**Improving motivational interaction styles of physical activity promotion and sports professionals: Towards a complex dynamical systems approach (MotiStyleSport)** Motivational interaction style among physical education teachers, as well as professionals involved in physical activity (PA) counseling and coaching influences outcomes in their target groups, e.g. increase PA and decrease dropout intentions from sports. An empowering and dialogical interaction style has been shown to result in more beneficial outcomes than a controlling interaction style. Although it is possible to change one’s style, current research literature falls short of explaining how this can be done efficiently and sustainably. This project investigates how to enhance professionals’ training to improve their interaction styles. We will examine comprehensively what pathways professionals take to change their interaction style, and how feasible and acceptable interaction style trainings are face-to-face and online. Team: Melina Puolamäki, Elina Renko, Matti Heino, Nelli Hankonen Funding: Sport Sciences Projects, Ministry of Education and Culture, Finland *** Projektista suomeksi: [Liikunnan ja urheilun ammattilaisten motivoivan vuorovaikutuksen taitojen parantamista koskeva tutkimus käynnistyy][1] [1]: https://www2.helsinki.fi/fi/researchgroups/behaviour-change-and-wellbeing/liikunnan-ja-urheilun-ammattilaisten-motivoivan-vuorovaikutuksen-taitojen-parantamista-koskeva-tutkimus-kaynnistyy