Biofeedback and Digitalized Motivational Interviewing to Increase Daily Physical Activity: Series of Factorial N-of-1 Randomized Controlled Trials Piloting the Precious App

Johanna Nurmi   ^{1, 2} , PhD ;   Keegan Knittle   ^{1, 3} , PhD ;   Felix Naughton   ⁴ , PhD ;   Stephen Sutton   ² , PhD ;   Todor Ginchev   ⁵ , MSc ;   Fida Khattak   ⁵ , MSc ;   Carmina Castellano-Tejedor   ^{6, 7, 8} , PhD ;   Pilar Lusilla-Palacios   ^{8, 9, 10, 11} , MD, PhD ;   Niklas Ravaja   ¹² , PhD ;   Ari Haukkala   ^{1, 13 †} , PhD

¹ Social Psychology, Faculty of Social Sciences, University of Helsinki, Helsinki, Finland

² Behavioural Science Group, Primary Care Unit, Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom

³ Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland

⁴ Behavioural and Implementation Science Group, School of Health Sciences, University of East Anglia, Norwich, United Kingdom

⁵ Department of Communications and Networking, Aalto University, Espoo, Finland

⁶ Grupo de Investigación en Estrés y Salud, Basic Psychology Department, Autonomous University of Barcelona, Barcelona, Spain

⁷ Research Group on Aging, Frailty and Care Transitions in Barcelona, Parc Sanitari Pere Virgili & Vall d’Hebron Research Institute, Barcelona, Spain

⁸ Psiquiatría, Salud Mental y Adicciones, Vall d’Hebron Institut de Recerca, Barcelona, Spain

⁹ Servicio de Psiquiatría, Hospital Universitari Vall d’Hebron, Barcelona, Spain

¹⁰ Departament de Psiquiatria i Medicina Legal, Universitat Autònoma de Barcelona, Barcelona, Spain

¹¹ Centro de Investigación Biomédica en Red de Salud Mental, Instituto de Salud Carlos III, Barcelona, Spain

¹² Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland

¹³ Helsinki Collegium for Advanced Studies, University of Helsinki, Helsinki, Finland

†deceased