Related Experiment Video
Updated: May 28, 2026
Assessing the Accuracy of Fitness Smartwatch Data for Cardiovascular and Physical Activity Monitoring: A Validation Study in Digital Health
Published on: February 21, 2025
Validity and reliability of smartwatch-based upper-extremity function and heart rate assessment in outpatient older
Mohammad Hosseinalizadeh1, Mehran Asghari2, Hossein Ehsani2
1Department of Biomedical Engineering, School of Graduate Studies, Rutgers University, NJ, United States; Department of Rehabilitation and Movement Sciences, School of Health Professions, Rutgers University, NJ, United States.
Background:
We previously developed and validated a 20-second upper extremity function (UEF) test for frailty assessment using wearable-derived motor and heart rate (HR) metrics.
Objectives:
To evaluate, among older adults in hospital, the validity of a smartwatch for extracting UEF motor and HR outcomes relative to wearable sensors, and the test-retest reliability of UEF motor and HR outcomes across two back-to-back trials.
Methods:
Adults ≥65 years performed the UEF task. Motor outcomes included elbow angular speed, moment, range of motion, speed reduction, and speed variability. HR outcomes included mean HR during baseline, task, and post-task, and measures of HR increase and recovery. In Experiment I (validation), motor outcomes were compared between motion sensor and smartwatch (n = 43; age=68.98 ± 13.3), and HR outcomes between ECG sensor and smartwatch (n = 23; age=77.26 ± 8.62). In Experiment II, test-retest reliability was quantified for motor outcomes (n = 133; age=73.04 ± 10.99) and HR outcomes (n = 85; age=74.53 ± 9.83). Agreement and repeatability were quantified using two-way mixed effects intraclass correlation coefficients (ICC).
Results:
Smartwatch demonstrated moderate-to-excellent agreement with the motion sensor (ICC = 0.67-0.90) and good-to-excellent agreement for most (78%) HR features (ICC = 0.75-0.94). Test-retest reliability within repeated trials was good-to-excellent for most (83%) motor outcomes (ICC = 0.75-0.96), and for most (78%) HR outcomes (ICC = 0.80-0.96).
Conclusions:
A brief seated UEF assessment provides reproducible motor and HR-derived measures in clinic. Further a smartwatch may capture UEF motor outcomes and most HR features with agreement relative to reference sensors.
