Effects of school-based interventions on motivation towards physical activity in children and adolescents protocol for a systematic review - Demetriou, Yolanda; Reimers, Anne K.; Alesi, Marianna; Scifo, Lidia; Chicau Borrego, Carla; Monteiro, Diogo; Kelso, Anne (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2019)