College of Graduate Studies: Theses & Dissertations

Term of Award

Spring 2026

Degree Name

Master of Science in Kinesiology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Health and Kinesiology

Committee Chair

Andrew Flatt

Committee Member 1

Bridget Melton

Committee Member 2

Emily Langford

Abstract

The purpose of this study was to test the validity of the Polar Verity Sense optical armband and iPhone accelerometer (Kubois seismocardiography, SCG) against the Polar H10 across different body positions (for both devices) and measurement durations (for Verity Sense only) while accounting for skin pigmentation. Healthy young adults (n = 46) participated in simultaneous recordings in the supine, seated, and standing positions using the Kubios mobile application on separate devices. Verity Sense measurements were collected for both 1‑ and 5‑min durations, whereas accelerometer measures were 1 min. Skin pigmentation was quantified with the melanin index (M-index). For resting heart rate (RHR), both the Verity Sense and SCG demonstrated excellent agreement with the H10 across all positions, with mean biases ≤0.3 bpm, narrow 95% limits of agreement (LOA) and near‑perfect concordance (CCC = 0.99). For RMSSD, Verity Sense accuracy was position-dependent and similar between 1- and 5-min recordings. Verity Sense systematically overestimated RMSSD, with median biases ranging from 1–4 ms. Difference scores were non-normal across positions, resulting in asymmetric nonparametric LOA that widened substantially from supine to seated and standing positions. Relative agreement worsened with increasingly upright posture (CCC = 0.78–0.96), while absolute error was consistently poor (MAPE ≥21%). In contrast, SCG demonstrated minimal RMSSD bias (≤0.7 ms), moderate-to-near-perfect concordance (CCC = 0.94–0.98), and lower absolute error (MAPE = 7.3–10.7%). Although supine SCG RMSSD differences were also non-normal with asymmetric LOA, agreement remained superior to the Verity Sense. Melanin index was not associated with Verity Sense RMSSD error in the supine position, but moderate positive associations were observed in seated (r = 0.319, p = 0.045) and standing (r = 0.332, p = 0.042) 1-min recordings and standing 5-min recordings (r = 0.414, p = 0.011), indicating greater RMSSD error among participants with higher melanin levels during upright measurements. Overall, Verity Sense and SCG appear valid for RHR monitoring, whereas iPhone SCG may be a better alternative to the H10 than the Verity Sense for field-based RMSSD assessment.

Research Data and Supplementary Material

Yes

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