The early years are a prime time for social–emotional development. Throughout the preschool years, children improve their social–emotional competencies, such as empathizing with others’ feelings, adapting behaviors, thoughts, and emotions, communicating their emotions and mental states, and cooperating and socializing with peers. Social–emotional competence has critical implications for children’s adjustment and success (Shonkoff and Phillips, 2000), such that it is widely recognized as a central goal of preschool education and a target of several intervention programs.

Although most intervention programs have been implemented indoors, the potential of outdoor learning dates to Aristotle and Plato. Indeed, the importance of the outdoors for children’s development is highlighted by the term kindergarten (or garden of children) and is central to the educational theories of recognized pedagogues such as Rousseau, Froebel, or Pestalozzi (Allen, 2017). The outdoors is a highly stimulating setting where emotions can run high, and children feel freer to move, experiment and modulate the environment and their behavior (Veiga et al., 2020). A recent systematic review showed that natural environments facilitate children’s positive relationships and socially adaptive behaviors (Mygind et al., 2021). Moreover, contact with natural elements has been established to have a calming effect, reducing stress and improving mental health (Tillmann et al., 2018). Specifically, concerning outdoor-friendly early childhood environments, the systematic review of Johnstone et al. (2022) showed the benefits for children’s social–emotional competence, particularly self-regulation and relationship skills.

With so few years under their belts, preschoolers are still learning to inhabit their bodies. Actually, it is by engaging their bodies in doing, moving, acting, and interacting that children acquire knowledge and master their competencies. Indeed, play, dance, relaxation, and other body-oriented approaches have been increasingly implemented in early childhood education and are known to effectively promote preschoolers’ social–emotional competence (Dias Rodrigues et al., 2022a,b). Body-oriented interventions are supported by the intrinsic relationship between motion and emotion, integrating both sides in a balance of sensing and moving. As bodily sensations, bodily postures, gestures, and expressions are inherent components of the emotional experience, accessing such somatic information is critical to one’s identity and social–emotional development (Fuchs and Koch, 2014). Nonetheless, a recent systematic review (Dias Rodrigues et al., 2022b) focused on the effects of body-oriented interventions implemented in early-childhood education settings, showed inconsistent findings regarding the benefits of these interventions on self-regulation. Such inconsistency was related to differences in the dosage of the interventions, suggesting that a higher frequency is needed to improve self-regulation. Concerning relationship skills, there is moderate evidence for the improvements of body-oriented interventions on preschoolers’ empathy and social interaction, and limited evidence regarding the improvements in social cooperation (Dias Rodrigues et al., 2022b).

The most used body-oriented approach to improve preschoolers’ social–emotional competence is play (Dias Rodrigues et al., 2022a,b). Regarding play-based interventions, research reveals moderate evidence for improvements in empathy and social interaction, limited evidence for increased social cooperation and contradictory evidence for self-regulation (Dias Rodrigues et al., 2022a). It has been speculated that the type of play facilitated by the intervention might have a critical role and that physical play (particularly, exercise play) might be particularly beneficial concerning self-regulation (Dias Rodrigues et al., 2022a). Indeed, physical play has been argued to give preschoolers an important opportunity to feel their own bodily states, which are a central part of the emotional experience. Such opportunity is crucial for children to become aware of the relationship between their own bodily states and emotions, therefore promoting self-awareness and regulation (Veiga et al., 2022). Moreover, research has shown that exercise play, mainly when engaged with peers, is related to emotion understanding, emotion regulation and social competence (Lindsey and Colwell, 2013; Veiga et al., 2017).

Interventions based on relaxation have been also implemented in preschools. Contrary to play interventions, relaxation involves a more pronounced interoceptive approach, with a specific focus on body awareness and regulation which paves the way to self-awareness and regulation (Veiga, 2022). Despite the recent popularity of mindfulness (Flook et al., 2015), other approaches have also been implemented in preschools, such as breathing exercises or progressive muscle relaxation (Murray et al., 2018). However, studies focused on this type of body-oriented intervention are still scarce and with low methodological quality (Dias Rodrigues et al., 2022a). Although a recent systematic review showed moderate evidence that relaxation intervention does not improve self-regulation, the authors hypothesized that such lack of positive outcomes could be related to the short duration of the sessions (11–25 min) (Dias Rodrigues et al., 2022a). No studies have yet examined the effects of relaxation on preschoolers’ relationship skills.

Body-oriented interventions combining play and relaxation are scarce. To the best of our knowledge only one study has combined both approaches, however the intervention involved an externally-oriented type of play (i.e., loose parts play) and a relaxation moment, which was implemented indoors. Besides, the intervention had a short duration (5-day), and the effects on self-regulation and relationship skills were not examined (Lee et al., 2020).

Acknowledging the important role of exercise play and relaxation for social–emotional development, OUT to IN, a body-oriented intervention program, combining both approaches was designed to improve preschoolers’ social–emotional competence. OUT to IN is based on embodiment theory (e.g., Fuchs and Koch, 2014), aiming to help preschoolers enter a sensing, reflective and affective mode. Hence, bodily activities, i.e., exercise play and relaxation, are structured and facilitated in order to give children opportunities to integrate bodily (interoceptive and proprioceptive) feedback, to reflect on it, and express these corporeal experiences, verbally and non-verbally. Between activities, children are asked to sense their own body, and become aware of their bodily states (e.g., heart rate, temperature, muscle tone, breathing). Considering the above-mentioned potential of the outdoors for social–emotional well-being, the program was designed to be implemented outdoors.

The main purpose of this study was to examine the effects of OUT to IN on preschoolers’ self-regulation and relationship skills. More specifically, it was hypothesized that self-regulation, empathy, cooperation, sociability, and communication would benefit from a 10-week (20 sessions) body-oriented intervention which combines exercise play, relaxation, and symbolization activities.

As shown in Tables 2, 3, there were no statistical differences between groups at baseline, except for empathy as rated by preschool teachers, which was higher for the CG compared to the OUT to IN Group (U = 4407.5; p = 0,045).

Several within- and between-group differences were found for self-regulation (Table 2). Significant improvements were observed after the 10-week intervention for the OUT to IN Group in Day and Night scores (49.4%, p < 0.001) and HTKS scores (165%, p < 0.001). No significant pre-post differences were found for the CG. Mann–Whitney test analysis on change scores showed significant pre-post differences between groups in the Day and Night task (U = 3014.5; p < 0.001) and the HTKS task (U = 1,663; p < 0.001), yielding a positive impact of the intervention. Large effect sizes were found for Day and Night (η² = 0.142) and HTKS (η² = 0.331).

Table 3 shows the results on relationship skills. Regarding within-group results, after 10 weeks children from the OUT to IN Group had higher scores on empathy (2.75%; p = 0.008), cooperation (2.13%, p = 0.019), and sociability (3.22%, p = 0.008), rated by parents, and on empathy (5.75%, p < 0.001) cooperation (2.89%, p = 0.003), and sociability (5.35%, p < 0.001), rated by teachers and had lower scores on emotion communication, as rated by parents (−5.36%, p = 0.002) Moreover, after the 10-week intervention period, children from the CG had lower scores on emotion communication, as rated by parents (−5.24%, p = 0.007), and on empathy (−6.38%, p < 0.001), as rated by preschool teachers.

Mann–Whitney test analysis on change scores showed significant pre-post differences between groups in empathy (U = 2,624; p < 0.001), cooperation (U = 4,028; p = 0.004), and sociability (U = 3478.5; p < 0.001) as assessed by the preschool teachers. A small effect size (η² = 0.012) was found for empathy as rated by parents. Regarding preschool teachers’ assessments, small, medium and large effect sizes were found for cooperation (η² = 0.036), sociability (η² = 0.078), and empathy (η² = 0.172), respectively.

Body-oriented interventions and outdoor time seem to benefit preschoolers’ social–emotional development, a foundation for mental health. We investigated the effectiveness of OUT to IN, a body-oriented intervention program for preschoolers, combining physical play and relaxation activities, that was implemented in the kindergarten outdoors. The findings of the present study suggest that OUT to IN, effectively promotes preschoolers’ social–emotional competence. In particular, OUT to IN showed to increase self-regulation, empathy, cooperation, and sociability. The mostly large effect sizes of these increases suggest the effectiveness of OUT to IN in enhancing preschool children’s self-regulation and relationship skills. To the best of our knowledge, this is the first study to examine the effects of a body-oriented program implemented outdoors on preschoolers’ social–emotional competence.

OUT to IN sessions combined a sequence of exercise play and playful relaxation. Both play and relaxation, give children opportunities to feel and become aware of their bodies, either in movement or stillness (Veiga et al., 2022). Several theories have emphasized the critical role of perceiving bodily states (e.g., Damasio, 1994; Barsalou et al., 2007; Niedenthal, 2007; Fuchs and Koch, 2014) for social–emotional development. Indeed, such bodily awareness is an important component of the emotional experience and seems to facilitate self-regulation (Barrett et al., 2001; Füstös et al., 2013). Besides, both body-oriented approaches (i.e., play and relaxation) involve controlling bodies and mind, particularly by suppressing or countermanding movement and thoughts, therefore stimulating self-regulation. It is important to note that previous studies (Flook et al., 2015; Murray et al., 2018) that implemented relaxation intervention in early-childhood education settings did not show improvements in preschoolers’ self-regulation. However, these studies used sedentary/passive relaxation methods, such as progressive muscle relaxation (Murray et al., 2018) or mindfulness (Flook et al., 2015). Considering that children at such a young age should not be sedentary for extended periods (World Health Organization, 2019) and prefer intermittent type (passive/active) activity (Timmons et al., 2007), such inconsistent findings previously reported (Dias Rodrigues et al., 2022a) might suggest the importance of using physically active approaches, such as exercise play, and active relaxation when aiming to facilitate preschoolers’ self-regulation. Besides, the outdoor environment is also known as a facilitator of physical activity and self-regulation (Tillmann et al., 2018; Johnstone et al., 2022). In fact, the other known study that implemented a combined play-relaxation program (Lee et al., 2020) used more sedentary forms of play (i.e., loose parts play) and relaxation (i.e., mindfulness), that was experienced indoors.

It is important to note that, in line with other previous studies (Solomon et al., 2018; Richard et al., 2019) that also used play to improve preschoolers’ social–emotional competence, OUT to IN did not effectively decrease externalizing behaviors. While those other studies (Solomon et al., 2018; Richard et al., 2019) used role play, OUT to IN used exercise play. This more active form of play had been hypothesized by a previous systematic review (Dias Rodrigues et al., 2022a) to be important to help children learn to regulate their impulses. However, our findings did not confirm this hypothesis. Possibly, only an intervention based on rough-and-tumble play, which involves physical contact with peers, sharing the winning and losing, and more intense arousal, can help preschoolers learn to regulate their behavior. Although previous studies with older children (Carraro et al., 2014; Carraro and Gobbi, 2018) point in this direction, no study has yet examined the effects of an intervention based on rough-and-tumble play on preschoolers’ externalizing behaviors.

Nonetheless, our findings show that OUT to IN effectively improves relationship skills, such as empathy, cooperation, and sociability, which is in line with a previous systematic review that showed moderate evidence for the positive effects of play-based interventions on empathy and social interactions (Dias Rodrigues et al., 2022a). According to the authors, over and above the type of play, the social level of the intervention is the most critical component for the improvement of relationship skills. In fact, it should be emphasized that OUT to IN sessions, are carried out with the whole group of children, and involve a progression in terms of the frequency and complexity of social interactions. While the first sessions are focused on the child’s self-awareness, throughout the program there is a progressive approach to the others, implicating the empathic observation and response to the other, cooperation and problem solving.

Concerning relationship skills rated by preschool teachers, it is also important to note that while children who participated in the OUT to IN intervention increased their competencies after the 10-week period, children in the inactive control group decreased their competencies. These findings denote the importance of an intervention program for setting children on a positive trajectory for ongoing development. OUT to IN seems to protect preschoolers, uplifting them in their social relationships, which are known to be critical for their health and well-being (Goswami, 2012). The non-significant changes in relationship skills rated by parents might be related to the fact that parents do not have as many opportunities to observe their children in social contexts as preschool teachers do, limiting their appreciation of relationship skills and their sensitivity to changes in this domain (Huber et al., 2019).

Finally, our findings show that parents reported a decrease in emotion communication. Every OUT to IN session ended with a moment of symbolization when children were invited and guided to reflect on the sensations felt during exercise play and relaxation activities. Despite this specific moment to elaborate and express themselves through expressive mediators (e.g., paint, dance) such non-verbal approach might not have been enough to improve emotion communication. Moreover, although the outdoor context particularly favors body expressiveness, it poses some constraints (e.g., acoustic, intimacy) to emotional communication. The improvement of emotion communication would possibly require a calmer moment (indoors) after the session, where children could give words to their gestures, poses, and expressions.

The role of preschool teachers on the success of the program should also be acknowledged. As other studies showed (Reder et al., 2000; Justo, 2008), adults’ social–emotional competencies are critical for children’s social–emotional development. Indeed, before the beginning of the intervention, preschool teachers participated in a 25-hour training that increased their knowledge and competence regarding preschoolers’ social–emotional competence and the role of body-oriented approaches and outdoor time for social–emotional well-being. Besides, preschool teachers engaged in relaxation sessions, during the same period of children’s intervention. Such empowerment of preschool teachers’ knowledge and competence on the social–emotional domain, might have been important for the success of the intervention with children. Future studies would benefit from a planned examination of which specific components (children’s intervention, preschool teachers’ intervention, or combined interventions) of the program contribute to children’s outcomes. Moreover, future studies should also add a parent component to the intervention, as recent research indicates a stronger impact of children intervention when combined with parents’ intervention (Neville et al., 2013).

OUT to IN showed to be an effective body-oriented intervention program in improving children’s self-regulation and relationship skills, which are recognized foundations for mental health and well-being. Nonetheless, it is important to note that this study has some limitations, such a lack of an active control group. Moreover, although the OUT to IN group and the control group were similar at most baseline measures, and group allocation was randomized, children were nested within classrooms. Thus, future research could use randomized control trials with random assignment at the individual participant level. Also, future studies should combine questionnaires with observational methods in order to have a more ecological assessment of social-relationship skills. Finally, further studies must include a post-intervention follow-up in their design to evaluate the long-term effectiveness of the OUT to IN intervention in self-regulation and relationship skills.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by University of Évora Ethics Committee. The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin.

GV and JM contributed to the design and conception of this study. GV, DG, and GDS cautiously designed the intervention program. GV and CP supervised the implementation of the study. DG collected data, which was analyzed by GV, DG, and JM. GV wrote the first draft of the manuscript. All authors contributed to manuscript revision, read, and approved the submitted version.

This work was co-financed by the Calouste Gulbenkian Foundation’s Knowledge Academies program and by the University of Évora.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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