floor play equipment ( e.g. , tumbling mats ) , jumping equipment ( e.g. , jump ropes , hula hoops ) , push / pull toys ( e.g. , wagons ) , riding toys ( e.g. , tricycles , cars ) , slides , sand / water toys ( e.g. , buckets , scoops ) , and twirling equipment ( e.g. , ribbons , batons ) . fixed equipment was rated in a similar manner for structured tracks ( e.g. , playground markings ) , merry - go - rounds , climbing structures ( e.g. , jungle gyms ) , see - saws , slides , tunnels , balancing surfaces ( e.g. , balance beams ) , sandboxes , and swinging equipment ( e.g. , swings , ropes ) .
all play equipment was rated as either present ( 1 ) or not ( 0 ) .
total playing area was rated on a scale from 0 ( no playing area ) to 10 ( very large area ) .
background information regarding the childcare centers , such as the number of enrolled children , was recorded during interviews with the manager of each childcare center .
in addition , child 's sex and age were assessed by asking present staff after the observations were finished .
p values < .05 were considered statistically significant . for activity level , the mean of the scores of both observers was calculated .
cohen 's kappa was used to determine the interrater reliability ( irr ) of the two observers .
the irr was .7 ( p < .001 ) in the current study , indicating substantial agreement .
the distribution of the physical activity facilities and the mean activity levels corresponding to the presence and absence of these facilities were explored .
the significance of the differences between the activity levels with and without the facilities present were examined using t - tests .
the association between total playing area and the physical activity level was examined using pearson 's correlations .
next , we conducted backward regression analyses with the physical activity facilities and child characteristics ( age and sex ) as independent variables and the activity level as the outcome variable .
insignificant independent variables were stepwise deleted from the model in order of their significance , starting with the least significant variable .
stepwise multilevel linear model analyses with 3 levels ( i.e. , measurement level ; child level ; center level ) were executed to examine the association between activity level and the physical activity facilities , while modeling the interdependence between observations within individuals and between individuals within childcare centers . in the starting model ,
random intercepts at the child and center level were included , as well as a first - order autoregressive ( ar(1 ) ) correlation structure for repeated measures .
furthermore , random slopes at the centre level were included for child sex and age .
insignificant random effects were backward removed from the model , starting with the least significant random effect .
the fixed effects were then examined analogous to the regression analyses described above ( i.e. , through the backward procedure ) .
we performed both the multivariate analyses where we corrected for the multilevel structure of data , and those without correction of the data , because the multilevel analyses might unintentionally overcorrect for the dependence between repeated measures within one subject in case an activity lasted longer than the duration of a single observation period ( i.e. , 45 seconds ) .
this might especially be the case for various sedentary activities , such as playing in the sandbox .
five children were not present during the observations , leading to a total of 175 children that were each observed eight times .
data regarding 18 observation periods were missing because these children were absent during one or more of the eight observation periods ( e.g. , because parents had already picked them up ) , which left 1382 observation periods for analyses .
the mean age was 2.6 years , with 75 two - year olds ( 42.9% ) and 100 three - year olds ( 57.1% ) .
most of the time the weather was sunny with clear skies ( 37.7% ) ; least prevalent weather type was rain ( 11.4% ) .
the mean activity intensity level during indoor observations was 2.36 ( on a scale from 1 to 5 ) .
only 5.5% of the indoor physical activity observations were classified as mvpa ( moderate and vigorous physical activity ; activity level 4 ) , whereas 59.4% were classified as sedentary behavior ( activity level 2 ) .
outdoors , the mean activity level was 2.82 , with 21.3% being mvpa , and 31.2% being sedentary . 

table 1 provides an overview of the physical activity facilities in the 9 childcare centers .
indoors , all childcare centers provided balls and floor play equipment , and most ( 89% ) also had portable and fixed climbing structures such as ladders and jungle gyms available .
none of the centers had an indoor structured track , merry - go - round , tunnel , sandbox , or swinging equipment .
the mean size of the indoor playing area was rated 6.11 ( sd = 2.21 ) on a scale from 1 ( no playing area ) to 10 ( very large playing area ) .   in line with indoors ,
in addition , all centers had push or pull toys and riding toys available outdoors , as well as sand or water toys and balancing surfaces .
most centers ( 89% ) also provided fixed climbing structures , fixed slides , and a sandbox outdoors .
none of the observed childcare centers had a merry - go - round or twirling equipment available outdoors .
the size of the outdoor playground was rated with an average of 6.22 ( sd = 3.07 ) . 

table 1 shows the mean activity levels corresponding to the indoor facilities being either present or not .
children were significantly more active indoors if jumping equipment , push or pull toys , portable slides , fixed slides or balancing surfaces were available indoors .
the size of the indoor playing area was significantly positively correlated with children 's activity levels ( correlation coefficient r = .17 , p < .001 ) . 

table 2 shows the adjusted associations of the background factors and indoor physical activity facilities with indoor activity levels , with and without correction for the multilevel structure of the data ( i.e. , regression analyses and multilevel analyses , resp . ) .
both analyses show that riding toys are negatively associated with children 's indoor activity levels , while the size of the playing area is positively associated with the activity levels .
the mean activity levels of the children in the childcare centers where the various outdoor facilities were either present or not are presented in table 1 .
the children were significantly more active in case floor play equipment , jumping equipment , a structured track , fixed climbing structures , fixed slides , tunnels , or a sandbox were available outdoors .
none of the outdoor physical activity facilities was associated with a lower activity level in the bivariate analyses .
the size of the outdoor playground was significantly positively correlated with children 's activity level ( r = .13 , p = < .001 ) .  

table 3 shows the adjusted associations of the background factors and outdoor physical activity facilities with outdoor activity levels , with and without correction for the multilevel structure of the data .
the analyses without correction for the multilevel structure of the data ( the regression analyses ) show that older children were significantly more active outdoors than younger children .
furthermore , portable jumping equipment and having a structured track showed a positive association with outdoor activity levels .
portable slides , sandboxes , and swinging equipment outdoors were negatively associated with children 's activity level .
however , in the multilevel analyses , only the presence of a structured track was still positively associated with children 's activity levels .
the current study examined the association between the availability of various physical activity facilities at the childcare center and 2- and 3-year olds ' physical activity levels . in general , children 's activity levels were comparable to those found in an earlier study applying the same protocol in us childcare centers ( mean overall activity level 2.55 , compared to 2.59 in the current study ) . with regard to the associations with physical activity facilities , the study showed different results for indoor and outdoor observations .   indoors , children were more active when more space was available for playing .
this is in line with a previous study by cardon and colleagues , who found that the number of children per square meter was inversely correlated with activity levels , although this study regarded outdoor activity .
we failed to find such an inverse association between the size of the playing area and activity levels outdoors .
.   took the number of children present also into account , which we did not .
also qualitative studies among childcare workers often mention space limitations as an important barrier for sufficient physical activity ( e.g. , [ 33 , 34 ] ) . in line with what could be expected from previous studies , which summarized the facilities assessed in the current study into one measure for activity opportunities and found a positive association between those activity opportunities and activity levels [ 21 , 22 ] ,
children were significantly more active when jumping equipment was present , as well as when a fixed track was marked on the playground .
the latter is in line with an experimental study that showed that multicolor playground markings can increase children 's activity levels , even in the long run .
however , there were also several play facilities that were found to be inversely associated with children 's activity levels .
indoors the availability of riding toys seemed to decrease children 's activity levels , and outdoors portable slides , sandboxes , and swinging equipment were associated with lower activity levels . with regard to the riding toys ,
in addition , many childcare centers have safety policies or rules that limit vigorous physical activity such as running or riding very fast on a bike [ 3336 ] .
children in sandboxes are most of the time sitting , squatting , or standing , which explains the inverse association between sandboxes and activity level . with regard to slides and swings , we believe the negative association might stem from the fact that only one child can use these facilities at a time , and the other children are standing still , waiting for their turn .
moreover , once the child is using these equipments , he or she is again mainly sitting still .
many facilities that seem activity promoting at first glance thus appear to have the opposite effect on children 's physical activity .  
the negative associations found between various facilities and children 's activity levels make the use of  activity opportunity " sum scores such as the epao score   ( of which we used the separate components in the current study ) at least questionable : not all supposed activity promoting facilities seem to actually be activity - promoting .
however , the differences between the bivariate analyses and the multivariate analyses demonstrate that one can also not take only one or a few of the facilities into account when looking at the influence of the physical childcare environment on children 's activity levels .
the sandbox is a good example of this . in the bivariate analyses , the presence of a sandbox at a childcare center
in practice , childcare centers that have a sandbox probably also have many other facilities available that do increase children 's activity levels , because they have a larger budget for play facilities for instance , and it is actually a confounding effect that explains the positive bivariate association between the sandbox and activity levels . indeed
, secondary chi - square tests showed that the childcare centers that had a sandbox also significantly ( p < .001 ) more often had various other physical activity facilities available , including jumping equipment and a structured track at the playground , which were both found to be positively associated with outdoor activity levels . in conclusion ,
studies examining influences of the physical childcare environment on children 's activity level could probably best include a wide range of facilities , for instance , based on existing observation instruments such as the epao instrument , but refrain from summarizing these facilities into one measure for activity opportunities or childcare quality [ 2026 ] .  
several facilities were provided in either all childcare centers ( i.e. , balls indoor and outdoor , indoor floor play equipment and outdoor push or pull toys , riding toys , sand or water toys and balancing surfaces ) or in none of the centers ( i.e. , indoor structured track , merry - go - round , tunnels , sandboxes , and swinging equipment and outdoor merry - go - round or twirling equipment ) in the current study . in case of the facilities that were present in
none of the centers , this partly has to do with cultural differences between the netherlands ( in which the present study was conducted ) and the usa ( in which the epao instrument was developed ) .
merry - go - rounds , for instance , are not common on playgrounds in the netherlands .
but the limited variability might also be partially due to the fact that all centers in our sample were part of the same coordinating organization , and adhere to central guidelines and policies of that organization . in that respect
it would be interesting to repeat the current study in a broader sample of childcare centers .
this does not solve the problem completely however , as part of the limited variability is probably not only a problem within our sample but in childcare centers in general .
experimental studies would be needed to further examine the influence of the different facilities on children 's activity levels .  
a strong point of the current study is that the environment and physical activity intensity were directly observed and that it did not rely on less valid measures such as self - report .
furthermore , all observations were performed by 2 observers and interobserver reliability indicated substantial agreement . however , although we based the choice for the length of the observation period ( 15 seconds ) on the design of an earlier study using the same instruments , a longer or shorter observation period could also have been chosen , which would possibly have influenced the findings . another point of consideration
is whether the total observed time is representative for a child 's activity during a whole day at childcare .
however , observations were performed in each childcare centre during both a morning and an afternoon , which covers a regular day at childcare in the netherlands ( 9:00 am5:00 pm ) .
finally , children 's behavior could have been influenced by other variables that were not taken into account in this study .
for instance , various social environmental factors such as prompts by peers and staff have been previously linked to children 's physical activity level ( e.g. , ) but were not taken into account in the current study .
childcare organizations can use the findings of the current study to optimize the physical environment to promote children 's physical activity .
not all childcare play facilities that were expected to be physical activity promoting were actually associated with increased activity levels in children . for promoting physical activity , childcare centers should try to optimize indoor space for playing , create outdoor play ground markings , and provide jumping equipment .
finally , the use of various larger facilities such as slides , swings , and sandboxes should be further examined , since they possibly limit children 's activity levels .
these findings need further testing , specifically using experimental research designs .   with regard to future research into environmental influences on physical activity at childcare ,
the current study showed that physical activity facilities are probably better not summarized into general quality measures .
it is , however , important to map the physical environment as completely as possible .
existing instruments ( e.g. , [ 18 , 19 ] ) are very useful for this purpose , although some cultural adaptations might be necessary , depending on the country in which the research is conducted .
the current study examined the influence of physical activity facilities on children 's activity levels at childcare .
many other studies have previously examined the association between the childcare environment and children 's activity levels , applying many different research designs and various focuses [ 16 , 2026 , 32 , 3740 ] . however , these studies have in common that they mostly have a narrow , one - sided view on these environmental influences .
this view mostly incorporates a physical activity stimulating environment as a whole , without further specifying contributes of individual environmental characteristics .
ecological models integrate environmental influences with individual influences and influences from other settings ( e.g. , the home environment ) [ 41 , 42 ] , giving an overview of the broader picture in which the child 's behavior takes place .
we feel that also in the case of childcare , future studies should not only examine the direct influences of the childcare environment , but also the interactive influences of the childcare environment with children 's characteristics ( e.g. , sex , temperament ) and the home environment .
 this study investigated the association between physical activity facilities at childcare ( e.g. , play equipment ) and physical activity of 2- and 3-year olds . 
 observations of physical activity intensity were performed among 175 children at 9 childcare centers in the netherlands , using the osrac - p . 
 the physical activity facilities were assessed for indoors and outdoors separately , using the epao instrument . 
 regular ( single - level ) multivariate and multilevel linear regression analyses examined the association of the facilities and child characteristics ( age and sex ) with children 's activity levels . 
 various physical activity facilities were available in all childcare centers ( e.g. , balls ) . 
 riding toys and a small playing area were associated with lower indoor physical activity levels . 
 outdoor physical activity levels were positively associated with the availability of portable jumping equipment and the presence of a structured track on the playground . 
 portable slides , fixed swinging equipment , and sandboxes were negatively associated with outdoor activity levels . 
 in addition , the 3-year old children were more active outdoors than the 2-year olds . in conclusion , 
 not all physical activity facilities at childcare were indeed positively associated with children 's activity levels . 
 the current findings provide concrete leads for childcare providers regarding which factors they can improve in the physical environment to facilitate children 's physical activity . 
1. Introduction
2. Methods
3. Results
4. Discussion
5. Conclusions
6. Future Directions