Using behaviour change science in changing motivational interaction behaviours: Stepwise development and acceptability study of the MotiStyleSport intervention

Background: Physical activity (PA) counselling and sports coaching are more effective when professionals use motivational interaction as outlined by the self-determination theory (SDT). Interaction training interventions generally consist of information provision and practical exercises such as role play, and show modest, short-term effects. Insights of behaviour change science have rarely been incorporated, despite their potential to support sustainable change. Aims: This study is the first to systematically apply insights from behaviour change science to develop an intervention to train professionals in motivational interaction behaviours. Methods: A four-step mixed-methods design included questionnaires (n=203 and n=15), and group interviews (n=15). Systematic intervention development involved, 1) identification of motivational interaction behaviours, determinants and behaviour change strategies, 2) formulation of an intervention theory of change, 3) co-development of intervention materials, and 4) acceptability evaluation using questionnaires and group interviews (n=15), for which qualitative data were content analysed and means and medians of quantitative data were explored. Results: 1) We selected nine motivational interaction behaviours such as asking open questions and clarifying expectations. Key behavioural determinants were identified (e.g., self-efficacy) and evidence-informed effective intervention strategies were selected. 2) Insights from behavioural science led to the addition of self-monitoring activities, action and coping planning tasks, and habit formation exercises. The intervention was delivered via 3) an online platform, slide shows, videos and homework. 4) Evaluation showed two activities needed optimisation: self-insight maps to explore personal antecedents for (de)motivational interaction and implementation intentions to foster habit formation. Issues concerned the acceptability dimensions of intervention coherence, perceived effectiveness, and self-efficacy. Conclusion: This study showcases how behaviour change principles can be used in designing highly acceptable interventions to change interaction behaviours. Particularly habit theory-based exercises show promise for future use.