%0 Journal Article
%@ 2561-7605
%I JMIR Publications
%V 8
%N 
%P e67322
%T A Smartphone-Based Timed Up and Go Test Self-Assessment for Older Adults: Validity and Reliability Study
%A Böttinger,Melissa Johanna
%A Mellone,Sabato
%A Klenk,Jochen
%A Jansen,Carl-Philipp
%A Stefanakis,Marios
%A Litz,Elena
%A Bredenbrock,Anastasia
%A Fischer,Jan-Philipp
%A Bauer,Jürgen M
%A Becker,Clemens
%A Gordt-Oesterwind,Katharina
%K timed up and go test
%K self-assessment
%K instrumented assessment
%K technology-based assess-ment
%K physical capacity
%K mobility
%K aged
%K mobile applications
%K smartphone
%K diagnostic self evaluation
%D 2025
%7 21.3.2025
%9 
%J JMIR Aging
%G English
%X Background: The Timed Up and Go test (TUG) is recommended as an evidence-based tool for measuring physical capacity. Instrumented TUG (iTUG) approaches expand classical supervised clinical applications offering the potential of self-assessment for older adults. Objective: This study aimed to evaluate the concurrent validity and test-retest reliability of a smartphone-based TUG self-assessment “up&go app.” Methods: A total of 52 community-dwelling older adults (>67 years old) were recruited. A validated and medically certified system attached with a belt at the lower back was used as a reference system to validate the “up&go app” algorithm. The participants repeated the TUG 5 times wearing, a smartphone with the “up&go app” in their front trouser pocket and an inertial sensor to test the concurrent validity. A subsample of 37 participants repeated the “up&go app” measurement 2 weeks later to examine the test-retest reliability. Results: The correlation between the “up&go app” and the reference measurement was r=0.99 for the total test duration and r=0.97 for the 5 single repetitions. Agreement between the 5 repetitions was intraclass correlation coefficient (ICC)=0.9 (0.84‐0.94). Leaving out the first repetition, the agreement was ICC=0.95 (0.92‐0.97). Test-retest agreement had an ICC=0.79 (0.53‐0.9). Conclusions: The duration of 5 repetitions of the TUG test, measured with the pocket-worn “up&go app,” was very consistent with the results of a lower-back sensor system, indicating excellent concurrent validity. Participants walked slower in the first round than in the other 4 repetitions within a test run. Test-retest reliability was also excellent. The “up&go app” provides a useful smartphone-based approach to measure 5 repetitions of the TUG. The app could be used by older adults as a self-screening and monitoring tool of physical capacity at home and thereby help to early identify functional limitations and take interventions when necessary. 
%R 10.2196/67322
%U https://aging.jmir.org/2025/1/e67322
%U https://doi.org/10.2196/67322