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Paperdoi:10.3390/s24196220

The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024)

Venue listed2024Added Nov 6, 2026

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Authors: Ben O'Grady, Rory Lambe, Maximus Baldwin, Tara Acheson, Cailbhe Doherty (UCD)

Sensors 24(19):6220, published 2024-09-26

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CC BY 4.0

TL;DR

Cohort: 39 healthy adults; 316 paired morning 5-min supine recordings over 7–14 days (home). Devices: Apple Watch Series 9 or Ultra 2 (pooled; shared 3rd-gen optical sensor) via Breathe app SDNN; reference Polar H10 + Kubios. RHR: bias −0.08 bpm, MAE 3.73 bpm, MAPE 5.91%.

  • Form factor: wrist

Abstract

The widespread use of wearable devices has enabled continuous monitoring of biometric data, including heart rate variability (HRV) and resting heart rate (RHR). However, the validity of these measurements, particularly from consumer devices like Apple Watch, remains underexplored. This study aimed to validate HRV measurements obtained from Apple Watch Series 9 and Ultra 2 against the Polar H10 chest strap paired with the Kubios HRV software, which together served as the reference standard. A prospective cohort of 39 healthy adults provided 316 HRV measurements over a 14-day period. Generalized Estimating Equations were used to assess the difference in HRV between devices, accounting for repeated measures. Apple Watch tended to underestimate HRV by an average of 8.31 ms compared to the Polar H10 (p = 0.025), with a mean absolute percentage error (MAPE) of 28.88% and a mean absolute error (MAE) of 20.46 ms. The study found no significant impact of RHR discrepancies on HRV differences (p = 0.156), with RHR showing a mean difference of −0.08 bpm, an MAPE of 5.91%, and an MAE of 3.73 bpm. Equivalence testing indicated that the HRV measurements from Apple Watch did not fall within the pre-specified equivalence margin of ±10 ms. Despite accurate RHR measurements, these findings underscore the need for improved HRV algorithms in consumer wearables and caution in interpreting HRV data for clinical or performance monitoring.

Verbatim from the publisher's DOI record (opens in a new tab) · Publisher licence: https://creativecommons.org/licenses/by/4.0/

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Tasks & signals

Signals

PPGHRV

Devices

Apple Watch Series 9+Apple Watch UltraPolar H10

Keywords

ValidationSDNNRHRPolar H10Validation Index

How it works

How Method works: Setup → Method → TargetSetup: Signals (ppg-hr, hrv); Form factor (wrist). Method: Method.SetupSignals: ppg-hr, hrvSignalsppg-hr, hrvForm factor: wristForm factorwristMethodMethod

Cite this paper

Cite this paper with the fields recorded here. Check it against the publisher before submitting.

O'Grady, B., Lambe, R., Baldwin, M., Acheson, T., & Doherty, C. (2024). The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024). Sensors, 24(19), 6220. https://doi.org/10.3390/s24196220
O'Grady, Ben, Rory Lambe, Maximus Baldwin, Tara Acheson, and Cailbhe Doherty. 2024. "The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024)." Sensors 24 (19): 6220. https://doi.org/10.3390/s24196220.
O'Grady, B., Lambe, R., Baldwin, M., Acheson, T. and Doherty, C. (2024) 'The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024)', Sensors, 24(19), p. 6220. doi: 10.3390/s24196220.
O'Grady, Ben, et al. "The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024)." Sensors, vol. 24, no. 19, 2024, p. 6220. https://doi.org/10.3390/s24196220.
B. O'Grady, R. Lambe, M. Baldwin, T. Acheson, and C. Doherty, "The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024)," Sensors, vol. 24, no. 19, p. 6220, 2024, doi: 10.3390/s24196220.
@article{ogrady2024validity,
  title         = {{The Validity of Apple Watch Series 9 and Ultra 2 for Serial Measurements of Heart Rate Variability and Resting Heart Rate (O'Grady … Doherty; Sensors 2024)}},
  author        = {O'Grady, Ben and Lambe, Rory and Baldwin, Maximus and Acheson, Tara and Doherty, Cailbhe},
  year          = {2024},
  journal       = {Sensors},
  volume        = {24},
  number        = {19},
  pages         = {6220},
  doi           = {10.3390/s24196220}
}

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