University of Oulu

Hannu Kinnunen et al 2020 Physiol. Meas. 41 04NT01

Feasible assessment of recovery and cardiovascular health : accuracy of nocturnal HR and HRV assessed via ring PPG in comparison to medical grade ECG

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Author: Kinnunen, Hannu1,2; Rantanen, Aleksi2; Kenttä, Tuomas2,3;
Organizations: 1Optoelectronics and Measurement Techniques Research Group, University of Oulu, Oulu, Finland
2Oura Health Ltd, Oulu, Finland
3Research Unit of Internal Medicine, Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland
4Biomimetics and Intelligent Systems Group, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.8 MB)
Persistent link:
Language: English
Published: IOP Publishing, 2020
Publish Date: 2020-09-18


Objective: To validate the accuracy of the Oura ring in the quantification of resting heart rate (HR) and heart rate variability (HRV).

Background: Wearable devices have become comfortable, lightweight, and technologically advanced for assessing health behavior. As an example, the novel Oura ring integrates daily physical activity and nocturnal cardiovascular measurements. Ring users can follow their autonomic nervous system responses to their daily behavior based on nightly changes in HR and HRV, and adjust their behavior accordingly after self-reflection. As wearable photoplethysmogram (PPG) can be disrupted by several confounding influences, it is crucial to demonstrate the accuracy of ring measurements.

Approach: Nocturnal HR and HRV were assessed in 49 adults with simultaneous measurements from the Oura ring and the gold standard ECG measurement. Female and male participants with a wide age range (15—72 years) and physical activity status were included. Regression analysis between ECG and the ring outcomes was performed.

Main results: Very high agreement between the ring and ECG was observed for nightly average HR and HRV (r2 = 0.996 and 0.980, respectively) with a mean bias of −0.63 bpm and −1.2 ms. High agreement was also observed across 5 min segments within individual nights in (r2 = 0.869 ± 0.098 and 0.765 ± 0.178 in HR and HRV, respectively).

Significance: Present findings indicate high validity of the Oura ring in the assessment of nocturnal HR and HRV in healthy adults. The results show the utility of this miniaturised device as a lifestyle management tool in long-term settings. High quality PPG signal results prompt future studies utilizing ring PPG towards clinically relevant health outcomes.

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Series: Physiological measurement
ISSN: 0967-3334
ISSN-E: 1361-6579
ISSN-L: 0967-3334
Volume: 41
Issue: 4
Article number: 04NT01
DOI: 10.1088/1361-6579/ab840a
Type of Publication: A1 Journal article – refereed
Field of Science: 3111 Biomedicine
213 Electronic, automation and communications engineering, electronics
217 Medical engineering
Funding: This research was financially supported by Tauno Tönning foundation grant 20190151.
Copyright information: © 2020 Institute of Physics and Engineering in Medicine. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.