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Letters to the Editor (29) Non-Randomized Study Protocols and Methods (Non-eHealth) (1296) Telehealth and Telemonitoring (3177) Methods and Feasibility Studies (780) Wearable Devices and Sensors (1672) Autism Spectrum Disorder (ASD) (223) Validity, Reliability, and Bias (150)

Published on in Vol 15 (2026)

Preprints (earlier versions) of this paper are available at https://preprints.jmir.org/preprint/110988, first published .
Man's hand interacting with a black fitness tracker smart band on his wrist.

Accelerometer-Based Step Counts May Be Confounded by Repetitive Motor Behaviors in Adults With Autism Spectrum Disorder

Accelerometer-Based Step Counts May Be Confounded by Repetitive Motor Behaviors in Adults With Autism Spectrum Disorder

Authors of this article:

Muhammad Anas Malik1 Author Orcid Image ;   Tayeba Fatima2 Author Orcid Image
Article Authors Cited by Tweetations Metrics

    1Ameer-ud-din Medical College, 6-Abdur Rehman Chughtai Road (Birdwood Road), near Jail Road, Shadman, Lahore, Punjab, Pakistan

    2Avicenna Medical College, Lahore, Punjab, Pakistan

    *all authors contributed equally

    Corresponding Author:

    Muhammad Anas Malik


    JMIR Res Protoc 2026;15:e110988

    doi:10.2196/110988

    Keywords

    autism spectrum disorder; physical activity; co-participation; family support; autism in adulthood; telehealth; wearable devices; physical function; remote assessment; health disparities; minority health; adult autism; protocol study; cross-sectional design; patient-reported outcomes; motor impairments; rehabilitation; digital health 

    We read with interest the recent pilot study by Nunez-Gaunaurd et al [1] involving remote assessment of physical activity and physical function in adults with autism spectrum disorder (ASD). The integration of accelerometer-based step monitoring with remote performance-based and patient-reported measures represents a valuable step toward accessible, telehealth-based functional assessment in an underserved population. However, we found one measurement concern relevant to the study’s validity aims.

    Consumer accelerometers such as the Fitbit Inspire 3 estimate step counts using gait-pattern algorithms calibrated primarily on people with neurotypical ambulatory movements, and even in this population, they can record false step counts, as mentioned in a recent study [2]. Adults with ASD frequently exhibit repetitive, uncontrolled motor behaviors like hand flapping, rocking, and pacing that generate rhythmic upper- and lower-limb acceleration signals that are distinct from ambulatory movements during walking and can potentially be misclassified as ambulatory steps [3]. The study by Nunez-Gaunaurd et al [1] proposes using step counts per day as a criterion indicator to establish the construct validity of Patient-Reported Outcomes Measurement Information System (PROMIS) physical function scores, so any systematic over- or undercounting of steps due to characteristic ASD movement patterns could bias this validation. This concern is distinct from the generalizability and sampling limitations the authors already mentioned in this population.

    We would ask the study team whether they have planned or piloted any validation of Fitbit-derived step counts against a gold standard method, like video-coded step counts, in a subsample of participants with prominent motor stereotypes, which would help establish whether this measure can be trusted as a criterion standard in this population [4].

    This is an addressable question rather than a fundamental design flaw, and clarification would strengthen confidence in the study’s future findings.

    Funding

    This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

    Authors' Contributions

    Both authors contributed equally and are accountable for the content of this letter.

    Conflicts of Interest

    None declared.

    1. Nunez-Gaunaurd A, Tovin MM, Hale M, Li T, Bhat A. Remote assessment of physical function and physical activity in adults with autism spectrum disorder: protocol for feasibility, validity, and reliability study. JMIR Res Protoc. Aug 31, 2026;15:e86020. [CrossRef] [Medline]
    2. Modave F, Guo Y, Bian J, et al. Mobile device accuracy for step counting across age groups. JMIR Mhealth Uhealth. Jun 28, 2017;5(6):e88. [CrossRef] [Medline]
    3. Melo C, Ruano L, Jorge J, et al. Prevalence and determinants of motor stereotypies in autism spectrum disorder: a systematic review and meta-analysis. Autism. Apr 2020;24(3):569-590. [CrossRef] [Medline]
    4. Toth LP, Park S, Springer CM, Feyerabend MD, Steeves JA, Bassett DR. Video-recorded validation of wearable step counters under free-living conditions. Med Sci Sports Exerc. Jun 2018;50(6):1315-1322. [CrossRef] [Medline]

    ‎
    ASD: autism spectrum disorder
    PROMIS: Patient-Reported Outcomes Measurement Information System

    Edited by Surya Nedunchezhiyan; This is a non–peer-reviewed article. submitted 01.Sep.2026; accepted 09.Oct.2026; published 30.Oct.2026.

    Copyright

    © Muhammad Anas Malik, Tayeba Fatima. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 30.Oct.2026.

    This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR Research Protocols, is properly cited. The complete bibliographic information, a link to the original publication on https://www.researchprotocols.org, as well as this copyright and license information must be included.