Comparison of Trial Participants and Open Access Users of a Web-Based Physical Activity Intervention Regarding Adherence, Attrition, and Repeated Participation

Miriam Wanner   ^{1, 2 †} , PhD ;   Eva Martin-Diener   ^{1 †} , MPH ;   Georg Bauer   ^{3, 4 †} , MD DrPH ;   Charlotte Braun-Fahrländer   ^{2 †} , MD ;   Brian W Martin   ^{3 †} , MD MPH

¹ Swiss Federal Institute of Sport Magglingen, Magglingen, Switzerland

² Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland

³ Institute of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland

⁴ Division of Public and Organizational Health, University and ETH Zurich, Zurich, Switzerland