2.1. Search Strategy

Systematic searches were conducted across the following eight databases: AMED, CINAHL, Embase, IEEE, Medline, PsycINFO, Web of Science and Scopus. In addition to the above databases, reference lists of review articles and included studies were hand searched to identify additional relevant studies. The search criteria were limited to studies conducted in the English language. An initial search included articles published between 1 January 2010 and 18 January 2021. A follow-up search was conducted on 25 November 2022. A lower limit of 2010 was chosen given the rapid technological advancement in the design and development of accelerometers which are not comparable to those currently used.

The search terms were grouped into four categories and searched in the following sequence: (a) accelerometry/wearable devices (MESH term used—“Fitness Trackers”, “Accelerometry or Actigraphy”, “Wearable Electronic Devices”) (b) physical activity (MESH term used—“exercise”, “running”, “swimming”, “walking”, “motor activity”, “freezing reaction”, “cataleptic”) (c) older adults (MESH term used—“aged”, “aged, 65 and over”) (d) clinimetric properties (MESH term used—“reproducibility of results”, “sensitivity and specificity”). Further details of the search strategy are provided in Supplementary Table S1.