Validity of the Apple Watch® for monitoring push counts in people using manual wheelchairs

Kati S Karinharju; Alexandra M Boughey; Sean M Tweedy; Kelly M Clanchy; Stewart G Trost; Sjaan R Gomersall

doi:10.1080/10790268.2019.1576444

Validity of the Apple Watch^® for monitoring push counts in people using manual wheelchairs

J Spinal Cord Med. 2021 Mar;44(2):212-220. doi: 10.1080/10790268.2019.1576444. Epub 2019 Feb 27.

Authors

Kati S Karinharju^{1

2}, Alexandra M Boughey³, Sean M Tweedy^{1

4}, Kelly M Clanchy⁵, Stewart G Trost⁶, Sjaan R Gomersall³

Affiliations

¹ School of Human Movement and Nutrition Sciences, The University of Queensland, St Lucia, QLD, Australia.
² Satakunta University of Applied Sciences, Pori, Finland.
³ School of Health and Rehabilitation Sciences, The University of Queensland, St Lucia, QLD, Australia.
⁴ I.M. Sechenov First Moscow State Medical University, Moscow, Russia.
⁵ School of Allied Health Sciences, Griffith University, Southport, QLD, Australia.
⁶ Institute of Health and Biomedical Innovation at Queensland Centre for Children's Health, Research, Queensland University of Technology, South Brisbane, QLD, Australia.

Abstract

Objective: A recent Apple Watch^® activity-monitoring innovation permits manual wheelchair users to monitor daily push counts. This study evaluated the validity of the Apple Watch^® push count estimate.Design: Criterion validity.Setting: Southern Finland and Southeast Queensland, Australia.Participants: Twenty-six manual wheelchair users from Finland and Australia were filmed completing a standardized battery of activities while wearing the Apple Watch^® (dominant wrist).Outcome Measures: Wheelchair pushes as determined by the Apple Watch^® were compared to directly observed pushes.Results: Agreement between Apple Watch^® push counts and directly observed pushes was evaluated using Intraclass correlation coefficients (ICC), Pearson correlations and Bland-Altman analyses. Apple Watch^® pushes and directly observed push counts were strongly correlated (ICC = 0.77, P < 0.01) (r = 0.84, P < 0.01). Bland Altman plots indicated that the Apple Watch^® underestimated push counts (M = -103; 95% ULoA = 217; LLoA = -423 pushes). Mean absolute percentage error was 13.5% which is comparable to studies evaluating agreement between pedometer-based step counts and directly observed steps.Conclusion: Apple Watch^® push-count estimates are acceptable for personal, self-monitoring purposes and for research entailing group-level analyses, but less acceptable where accurate push-count measures for an individual is required.

Keywords: Apple Watch®; Monitoring; Physical activity; Push counts; Wheelchair.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Australia
Disabled Persons*
Humans
Monitoring, Physiologic
Reproducibility of Results
Spinal Cord Injuries*
Wheelchairs*