Cited by 229Heart Rate Variability and Autonomic ControlNon-Invasive Vital Sign MonitoringPhysical Activity and Health

The DOI matches its Crossref record; 31 of the 32 references it cites were found in a registry or an index.

Heart rate variability with photoplethysmography in 8 million individuals: a cross-sectional study

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Abstract

Background Heart rate variability, or the variation in the time interval between consecutive heart beats, is a non-invasive dynamic metric of the autonomic nervous system and an independent risk factor for cardiovascular death. Consumer wrist-worn tracking devices using photoplethysmography, such as Fitbit, now provide the unique potential of continuously measuring surrogates of sympathetic and parasympathetic nervous system activity through the analysis of interbeat intervals. We aimed to leverage wrist-worn trackers to derive and describe diverse measures of cardiac autonomic function among Fitbit device users. Methods In this cross-sectional study, we collected interbeat interval data that are sent to a central database from Fitbit devices during a randomly selected 24 h period. Age, sex, body-mass index, and steps per day in the 90 days preceding the measurement were extracted. Interbeat interval data were cleaned and heart rate variability features were computed. We analysed heart rate variability metrics across the time (measured via the root mean square of successive RR interval differences [RMSSD] and SD of the RR interval [SDRR]), frequency (measured by high-frequency and low-frequency power), and graphical (measured by Poincare plots) domains. We considered 5 min windows for the time and frequency domain metrics and 60 min measurements for graphical domain metrics. Data from participants were analysed to establish the correlation between heart rate variability metrics and age, sex, time of day, and physical activity. We also determined benchmarks for heart rate variability (HRV) metrics among the users. Findings We included data from 8 203 261 Fitbit users, collected on Sept 1, 2018. HRV metrics decrease with age, and parasympathetic function declines faster than sympathetic function. We observe a strong diurnal variation in the heart rate variability. SDRR, low-frequency power, and Poincare S 2 show a significant variation with sex, whereas such a difference is not seen with RMSSD, high-frequency power, and Poincare S 1 . For males, when measured from 0600 h to 0700 h, the mean low-frequency power decreased by a factor of 66·5% and high-frequency power decreased by a factor of 82·0% from the age of 20 years to 60 years. For females, the equivalent factors were 69·3% and 80·9%, respectively. Comparing low-frequency power between males and females at the ages of 40–41 years, measured from 0600 h to 0700 h, we found excess power in males, with a Cohen's d effect size of 0·33. For high-frequency power, the equivalent effect size was −0·04. Increased daily physical activity, across age and sex, was highly correlated with improvement in diverse measures of heart rate variability in a dose-dependent manner. We provide benchmark tables for RMSSD, SDRR, high and low frequency powers, and Poincare S 1 and S 2 , separately for different ages and sex and computed at two times of the day. Interpretation Diverse metrics of cardiac autonomic health can be derived from wrist-worn trackers. Empirical distributions of heart rate variability can potentially be used as a framework for individual-level interpretation. Increased physical activity might yield improvement in heart rate variability and requires prospective trials for confirmation. Funding Fitbit.

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Crossref · 10.1016/s2589-7500(20)30246-6

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  1. Irurzun, 2018, Scaling behaviour in the heart rate variability characteristics with age, arXiv

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Metadata

Authors
Natarajan, A., Pantelopoulos, A., Emir-Farinas, H., & Natarajan, P.
Affiliations
  • Fitbit (United States) (US)
  • Broad Institute (US)
Corresponding author
Natarajan, Pradeep
Venue
The Lancet Digital Health
Publisher
Elsevier BV
Published
2020-12
Volume
2
Issue
12
Pages
e650-e657
ISSN
2589-7500 (ISSN-L)
OpenAlex
W3107602031
Cited by
229
References
32
Citations by year
2026: 44 · 2025: 39 · 2024: 41 · 2023: 52 · 2022: 29 · 2021: 22 · 2020: 2
FWCI
16.23
Type
journal article
Language
en
Open access
Locations
  • The Lancet Digital Health (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Topics
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Heart Rate Variability and Autonomic Control
  • Physical Sciences › Engineering › Biomedical Engineering › Non-Invasive Vital Sign Monitoring
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Physical Activity and Health
Keywords
heart rate variability, photoplethysmography, Fitbit, autonomic nervous system, parasympathetic function, sympathetic function, diurnal variation, sex differences, age-related decline, physical activity, Poincaré plot, low-frequency power, cardiovascular risk, wearable health devices, RMSSD, high-frequency power, cardiovascular mortality risk factors
MeSH terms
Wearable Electronic Devices, Adolescent, Adult, Age Factors, Aged, Cardiovascular Diseases, Cross-Sectional Studies, Female, Heart Rate, Humans, Male, Middle Aged, Parasympathetic Nervous System, Prospective Studies, Sex Factors, Sympathetic Nervous System, Exercise, Photoplethysmography, Telemedicine, Monitoring, Ambulatory, Young Adult

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