Existing research demonstrates a strong link between teachers' interaction styles and students' motivation, well-being, and physical activity (PA) engagement. However, despite the positive impacts of motivational interaction training, many trainees struggle to implement these skills effectively. This study focuses on pre-service PE teachers, a group crucial for promoting PA in students. The Let's Move It (LMI) trial intervention, underpinned by self-determination theory (SDT) and motivational interviewing (MI), provides a framework for this research. SDT emphasizes the importance of autonomy, competence, and relatedness in fostering motivation. MI, initially developed for clinical settings, promotes collaboration, acceptance, and evocation. The LMI intervention synthesized these approaches into ten interaction principles and seven practical techniques, carefully selected for feasibility, effectiveness, and theoretical coherence (Table 1 shows the mapping of these techniques to MI and SDT taxonomies). Previous research suggests that practical application opportunities and feedback are critical for successful skill adoption in MI and SDT training. While SDT-based studies have shown teachers' capacity to adapt autonomy-supportive behaviors, MI-based research points to the need for improved skill adoption. This study examines the experiences of pre-service teachers, a group potentially more receptive to adopting new habits before entrenched teaching practices develop. By exploring the benefits and concerns experienced when implementing motivational techniques, this research aims to improve the acceptability and effectiveness of future training programs. This study uses Sekhon's Theoretical Framework of Acceptability, which posits acceptability as a crucial factor in determining the intention to engage with an intervention, and thus a necessary condition for successful implementation.

The literature extensively supports the influence of teachers' interaction styles on student motivation and well-being, impacting academic performance and physical activity levels. Meta-analyses of motivational interaction training courses have consistently shown that while such training improves interaction styles, most trainees fail to fully utilize these newly acquired skills in practice. This gap between training and effective implementation raises important questions about how to improve the design and delivery of such training programs. Studies using SDT have shown teachers adopting behaviors that support autonomy, competence, and relatedness, although research on MI-based training highlights the need for improved skill adoption. The existing research on the integration of SDT and MI in educational practice largely focuses on in-service teachers, overlooking the potential benefits of incorporating this approach in pre-service training. The current research aims to address this gap by studying pre-service PE teachers and gaining insight into the practical challenges and benefits of this intervention.

Pre-service PE teachers (n=114) were offered an optional, advanced-level course on motivational interaction at the University of Jyväskylä. 35 students enrolled (30%). A total of 33 completed the course. Two cohorts completed the same 16-hour course, which involved interactive exercises, discussions, and practical application of seven techniques based on SDT and MI principles (Table 1). Participants kept diaries documenting their experiences using the techniques. All 19 students who consented participated in semi-structured interviews (14 female, 5 male), lasting 26-68 minutes. Interviews were conducted by two researchers without prior involvement in the course delivery or experience in PA promotion to ensure impartiality. Interviews were conducted either in person or online based on participant preference. The interview guide was focused on (1) the training content, (2) the techniques' feasibility and effectiveness, and (3) additional support mechanisms used. Interviews were audio-recorded, transcribed verbatim, and analyzed using a mixed-methods approach. First, narrative analysis identified two dominant storylines: enthusiastic/optimistic and partly reluctant. Then, inductive content analysis was conducted focusing on the benefits and concerns associated with each technique. Open coding, category creation, and abstraction were employed to categorize these benefits and concerns. The research team regularly discussed the coding and analysis to ensure trustworthiness. This rigorous analysis involved examining both manifest and latent content and considering researcher positionality.

Participants reported positive professional transformations through motivational interaction training. The benefits of each technique aligned with its intended function (Table 2). For example, positive feedback and appreciation were associated with reduced conflict, better relationships, and increased student motivation. However, concerns emerged across four categories: **1. Group Setting Challenges:** Most techniques proved difficult in group settings due to time constraints (especially empathetic listening) and the need for rapid responses in conflict situations (understanding resistance). Providing structure and rationale was also viewed as possibly conflicting with the desired less-structured nature of PE lessons. Giving positive feedback and appreciation equally to all students was seen as particularly challenging. **2. Role Demands Mismatch:** Techniques like understanding resistance, advising without pressing, providing choice, and giving positive feedback were seen as conflicting with the traditional teacher's role of giving instructions and maintaining control. Providing choice was also seen as potentially relinquishing control, which raised concerns about maintaining order. There were concerns that promoting choices might lead students to select easier tasks and that constant positive feedback would hinder the students' ability to accept criticism. **3. Undesired Interaction Effects:** Participants feared that techniques might feel forced, awkward, or patronizing. Empathetic listening and open questions raised concerns about potential reluctance from students to self-disclose. Paraphrasing felt awkward to some. Choosing the right words for non-controlling language and open questions was also deemed challenging. Giving positive feedback was sometimes seen as leading to awkward situations. **4. Target Behavior-Related Concerns:** Concerns about providing choice revolved around finding the right balance of choices; too many choices felt overwhelming, too few created indecision. Providing positive feedback was viewed as difficult when students behaved poorly; the challenge was in finding something positive to focus on even in negative situations. The ability to give appropriate and targeted feedback was highlighted as key for effective motivational interaction. Table 3 summarizes the concerns by technique and provides specific suggestions.

This study revealed a complex interplay between the benefits and concerns of using motivational interaction in PE teaching. Concerns often stemmed from a perceived conflict between the new interaction style and the traditional teacher's role. These concerns are consistent with previous research suggesting that teachers often believe excessive autonomy support leads to chaos. The findings link to the antecedents of need-supportive and controlling styles, with concerns about group situations linked to external pressures like time management and cultural norms around the teacher's role. Concerns also reflected the perceived impact on students' behaviors and motivations. This highlights the challenge of transitioning from a traditional expert model to a more student-centered, motivational approach. This aligns with the "expert trap" in MI, where professionals inadvertently assume an authoritative role, hindering client engagement. The benefits and concerns relate to Sekhon's Theoretical Framework of Acceptability. Concerns encompassed affective attitudes, burden, ethicality, intervention coherence, opportunity costs, perceived effectiveness, and self-efficacy, emphasizing the need to incorporate acceptability considerations into training programs. The benefits largely pertained to affective attitudes and perceived effectiveness.

This study provides valuable insights into the challenges and rewards of integrating motivational interaction into PE teaching. The findings highlight the need for training programs that address pre-service teachers' concerns regarding time management, role expectations, and potential interaction complexities. Future training should incorporate strategies to help teachers navigate the balance between autonomy support and structure, ensuring the appropriate application of techniques in diverse classroom settings. Further research should explore the long-term impact of this approach on both teacher efficacy and student outcomes. Development of tailored interventions incorporating self-regulation strategies and habit formation techniques is crucial to help teachers effectively transition to this new pedagogical approach in their unique contexts.

This study's findings are based on a sample of pre-service PE teachers in Finland and might not be generalizable to other populations. The time frame between training and interviews varied, potentially impacting the accuracy of reported experiences. While the research aimed to limit bias, the interviewers' lack of experience in PE and PA promotion could have influenced the information elicited during the interviews. The study primarily focused on the teachers' experiences of using specific techniques and might not fully capture the broader implications of adopting the motivational interaction style. Future research could examine the effects of this interaction style on student behavior and long-term outcomes, comparing objectively measured PA in addition to self-reported data.