Recess as a Setting for Child Development: A Randomized Controlled Trial on Physical Activity, Motor Skills and Social–Emotional Functioning

ABSTRACT

Background

Recess can be beneficial for enhancing physical activity levels, but evidence on broader developmental outcomes remains mixed.

Methods

A randomized controlled trial (21 Dutch primary schools, N = 1154 children, mean age = 9.0 years) evaluated a one‐year recess intervention. Physical activity behavior was measured using accelerometers and observation. Motor skills were assessed with the Athletic Skills Track, and social–emotional functioning through teacher‐ and self‐reports and observations. Implementation fidelity was monitored.

Results

No significant intervention effects were found on physical activity behavior or social–emotional functioning. Motor skills improved for both groups, with greater gains in the control group. Implementation fidelity did not significantly affect results.

Implications for School Health Policy, Practice, and Equity

Implementing standardized intervention programs may not necessarily produce the intended outcomes, possibly requiring more context‐specific strategies. Schools may benefit from practical tools to effectively promote children's physically active play at the playground, considering school‐ and population‐specific characteristics.

Conclusions

This study refines the evidence on recess‐based interventions. The larger gains in motor skills observed in the control group suggest that interventions do not necessarily affect practice as intended, highlighting the importance of considering contextual and methodological factors to better understand what works, for whom, and under which conditions.

Many children fail to meet international physical guidelines of at least 60 min of moderate‐to‐vigorous physical activity (MVPA) per day [1, 2, 3, 4]. These patterns are alarming, because lack of physical activity can negatively affect children's health [3, 5], for instance increasing chances for obesity [6, 7] and cardiovascular disease risk factors [8]. Moreover, physical activity promotes children's motor skills [9, 10, 11, 12] and offers opportunities to develop social skills, such as cooperation, conflict resolution, and emotional regulation [13] having important implications for both motor and social–emotional development [11, 14, 15, 16, 17].

At school, recess provides a unique opportunity for children's physical activity [18], with some researchers suggesting that children should engage in MVPA for at least 40% of recess. Unfortunately, these guidelines are generally not met [19, 20]. Recess interventions hold promise in enhancing physical activity levels [21], with effective strategies being variation in activities, schoolyard markings and different play zones [18, 21, 22, 23]. Particularly, children with the lowest proficiency levels seem to benefit from such interventions, possibly because they have the most room for growth [24, 25, 26].

Given the importance of physical activity for children's physical and social–emotional development, recess interventions, by increasing physical activity, may also improve these outcomes [27]. Although some school‐based interventions have shown promising effects on motor skills or social–emotional functioning, results are mixed [27, 28, 29, 30, 31]. Moreover, few studies have examined whether recess interventions specifically can improve these outcomes and whether changes in physical activity act as an underlying mechanism [31, 32, 33, 34]. Such results are vital for designing school‐based interventions that effectively support both physical and social–emotional development and health. This study examined the effects of a recess intervention on primary school children's physical activity (intensity and variation), and consequently on motor skills and social–emotional functioning. The intervention structured recess through color‐coded playground zones, weekly organized activities, clear behavioral expectations, and support via teacher facilitation and peer coaching. Implementation fidelity was considered, being a crucial determinant of intervention effectiveness [35]. The intervention was expected to increase both the intensity and variation of physical activity, which in turn would improve motor skills and social–emotional functioning, with children being expected to improve their motor skills and social–emotional functioning [10], with stronger effects for children with lower baseline proficiency levels [24, 25, 26]. Potential differences by age and gender were examined, given mixed findings in previous research [4, 20, 32]. Overall, the study aims to advance understanding of how structured recess can support multiple domains of child development and inform school‐based strategies to promote children's health and well‐being in an accessible way.

1. Methods

1.1. Study Design

A cluster randomized controlled trial was implemented, randomly assigning schools to the intervention or control condition. The intervention lasted one school year, while control schools continued their regular program. Children were assessed at baseline and end of the school year.

1.2. Participants

A large, random sample of regular Dutch primary schools was approached via e‐mail, social media, or information letters. In total, 21 regular primary schools participated, located across rural and urban areas (see Figure 1 for the Consort Flowchart). Most schools declined to participate due to workload.

FIGURE 1.

CONSORT flow diagram.

An a priori power analysis in Optimal Design Plus [33] (rho = 0.07 [34, 36], R ² = 0.20 [37], expected effect size = 0.40 [38], cluster size = 55 children, α = 0.05, power = 0.80) indicated a minimum of 18 schools.

In total, 1154 children participated (50.4% boys), of whom 593 in the intervention condition (50.6% boys) and 561 in the control condition (50.3% boys), with a mean age of 9.0 years (SD = 1.3, range = 5.9–13.3 years). The study was approved by the ethics committee of the Faculty of Behavioral and Human Movement Sciences of the Vrije Universiteit Amsterdam (VCWE‐2021‐160). Written informed consent was obtained from legal guardians.

1.3. Outcome Measures

1.3.1. Physical Activity Behavior

1.3.1.1. Intensity

Amount and intensity of physical activity during recess were measured using accelerometers (ActiGraph GT3X+), recording three‐axial at 100 Hz. Data were processed in ActiLife (v7) using a 15‐s epoch classifying activity intensity into percentage of time spent as sedentary, LPA, and MVPA using validated cut‐off points [39].

1.3.1.2. Variation

Variation in physical activity was assessed using activity type and group size (as percentage of recess time) with the System for Observing Children's Activity and Relationships During Play (SOCARP), a validated (r = 0.67) and reliable (interobserver agreement 88%–90%) measure of children's recess physical activity [40]. SOCARP captures four domains:: intensity, activity type, group size, and social interactions. Observations were conducted in 10‐s intervals, followed by 10‐s recording periods, for a total of 24 intervals per child per recess. Inter‐rater reliability was assessed by double coding 29.3% of the sample, being excellent for activity intensity (ICC = 0.84) and group size (ICC = 0.95), good for activity type (ICC = 0.88), and moderate for social interactions (ICC = 0.73). In total, 577 children (50%) were observed at baseline and 589 (51%) at follow‐up, with 463 (40.1%) observed at both time points.

1.3.2. Social–Emotional Functioning

1.3.2.1. Social–Emotional Problems and Prosocial Behavior

A Dutch translation of the teacher‐report version of the Strengths and Difficulties Questionnaire (SDQ) measured social–emotional problems and prosocial behavior [41, 42]. The SDQ contains 25 items rated on a 3‐point scale (not true, somewhat true, certainly true) across five subscales: hyperactivity/inattention, emotional symptoms, conduct problems, peer problems, and prosocial behavior. Teachers rated children's behavior over the past 6 months, an example item being “Considerate of other people's feelings.” Based on PCA results (see below), the first four subscales were summed to form a social–emotional problems score (range = 0–40), while prosocial behavior was analyzed separately (range = 0–10). The SDQ has demonstrated good validity and reliability internationally [41] and in Dutch samples [43], with internal consistency ranging from acceptable to good (α = 0.74–0.87). In the current study, reliability was good (α = 0.89 at baseline).

1.3.2.2. Social Self‐Efficacy

The social subscale of the Self‐Efficacy Questionnaire for Children (SEQ‐C) was used to assess social self‐efficacy [44], comprising seven items describing social situations (e.g., “I can become friends with other children of my age”) rated on a 5‐point Likert scale ranging from not at all (1) to very well (5). The SEQ‐C has demonstrated good validity and reliability (α = 0.85–.88 [44]) and has been successfully used in Dutch primary school settings [45]. In the present study, internal consistency of the social self‐efficacy subscale was acceptable (α = 0.69).

1.3.2.3. Classroom Climate

The Classroom Peer Context Questionnaire (CPCQ) assessed classroom‐climate [46]. The CPCQ consists of 20 items across five subscales: comfort, cooperation, conflict, cohesion, and isolation, rated on a 5‐point Likert scale ranging from not at all true (1) to completely true (5). An example item is “In this class, I belong to the group.” The CPCQ has demonstrated good validity and reliability (α > 0.70), also in the current sample (α = 0.88).

1.3.2.4. Positive and Negative Interactions During Recess

As indicators of positive and negative interactions during recess, interactions (measured in percentage of recess time) were observed using the SOCARP [40], described above.

1.3.3. Motor Skills

Children's motor skills were assessed using the Athletic Skills Track [47, 48, 49]. Age‐appropriate tracks (AST‐II for ages 6–9; AST‐III for ages 9–12) comprised a series of fundamental motor skills (e.g., balancing, hopping) that had to be completed as quickly and accurately as possible. Incorrectly performed skills had to be repated while the timer continued, capturing both speed and accuracy. Completion time was converted into an age‐ and gender‐adjusted Motor Quotient (MQ). The AST has demonstrated good reliability (ICC = 0.80–0.80; Cronbach's α > 0.70) and validity [48, 49, 50].

1.3.3.1. Implementation Fidelity

Implementation fidelity was assessed using two indicators: dose and adherence. Dose was defined as the total number of intervention implementation days, weighted by delivery frequency (once per week = 1, twice per week = 2). Adherence reflected the extent to which the intervention was delivered as intended and was assessed by two researchers based on notes from three school meetings per school, documenting progress and modifications during the intervention. Key intervention components were coded, that is, the use of junior coaches, the use of the (online) playground program, and teachers' active involvement on the playground, each rated on a three‐point scale (1 = not implemented, 2 = occasionally implemented, and 3 = implemented; see Appendix 2 in Supporting Information). A total adherence score was calculated as the mean of these indicators. Implementation fidelity was consequently calculated as the ratio of dose to adherence, with lower scores indicating lower fidelity (see Table 1 for implementation fidelity scores per school).

TABLE 1.

Implementation fidelity (dose in days; adherence to the intervention protocol ^b ; and implementation fidelity score calculated as dose x adherence) for intervention schools ^a .

	Dose (days)	Adherence b	Implementation fidelity
School 1	42	1	42
School 2	43	1.3	32.3
School 3	42	1.3	31.5
School 4	48	1.7	28.8
School 5	48	1.7	28.8
School 6	48	1.7	28.8
School 7	39	1.7	23.4
School 8	25	2.3	10.7
School 9	25	2.3	10.7
School 10	0	3	0

^a Schools are listed in a random order.

^b Adherence was scored between 1 and 3, where 1 = high adherence and 3 = low adherence.

1.4. The Intervention

The school‐based intervention (Beweeg Wijs) aims to increase children's physical activity and active play during recess. The program structures the playground into five color‐coded zones using colored ground markings, each linked to specific types of play and behavioral expectations. The blue zone includes individually performed activities aimed at skill improvement (e.g., wall tennis against a wall, juggling, rope skipping). The yellow zone includes turn‐taking activities, such as hopscotch, cycling, or hurdle‐running. The orange zone focuses on shared activities requiring children to maintain the game collectively, such as., frisbee or badminton. The green zone includes cooperative play such as parachute play or rope jumping in teams. The red zone consists of competitive games, such as football or relay races.

Weekly activity plans are prepared via an online platform, specifying activities per color zone for that week. On intervention days, children receive a brief instruction at the playground, led by a supervisor (school staff or external professional), introducing that week's activities. Implementation starts at 1 day per week and increases to 2 days per week halfway through the intervention. During recess, children can choose between organized activities and free play. Teachers facilitate and support activities, and junior coaches (older children) assist by explaining and guiding activities.

1.5. Procedure

All measurements were conducted at the children's schools by trained research assistants under the supervision of a research coordinator. Assistants completed a four‐hour training session on study protocols and practiced test administration in pairs, having to achieve > 80% inter‐rater agreement for observational measures before data collection began.

Physical activity was assessed during morning and lunch recess on two separate days (four recess periods per child). Accelerometers were placed on the right hip before the first recess and removed after the second, while observational measures were collected concurrently using standardized protocols. Regular recess durations were maintained, ranging from 10 to 45 min across schools. Motor competence was assessed during one physical education lesson, in which children individually completed the Athletic Skills Track. After three practice trials, a timed fourth trial was used as an outcome measure. Child questionnaires were completed in children's classrooms, with assistance from research assistants. For younger children, questions were read aloud. Teacher questionnaires were completed independently within a two‐week window in the same period. Children who were absent completed questionnaires later, but within 2 weeks, with teacher support.

1.6. Data Analysis

SPSS Statistics 29 (IBM Corp, 2021) was used for data preparation, data screening, and preliminary analyses. For multilevel analyses, JASP software was used [51]. Statistical significance was set at p < 0.05.

A principal component analysis (PCA) with promax rotation was performed in SPSS to reduce the number of social–emotional functioning outcomes (CPCQ, SEQ‐C, and SDQ questionnaires and the degree of observed positive and negative interaction during recess). The Kaiser‐Meyer‐Olkin measure indicated an acceptable level of sampling adequacy (0.76). Bartlett's test of sphericity was significant, χ ²(45) = 1469.87, p < 0.001, indicating that the data were suitable for factor analysis. The analysis yielded three components with eigenvalues greater than one, together explaining 61.1% of the total variance. The first component reflected a positive classroom climate, with high charges for cooperation, cohesion, and comfort, and negative charges for conflict and isolation (33.2%). The second component represented social–emotional behavior, with a negative charge for prosocial behavior and a positive charge for behavioral difficulties (15.3%). The third component concerned recess behavior, in which positive behavior charged negatively and conflicts positively (12.5%).

To examine the effectiveness of the intervention, linear mixed models were fitted for physical activity behavior (percentage of sedentary time, percentage of time spent in MVPA, percentage of time playing in large groups, percentage of time engaged in active games), three components of social–emotional functioning (positive classroom climate, social–emotional behavior and recess behavior), and motor skills. Empty models were initially estimated at four levels: measurement occasion, participants, class, and school. The class or school level was excluded if its intraclass correlation coefficient (ICC) was ≤ 0.02. Linear mixed models were then constructed with the retained levels. Five sequential linear mixed models were fitted. The first model included condition as sole predictor. In the second model, child‐level covariates (grade, age, and gender) were added. The third model included school‐level covariates: school size and school deprivation scores [52]. In the fourth model, the interaction between condition and baseline scores for motor skills and social–emotional functioning was added. Finally, the fifth model included implementation fidelity.

A mediation analysis was performed to test whether the effects of the intervention on motor skills and social–emotional functioning were mediated by changes in physical activity.

2. Results

Descriptive statistics are presented in Table 2. Independent t‐tests revealed no significant difference between intervention and control groups at baseline for physical activity intensity, social self‐efficacy, classroom cooperation, conflict, isolation, and comfort (CPCQ), prosocial behavior (SDQ), and positive and negative interactions during recess (SOCARP).

TABLE 2.

Descriptives statistics of all outcome measures.

		Baseline		Posttest
		Control mean (SD)	Intervention mean (SD)	Control mean (SD)	Intervention mean (SD)
Physical activity behavior
Intensity (% of recess)	SED	21.0% (11.1%)	22.0% (12.6%)	21.4% (12.3%)	21.1% (11.9%)
	MVPA	34.5% (14.1%)	34.3% (13.8%)	33.1% (13.0%)	33.6% (14.7%)
Playing in large group (% of recess)		12.3% (29.2%)	17.9% (33.6%)	20.7% (35.9%)	21.5% (37.2%)
Playing active games (% of recess)		28.6% (37.4%)	21.7% (32.3%)	22.9% (35.2%)	18.7% (31.0%)
Social–emotional functioning
SEQ‐C (mean score)		3.7 (0.6)	3.7 (0.7)	3.7 (0.7)	3.8 (0.6)
CPCQ (mean score)	Cooperation	3.9 (0.8)	4.1 (0.8)	4.0 (0.7)	4.0 (0.8)
	Conflict	2.4 (1.0)	2.3 (1.0)	2.5 (0.9)	2.3 (1.0)
	Cohesion	3.5 (1.0)	3.6 (0.9)	3.5 (0.9)	3.5 (0.9)
	Isolation	2.2 (1.0)	2.2 (0.9)	2.1 (0.9)	2.0 (0.9)
	Comfort	4.3 (0.8)	4.3 (0.8)	4.3 (0.9)	4.4 (0.8)
SDQ (sum score)	Pro social	8.5 (1.9)	7.8 (2.3)	8.7 (1.8)	8.2 (2.0)
	Total problems	6.2 (5.7)	6.5 (5.8)	6.0 (5.4)	6.0 (5.8)
Recess behavior (% of recess)	Positive	34.9 (27.5)	38.4 (29.3)	38.8 (23.6)	39.9 (22.7)
	Negative	10.2 (15.5)	10.0 (16.9)	4.1 (7.9)	4.0 (7.1)
Motor skills
MQ score		87.4 (18.2)	92.0 (18.5)	95.0 (35.6)	98.5 (20.4)

Abbreviations: CPCQ, Classroom Peer Context Questionnaire; MQ score, Motor Quotient score; MVPA, moderate‐to‐vigorous physical activity; SDQ, Strenghts‐ and Difficulties Questionnaire; SED, Sedentary behavior; SEQ‐C, Self‐Efficacy Questionnaire for Children.

For baseline physical activity variation, the intervention group played significantly more in large groups (M = 17.90, SD = 33.64) than the control group (M = 12.31, SD = 29.24), t(575) = 2.21, p = 0.034, also playing significantly fewer active games (M = 21.70, SD = 32.26) than the control group (M = 28.64, SD = 37.43), t(575) = −2.39, p = 0.017. The intervention group (M = 91.98, SD = 18.46) scored significantly higher on baseline motor skills than the control group (M = 87.39, SD = 18.18), t(1080) = 4.12, p < 0.001. Lastly, the intervention group scored significantly higher on baseline classroom cohesion (M = 3.620, SD = 0.88) than the control group (M = 3.46, SD = 0.98), t(2.748) = 7.811, p = 0.005., and significantly lower on social–emotional problems (M = 7.82, SD = 2.32) than the control group (M = 8.46, SD = 1.91), t(−5.190) = 20.735, p < 0.001. These baseline differences were accounted for by including them as covariates in the analyses.

The full set of results is presented in (Appendix 1 in Supporting Information). Below, we focus on differential effects of the intervention, reflected in the interaction between time and condition. The simplest model is presented, unless one of the added variables in the subsequent models was significant.

2.1. Physical Activity Behavior

No significant interaction effect between time and condition was found for sedentary behavior (F(1, 20.99) < 0.001; p = 0.999), MPVA (F(1, 18.88) = 0.101; p = 0.754), playing in large groups (F(1, 15.80) = 0.568; p = 0.462) and playing active games (F(1, 24.25) = 0.026; p = 0.873), suggesting that the intervention did not have a significant effect on children's physical activity behavior during recess.

2.2. Social–Emotional Functioning

No interaction effect was found for the components positive classroom climate (F(1, 91.01) = 0.061, p = 0.806), social–emotional behavior (F(1, 19.08) = 0.337, p = 0.568), or recess behavior (F(1, 21.60) = 1.266, p = 0.273), suggesting that the intervention did not have a significant effect on children's social–emotional functioning.

2.3. Motor Skills

A significant interaction effect between time and condition was found for motor skills (F(1, 21.68) = 5430; p = 0.030), indicating that the increase in motor skills was greater in the control group than in the intervention group.

3. Discussion

This study examined the effects of a recess intervention on children's physical activity behavior, motor skills, and social–emotional functioning. In contrast to our hypotheses, no significant effects of the intervention were found on physical activity behavior or social–emotional functioning. Surprisingly, motor skills improved to a larger extent in the control group than in the intervention group. Effects did not differ depending on implementation fidelity, child‐level and school‐level characteristics, or children's initial functioning. As no changes were found in physical activity behavior, we could not support our hypothesis that positive effects on motor skills and social–emotional functioning would be brought about by changes in physical activity.

3.1. Effectiveness of Recess‐Based Physical Activity Interventions

Several explanations may account for the null results. First, the intervention dose may have been insufficient, as the intervention was shortened from its intended two‐year duration to 1 year for study feasibility. Meaningful behavioral changes, particularly in motor skills and social–emotional functioning, may require more time [53, 54, 55]. Conversely, the intervention may have been too long. Positive effects reported in previous studies of similar interventions [56, 57] may partly reflect a “novelty effect” [58], whereby the introduction of a new element temporarily increases engagement and performance. Supporting this interpretation, longer recess interventions have been associated with declines in MVPA [59, 60], or with initial increases in physical activity that diminished over time and were accompanied by more sedentary behavior [37]. Further research is needed to determine the optimal intervention dose for achieving sustainable positive effects. Relatedly, the intervention was implemented during relatively short recess periods (10–45 min), constraining available time for physical activity. Compared with typical playground activities, many intervention activities required additional organization, including time for choosing activities and repeating instructions when new children joined ongoing activities. Consequently, activities may have started later or been interrupted, reducing opportunities for active engagement and skill development. Over time, as children become more familiar with the activities, the organizational time may decrease, leaving more time for physical activity, increasing the potential for promoting developmental outcomes [61]. This again highlights the importance of intervention dose and timing. Furthermore, differences between schools in how staff supervise and implement the intervention may influence the extent to which children benefit from it [35]. Although our results suggest that implementation fidelity did not play a significant role, our implementation measure contained a single score. A more detailed analysis may have identified specific implementation components that contribute to intervention effectiveness. Combining quantitative outcomes with qualitative accounts of user experiences could provide deeper insight into how schools can implement interventions effectively and feasibly [62, 63].

Alternatively, the intervention may have been too directive limiting children's autonomy and thereby reducing intrinsic motivation [64], a key facilitator of recess physical activity [65]. Children generally perceive the school playground as an environment in which they can make their own choices, in contrast to the teacher‐controlled classroom setting [66]. The adult‐led activities in our intervention may have constrained children's perceived autonomy. However, previous research indicates that structured adult‐led activities can also promote physically active play during recess [61, 67], suggesting that children may differ in their preferences for external guidance [66]. Importantly, our intervention also incorporated autonomy‐supportive elements, by providing a variety of play activities from which children could choose, an aspect that children themselves value [66, 68, 69]. Further research is needed to clarify how need support and motivation influence effectiveness of recess‐based interventions, and to explore potential inter‐individual differences herein [66].

3.2. Changes in Motor Skill Development

Unexpectedly, children in the control group improved their motor skills to a larger extent than children in the intervention group. As the control group had significantly lower baseline scores, this may partly reflect greater room for improvement. Yet, other explanations should also be considered. The intervention targets motor skills as a secondary outcome, expected to improve indirectly from changes in physical activity (intensity and variation). As no changes in activity patterns were observed in either group, it is surprising that the control group improved more on motor skills than the intervention group. Consequently, it can be questioned whether the expected mechanism of change holds.

Alternative mechanisms of change may, first, relate to the cognitive load inherent in many intervention activities, often involving multiple (social) rules, thereby placing additional demands on children's working memory. This increased cognitive load may have limited the attentional resources available for motor skill execution and development [70, 71] particularly for lower‐skilled children who tend to have lower working memory capacity [72, 73].

Second, children's perceived motor competence may have played a role. The novel activities introduced in the intervention may have led children in the intervention group to feel less competent, as they may have found unfamiliar activities more challenging than those they typically engage in [74]. This reduced sense of competence may, in turn, have negatively affected their actual motor skill performance [75].

Several methodological factors may also help explain the unexpected results for motor skill outcomes. First, the test used has lower discriminative ability among higher‐skilled children [48], meaning it may be better suited to capturing improvements within the lower‐skilled group. Furthermore, the skills assessed by the test may not fully align with those practiced during the intervention activities. The test primarily measures gross fundamental motor skills (e.g., balancing, hopping), whereas motor competence encompasses a broader range of skills, with performance varying across tasks [76, 77]. For future research, it would be valuable to examine motor domains separately to identify potential differential effects.

3.3. Strengths and Limitations

Strengths of this study include the large sample and the objective and valid measurement of children's physical activity during recess [4, 78]. Also, we accounted for implementation fidelity (although providing limited detail), which is often overlooked in physical activity intervention studies [35].

A limitation of this study is the potential for Hawthorne effects [79], whereby children may have altered their behavior because they wore accelerometers and were being observed. However, research has shown that wearing accelerometers does not necessarily affect activity patterns [80]. Moreover, children wore the devices on two school days, and they were attached at the start of the school day rather than immediately before recess, likely reducing awareness of monitoring.

Because no effects were found on physical activity behavior, we could not examine its role as a mechanism underlying improvement in motor skills and social–emotional functioning. Nevertheless, understanding this relationship remains important, as it can advance theoretical models of how movement opportunities support children's overall development and provide practical guidance for intervention developers and educators. Such insights may clarify whether increasing physical activity is a necessary condition for fostering improvements in motor skills and social–emotional functioning.

3.4. Implications for School Health Policy, Practice, and Equity

Our findings highlight the challenges of evaluating controlled interventions in routine educational practice, showing that participants' experiences do not necessarily align with quantitative outcomes. Apart from the larger gain in motor skills observed in the control group, the intervention did not produce measurable effects. Nevertheless, schools, teachers, and children reported positive experiences, consistent with positive changes noted in previous research on this intervention [81]. This suggest that the added value of educational interventions may be difficult to capture quantitatively in real‐world settings and may be expressed more strongly in daily practical experience than in the measured developmental outcomes. Outcomes are likely influenced by contextual and methodological factors, including intervention duration and/or dose, staff training and supervision, and decisions in study design (e.g., measurement instruments or assessment timing).

Importantly, the intervention offers starting points for structuring recess play and creating meaningful physical activity opportunities. However, children may require guidance to engage in such activities, as they may struggle to do so independently [67, 68, 69]. While interventions can be valuable tools, our findings suggest that they are not inherently effective and may even have unintended outcomes. These insights contribute to a better understanding of how recess‐based interventions may (or may not) affect children's development and can inform future research into the conditions and mechanisms underlying their effectiveness. Such work is needed to help schools effectively promote children's physical activity, for example in the form of implementation guidelines or practical, easy‐to‐implement strategies.

4. Conclusion

In conclusion, no effects of the recess intervention were found on children's recess physical activity, motor skills, and social–emotional functioning, suggesting that structured and unstructured recess play may be equally beneficial for children's development. Unexpectedly, motor skills improved more in the control group, suggesting that recess‐based interventions are not inherently effective. Further research is needed to understand when, why, and how recess‐based interventions can support children's development to ensure that all children can benefit from recess.

Funding

This work was supported by Nationaal Regieorgaan Onderwijsonderzoek, 202122.

Ethics Statement

The study was approved by the ethics committee of the Faculty of Behavioral and Human Movement Sciences of the Vrije Universiteit Amsterdam (VCWE‐2021‐160).

Consent

Written informed consent was provided for all children by their legal guardians.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Appendix 1 Full results of intervention effects.

Table 1a Full set of results for linear mixed models.

Table 2a Scoring of adherence to the intervention protocol for the intervention schools.

Appendix 2 Scoring of adherence to the intervention protocol.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.