Counting Steps in Activities of Daily Living in People With a Chronic Disease Using Nine Commercially Available Fitness Trackers: Cross-Sectional Validity Study

Darcy Ummels   ^{1, 2, 3} , MSc ;   Emmylou Beekman   ^{1, 2, 3} , PhD ;   Kyra Theunissen   ¹ , MSc ;   Susy Braun   ^{4, 5} , PhD ;   Anna J Beurskens   ^{1, 3} , PhD

¹ Research Centre for Autonomy and Participation of Persons with a Chronic Illness, Zuyd University of Applied Sciences, Heerlen, The Netherlands

² ParaMedisch Centrum Zuid, Sittard, The Netherlands

³ Care and Public Health Research Institute School for Public Health and Primary Care, Department of Family Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands

⁴ Research Centre for Nutrition, Lifestyle and Exercise, Zuyd University of Applied Sciences, Heerlen, The Netherlands

⁵ Care and Public Health Research Institute School for Public Health and Primary Care, Department of Health Services Research, Maastricht University Medical Centre, Maastricht, The Netherlands