According to SDT, levels of self-determined motivation are shaped by the satisfaction or frustration of three essential, universal, and innate psychological needs—autonomy, competence, and relatedness (Deci and Ryan, 2000). Specifically, the sub-theory of Relationship Motivation Theory (RMT; Deci and Ryan, 2014) postulates the existence of a basic psychological need for relatedness, which drives individuals to seek and strengthen affective bonds. RMT asserts that “establishing and maintaining close relationships are among the most important and autonomously pursued aspects of people’s lives” (Deci and Ryan, 2014, p. 53). This need must be supported by the social environment (e.g., teachers, families, and peers) to generate positive effects in affective, behavioral, and cognitive domains (Vasconcellos et al., 2020; White et al., 2021; Leo et al., 2023b).

In the educational context, teachers play a crucial role in fostering classroom-relatedness. Specifically, PE teachers can use relatedness-supportive and/or relatedness-thwarting strategies (Ahmadi et al., 2023). In the first case, teachers who foster relatedness create a warm environment that facilitates positive communicative exchanges between students and teachers, as well as among students, promoting harmonious group integration (i.e., relatedness support; Leo et al., 2023e). Conversely, teachers who thwart this need create a distant, cold, and unresponsive classroom atmosphere, adopting behaviors of rejection and exclusion toward students, as well as fostering poor relationships among them (i.e., relatedness thwarting; Leo et al., 2023e). In this regard, numerous correlational studies based on SDT (Deci and Ryan, 2000) have found a positive relationship between PE teachers’ relatedness-supportive behaviors and students’ relatedness satisfaction in PE, as well as between PE teachers’ relatedness-thwarting behaviors and students’ relatedness frustration (Vasconcellos et al., 2020). In turn, relatedness satisfaction, understood as the experience of feeling connected, valued, and cared for in one’s social environment, has been positively related to autonomous motivation and affective (e.g., enjoyment), behavioral (e.g., engagement), and cognitive (e.g., academic performance) domains, while relatedness frustration, which refers to the perception of being excluded, rejected, or ignored in interpersonal contexts, has been positively associated with problematic relationships (i.e., affective domain), disruptive behaviors (i.e., behavioral domain) and low academic performance (i.e., cognitive domain; Leo et al., 2023e; Sparks et al., 2017; Vasconcellos et al., 2020).

Therefore, grounded in SDT, the role of teachers in promoting positive socio-emotional classroom climates and shaping students’ interactions is highly significant. However, SDT conceptualizes relatedness as the subjective experience of feeling connected, accepted, and cared for by significant others, and it does not require interaction with the entire peer group for this need to be fulfilled (Deci and Ryan, 2014). That is, a student may satisfy their need for relatedness through a few meaningful relationships, without necessarily feeling integrated into the broader classroom community. This limitation makes it difficult for SDT alone to fully capture group-level dynamics such as class cohesion. Given that Spanish educational policies emphasize active methodologies and peer collaboration, fostering cooperation and positive peer relationships across the classroom is essential to optimize learning. In this context, the concept of class cohesion offers a complementary perspective that focuses on the collective experience of the classroom as a social unit, which has received significantly less attention in educational research (Leo et al., 2023d). Consequently, integrating the CMC allows us to address the theoretical and practical gap left by SDT in capturing the dynamics of peer-to-peer relationships on a class-wide scale.

Cohesion was defined by Carron et al. (1998) as “a dynamic process that is reflected in the tendency for a group to stick together and remain united in the pursuit of its instrumental objectives and/or for the satisfaction of member affective needs” (p. 213). In the educational context, class cohesion refers to students’ collaboration in achieving shared academic goals and common social bonds (Leo et al., 2022). This class cohesion can be observed in two main dimensions: task cohesion, which pertains to students’ collaboration in academic activities, and social cohesion, which relates to the strengthening of interpersonal and affective bonds among students (Leo et al., 2022).

In this regard, teachers also play a fundamental role in facilitating class cohesion within the classroom. They can implement strategies to enhance both task and social cohesion through structured activities inside and outside the classroom, fostering collaboration among students. These strategies may include assigning interdependent roles, responsibilities, and tasks, as well as promoting peer communication, peer assessment with formative purposes, and social skills development. Moreover, establishing shared goals, designing challenges that require mutual support, and creating opportunities for students to engage in meaningful interactions, where they can express their interests, concerns, and motivations, help cultivate an integrated and participatory learning environment (Leo et al., 2023d).

Previous research indicates that students who perceive themselves as part of a cohesive group tend to exhibit higher values in key variables related to learning processes, such as students’ autonomous motivation and engagement (Leo et al., 2023a, 2023d, 2023e). Therefore, designing training programs focused on providing PE teachers with relatedness-supportive and class cohesion strategies could foster a warm environment that promotes students’ social interactions and improves learning-related outcomes.

Previous SDT-based training programs among PE teachers have predominantly focused on how to provide autonomy support to students (Vasconcellos et al., 2020). Additionally, some SDT-based training programs among PE teachers have focused on both autonomy and competence support (Patzak and Zhang, 2025) or have simultaneously addressed all three basic psychological needs—autonomy, competence, and relatedness (Vasconcellos et al., 2020; White et al., 2021). Overall, the results from these studies indicate that teachers who participate in these training programs not only learn how to provide autonomy and competence support in their PE classes but also experience benefits, such as increased need satisfaction at work (Cheon et al., 2014, 2018; Tilga et al., 2021), relatedness satisfaction with their students (Reeve and Cheon, 2021), and greater job satisfaction (Cheon et al., 2014, 2020), among other positive outcomes. Additionally, students taught by trained teachers have demonstrated notable improvements in need satisfaction, need frustration, autonomous motivation and other (mal)adaptive outcomes in PE lessons (Vasconcellos et al., 2020; Reeve and Cheon, 2021). In contrast to these previous works, the present study focuses specifically on relatedness support, based on the premise that meaningful learning can be greatly facilitated through peer interaction within the classroom. Despite the recognized value of peer collaboration for learning and engagement, existing strategies to promote relatedness have typically been implemented alongside other strategies (i.e., autonomy support and competence support; Vasconcellos et al., 2020) and have rarely been applied in isolation (Sparks et al., 2017). As a result, the specific contribution of relatedness support strategies to students’ learning remains largely unexplored (Leo et al., 2023d). To address this gap, the present study integrates two complementary theoretical frameworks (i.e., SDT and CMC). This dual framework allows us to approach relatedness both as an individual psychological experience, in the context of teacher-student and student–student interactions (i.e., SDT), and class cohesion as a shared sense of connection among all classmates as a group (i.e., CMC), in line with the broader educational goal of fostering collaborative and socially rich learning environments.

Despite its theoretical relevance, to our knowledge, only one SDT-based training program in PE has exclusively focused on supporting students’ need for relatedness (Sparks et al., 2017). This cluster-randomized controlled study was conducted in four private Catholic secondary schools, where a three-hour teacher training program was delivered to 10 teachers in a single session. This was followed by two readings provided 1 month later to reinforce the learning. The program was structured into three sequential phases: (a) a theoretical introduction, providing background information on relatedness support; (b) a general presentation, outlining relatedness-supportive strategies using real-life examples and video images and their connection to student motivation; and (c) a last phase in which participants described how they supported relatedness in PE and identified strategies they could realistically implement. After the SDT-based training program, a four-month intervention program took place in PE classes (with two to three sessions per week), integrating relatedness-supportive strategies through different sports activities, basketball, netball, badminton, and Australian football. The results from the study (Sparks et al., 2017) indicated that intervention group teachers were significantly more knowledgeable about relatedness-supportive teaching than control group teachers. Moreover, intervention group students, compared to those in the control group, reported significant improvements in relatedness support from their PE teachers, enjoyment, other-efficacy (i.e., confidence in their teacher’s ability), and peer-focused related-inferred self-efficacy (i.e., perceived peer confidence in one’s abilities). However, no significant changes were observed in self-efficacy, teacher-focused related-inferred self-efficacy (i.e., perceived teacher confidence in one’s abilities), self-determination, and amotivation.

A limitation noted by the authors concerns the structure and duration of the training program. Sparks et al. (2017) suggested that a longer or multi-session intervention might be more suitable to enhance the impact and internalization of the training content by teachers. They also reflect on the need for more engaging and interactive follow-up activities beyond the materials initially provided. Furthermore, all data—except for teachers’ self-reported relatedness-supportive teaching—was gathered via student self-reports. Including additional teacher-report measures, or external observations of teachers’ relatedness-supportive behaviors, could help triangulate the results. Additionally, the study did not include a follow-up post-intervention measure, limiting the possibility to assess the long-term effects for both teachers and students. Finally, sex differences in the study variables were not examined for either students or teachers.

Despite these limitations, the findings reinforce the critical role of teachers in fostering interpersonal relationships among students in PE settings (Gairns et al., 2015). Furthermore, within the CMC, despite an extensive body of literature on intervention studies in sports contexts (Martin et al., 2009; Kwon, 2024), this model has not yet been applied to PE teachers to improve students’ interpersonal relationships (Leo et al., 2023d). Further long-term interventions aimed at effectively fostering students’ sense of relatedness, class cohesion, and learning outcomes in educational contexts are needed.

Despite the findings outlined above, there is still limited knowledge that has tested the malleability of teacher’ relatedness-supportive/thwarting behaviors and class cohesion and how these teaching practices contribute to students’ interactions and learning processes (Leo et al., 2023d; Vasconcellos et al., 2020; White et al., 2021). Building on this theoretical foundation and the growing interest in relatedness in PE, we developed the TRI-PE Project (Togetherness, Relatedness, and Interactions in Physical Education). This project aims to promote relatedness and class cohesion by providing teachers with strategies grounded in SDT and CMC. The acronym reflects the three core pillars of the study: togetherness, referring to students’ sense of unity and belonging; relatedness, understood as a basic psychological need; and interactions, highlighting the role of meaningful social exchanges in the classroom. Therefore, to extend previous knowledge, this mixed-method study describes the TRI-PE Project protocol of a teacher training program based on relatedness-supportive and class cohesion strategies, aimed at improving the instructional practices of PE teachers, as well as students’ interactions and learning-related outcomes (see Figure 1).

To address previous limitations, this study will extend the duration of the teacher training, ensuring that teachers acquire the necessary knowledge and skills to effectively implement relatedness and class cohesion strategies in their classes. To do so, the recommendations proposed by Reeve et al. (2022) for SDT-based training programs will be followed. Additionally, as recommended by Ahmadi et al. (2023), this training program will not only focus on relatedness-supportive behaviors but also on avoiding relatedness-thwarting behaviors, because both have been shown to significantly influence students’ motivational processes and adaptative outcomes (Vasconcellos et al., 2020). Importantly, teachers may learn relatedness supportive strategies while unintentionally maintaining relatedness thwarting behaviors, highlighting the need for awareness and reflection throughout the training. Furthermore, this SDT-based training program will incorporate class cohesion strategies to promote a sense of group belonging, ensuring that all students feel included, which can enhance peer learning and classroom integration.

According to the outcomes, several variables will be selected based on prior evidence identifying them as key motivation- and learning-related constructs (e.g., autonomous motivation, problematic relationships, group processing, learning, or academic performance; Vasconcellos et al., 2020). All study variables will also be examined by sex to determine whether the intervention is equally effective for boys and girls. Finally, a follow-up post-intervention measure will be implemented at the end of the academic year to evaluate the long-term effects of the intervention.

The TRI-PE project is a randomized controlled trial (RCT) to be conducted in secondary schools within the region of Extremadura. In this region, the academic calendar extends over three terms, from early September to mid-June, with holiday breaks in December–January for Christmas and in March or April for Easter. Specifically, PE is mandatory for all secondary students who attend two coeducational 50-min weekly classes. As illustrated in Figure 1, the intervention will last 10 months, with assessments conducted at three time points: (1) baseline measurement at the end of the first month of the school year (first term, end of September; T1) to ensure that students have had several weeks to a fine-grained picture of the variables under investigation; (2) post-implementation assessment (second term, April; T2); and (3) 2-month follow-up post-implementation at the end of the academic year (third term, June; T3). This study has been approved by the Ethics Committee of University of Extremadura [114/2023] and complies with the principles of the Declaration of Helsinki.

The intervention will consist of two phases for the experimental group: (1) a face-to-face teacher training phase, which includes two group sessions, one group booster session, and two individual follow-up sessions, and (2) an implementation phase, during which teachers will apply the strategies with their students (see Figure 1).

Various assessment instruments will be administered to all study participants at three different time points (September [T1], April [T2], and June [T3]; see Figure 1). During the administration of the students’ questionnaires, at least one research team member will be present in the classroom to address any questions or concerns, and teachers will be absent. Students will be informed that their responses are anonymous, and that neither teachers nor school staff will have access to individual data. The paper-based questionnaire will take approximately 15 min for both students and teachers to complete at each time point.

A mixed-method analysis will be conducted to evaluate the training program, as well as to assess the impact of its implementation in PE lessons on the study variables for both teachers and students. Regarding the quantitative analysis, first, a descriptive analysis will be conducted to evaluate both teachers’ and the external researcher’s perceptions of the training program, assessing aspects such as its innovation, practical relevance, and the feasibility of the strategies implemented. Second, to assess the impact of the intervention program on the study variables for both teachers and students, the nature of the variables will first be examined through tests of normality, validity, and reliability across the three measurements. Third, the assumptions of independence, linearity, and homogeneity of variance will be verified to ensure the appropriateness of analyses based on the general linear model. Fourth, between-group and within-group differences will be analyzed using repeated-measures multivariate analysis of covariance (MANCOVA). A 3 × 2 (Time × Condition) repeated measures MANCOVA will be performed for both teachers and students, with covariates such as age, sex, teaching experience, type of school, and school location for teachers, and age, sex, sociocultural background, and school grade for students. If parametric assumptions are not met, appropriate non-parametric alternatives such as the Wilcoxon signed-rank test (for within-group comparisons) and the Mann–Whitney U test (for between-group comparisons) will be used. Subsequently, to examine intragender differences of the intervention on study variables, a 3 × 2 × 2 (Time x Condition x Sex) repeated measures MANCOVA will be performed for both teachers and students. To further examine changes in each outcome variable over time (T1, T2, and T3) within each group (experimental vs. control), multiple paired t-tests with Bonferroni correction will be conducted. Effect sizes will be calculated using partial eta squared (η²ₚ). Effect size thresholds will be interpreted as small (η²ₚ > 0.01), moderate (η²ₚ > 0.06), or large (η²ₚ > 0.14) following Cohen’s criteria. For all analyses, the significance threshold will be set at p < 0.05. All statistical analyses will be conducted using IBM SPSS Statistics v.25.0. Finally, a longitudinal structural equation model will be employed through the statistical software Mplus (Muthén and Muthén, 1998-2019) to analyze the predictive relationships between the study variables, allowing for the observation of potential differences at the three specific times (T1, T2, and T3) when data are collected.

Regarding the qualitative analysis, the qualitative data from the focus group will be transcribed and managed using NVivo Version 11.0 to ensure systematic organization. A thematic analysis following the procedures outlined by Braun and Clarke (2019) will be employed. Initially, three researchers will independently examine the transcripts to familiarize themselves with the content. Relevant excerpts reflecting teachers’ views on the training program’s outcomes and its application with students will then be identified. After coding, final themes and subthemes will be refined to accurately capture the core meanings. The analysis will adopt a deductive approach, grounded in SDT and the CMC, given most of the questions align with these theoretical frameworks. Additionally, two researchers will oversee the process, contributing their insights to support consensus in the interpretation of results.

This intervention faces certain limitations that should be considered. Firstly, although the first part of the training program can be considered brief to ensure that PE teachers effectively integrate these techniques into their PE classes, an excessively long duration could discourage their participation. Nevertheless, a booster session will be scheduled 3 months after the first two sessions of the training program. Secondly, to avoid overburdening students, we will assess their perceptions of teachers’ autonomy- and competence-supportive/thwarting behaviors with a single item to control for its effects in the analysis, which may limit our ability to fully gauge their impact. In contrast, teachers will complete the full set of items for both need-supportive and need-thwarting behaviors to control for these effects in the analysis. Thirdly, while students’ perceptions of class cohesion will be measured using a validated scale (Leo et al., 2023c), we were unable to assess class cohesion support, understood as the specific teacher behaviors aimed at promoting task cohesion (e.g., “The teacher encourages us to help each other during the development of tasks and activities) and social cohesion (e.g., “The teacher encourages us to participate together in activities outside of class.”). Fourthly, to assess the fidelity of the intervention, only two classes will be randomly observed for each experimental group teacher due to a lack of human resources. Finally, although all teachers will receive the same training program, each teacher will need to adapt the strategies to their context, the characteristics of their students, available spaces, material resources, etc. Therefore, the number and intensity of the use of relatedness supportive and class cohesion strategies may vary slightly depending on each group.