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Recommendations for determining the validity of consumer wearable and smartphone step count: expert statement and checklist of the INTERLIVE network
  1. William Johnston1,2,
  2. Pedro B Judice3,4,
  3. Pablo Molina García5,
  4. Jan M Mühlen6,
  5. Esben Lykke Skovgaard7,
  6. Julie Stang8,
  7. Moritz Schumann6,9,
  8. Shulin Cheng6,9,
  9. Wilhelm Bloch6,
  10. Jan Christian Brønd7,
  11. Ulf Ekelund8,
  12. Anders Grøntved7,
  13. Brian Caulfield1,2,
  14. Francisco B Ortega5,
  15. Luis B Sardinha4
  1. 1Insight Centre for Data Analytics, University College Dublin, Dublin, Ireland
  2. 2School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
  3. 3Centro de Investigação em Desporto, Educação Física e Exercício e Saúde, CIDEFES, Universidade Lusófona, Lisbon, Portugal
  4. 4Exercise and Health Laboratory, CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz-Quebrada, Portugal
  5. 5PROFITH (PROmoting FITness and Health through physical activity) Research Group, Department of Physical Education and Sports, Faculty of Sport Sciences, Sport and Health University Research Institute (iMUDS), University of Granada, Granada, Spain
  6. 6Institute of Cardiovascular Research and Sports Medicine, Department of Molecular and Cellular Sports Medicine, German Sport University, Cologne, Germany
  7. 7Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense M, Denmark
  8. 8Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway
  9. 9Exercise Translational Medicine Centre, the Key Laboratory of Systems Biomedicine, Ministry of Education, and Exercise, Health and Technology Centre, Department of Physical Education, Shanghai Jiao Tong University, Shanghai, China
  1. Correspondence to Professor Luis B Sardinha, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz-Quebrada 1499-002 Lisboa, Portugal; lsardinha{at}


Consumer wearable and smartphone devices provide an accessible means to objectively measure physical activity (PA) through step counts. With the increasing proliferation of this technology, consumers, practitioners and researchers are interested in leveraging these devices as a means to track and facilitate PA behavioural change. However, while the acceptance of these devices is increasing, the validity of many consumer devices have not been rigorously and transparently evaluated. The Towards Intelligent Health and Well-Being Network of Physical Activity Assessment (INTERLIVE) is a joint European initiative of six universities and one industrial partner. The consortium was founded in 2019 and strives to develop best-practice recommendations for evaluating the validity of consumer wearables and smartphones. This expert statement presents a best-practice consumer wearable and smartphone step counter validation protocol. A two-step process was used to aggregate data and form a scientific foundation for the development of an optimal and feasible validation protocol: (1) a systematic literature review and (2) additional searches of the wider literature pertaining to factors that may introduce bias during the validation of these devices. The systematic literature review process identified 2897 potential articles, with 85 articles deemed eligible for the final dataset. From the synthesised data, we identified a set of six key domains to be considered during design and reporting of validation studies: target population, criterion measure, index measure, validation conditions, data processing and statistical analysis. Based on these six domains, a set of key variables of interest were identified and a ‘basic’ and ‘advanced’ multistage protocol for the validation of consumer wearable and smartphone step counters was developed. The INTERLIVE consortium recommends that the proposed protocol is used when considering the validation of any consumer wearable or smartphone step counter. Checklists have been provided to guide validation protocol development and reporting. The network also provide guidance for future research activities, highlighting the imminent need for the development of feasible alternative ‘gold-standard’ criterion measures for free-living validation. Adherence to these validation and reporting standards will help ensure methodological and reporting consistency, facilitating comparison between consumer devices. Ultimately, this will ensure that as these devices are integrated into standard medical care, consumers, practitioners, industry and researchers can use this technology safely and to its full potential.

  • accelerometer
  • physical activity
  • walking
  • validity
  • consensus statement

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  • Twitter @Will_Johns10, @moritz_schumann, @Ulf_Ekelund

  • WJ, PBJ and PMG contributed equally.

  • Contributors All authors were involved in the development and drafting of the expert statement. All authors have read and approved the content of the manuscript.

  • Funding PBJ is supported by the Portuguese Foundation for Science and Technology (SFRH/BPD/115977/2016). WJ is partly funded by Science Foundation Ireland (12/RC/2289_P2). PMG and FBO are supported by grants from the MINECO/FEDER (DEP2016‐79512‐R) and from the University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence; Scientific Excellence Unit on Exercise and Health (UCEES); Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Funds (ref. SOMM17/6107/UGR). JMM is partly funded by Private Stiftung Ewald Marquardt für Wissenschaft und Technik, Kunst und Kultur. UE and JS are partly funded by the Research Council of Norway (249932/F20). AG is supported a European Research Council Grant (grant number 716657). ELS is supported by TrygFonden (grant number 310081). This research was partly funded by Huawei Technologies, Finland.

  • Competing interests None declared.

  • Patient consent for publication Not required.

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