Designing and Conducting an Activity Monitor Validation Study: A Scoping Review of Current Frameworks and Recommendations

Several decisions are required when testing whether an activity monitor accurately measures what it is supposed to. Multiple frameworks have proposed recommendations for validation studies, but the extent to which they provide (in)consistent methodological guidance is unclear. We compared existing frameworks and guidelines for conducting wearable activity monitor validation studies, with emphasis on study design and other conduct-related methodological elements. A preregistered scoping review was conducted following Preferred Reporting Items for Systematic Review and Meta-Analysis Statement extension for Scoping Reviews guidelines and registered in Open Science Framework. Searches of Scopus, MEDLINE, EMBASE, CINAHL, and Academic Search Premier were completed through August 2025 (initial: n = 6,295 articles). Data were extracted descriptively and synthesized narratively. Eleven documents were included ( n = 4 standards documents, n = 4 consensus statements, n = 2 systematic reviews with guidelines, and n = 1 methodological framework). Some recommended combining laboratory and free-living evaluation ( n = 5/11), although two described staged validation approaches. Minimum sample size recommendations were provided in 7/11 and ranged from ∼20 to 45 participants. Some frameworks ( n = 8/11) emphasized heterogeneous participant samples, although the individual-specific factors encouraged to consider was variable (age, mobility level, etc.). Guidance regarding monitor type and wearing location was limited, typically deferring to manufacturer instructions ( n = 7/11), except one recommending outcome-specific placement. Recommendations also differed in activity protocols (e.g., multistaged vs. context-based), criterion measures (e.g., video observation vs. manual step counting), and reporting considerations (e.g., age, sex, ethnicity, and body size). Existing validation frameworks show areas of agreement but substantial methodological variability. More harmonized conduct-related guidance may improve comparability across validation studies and strengthen interpretation of wearable-derived behavioral outcomes.