ArticleSensors (Basel, Switzerland)2021
Wrist-Based Photoplethysmography Assessment of Heart Rate and Heart Rate Variability: Validation of WHOOP.
Article in Sensors (Basel, Switzerland), 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. It is linked to trial NCT07097168 (Evaluating Clinical Course in Coronary Artery Bypass Patients Using the WHOOP Fitness Band Heart Rate Variability Application.), which is not on this map. Cited by 42 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Evaluating Clinical Course in Coronary Artery Bypass Patients Using the WHOOP Fitness Band Heart Rate Variability Application.
Who cites it
42 citing papers in PubMed, 1 synthesis or guideline pooled it, 62 citations in OpenAlex.
- Accuracy of Photoplethysmography-Derived Pulse Rate Variability Compared with Electrocardiography-Derived Heart Rate Variability: A Systematic Review and Meta-Analysis.Sensors (Basel, Switzerland) · 2026Pooled it
- An examination into the mental and physical effects of a saffron extract (affron®) in recreationally-active adults: A randomized, double-blind, placebo-controlled study.Journal of the International Society of Sports Nutrition · 2022Trial
- Within-Athlete Associations Between WHOOP Activity Strain, Coach-Prescribed Training Objectives, and Session-RPE in an Elite Junior Swimmer: A Longitudinal Single-Case Study.Journal of functional morphology and kinesiology · 2026Article
- Guidelines for rigor and reproducibility of heart rate variability within human cardiovascular research.American journal of physiology. Heart and circulatory physiology · 2026Review
- Orthometria: Metric Fixation in Digital Health and a Framework for Responsible Use in High-Performance Sport.Sports medicine - open · 2026Article
- Exercise Training and Heart Rate Variability: A Guided Optimization of Cardiorespiratory Fitness in Cardiometabolic Disease.Current atherosclerosis reports · 2026Review
- Predicting Next Day Heart Rate Variability Based on Training Load in Cyclists Using Machine Learning.Sports (Basel, Switzerland) · 2026Article
- Wearable technologies in clinical trials for drug development: trends and emerging opportunities.Nature reviews. Drug discovery · 2026Review
- Multimodal clinical, sleep, and autonomic correlates across the depressive spectrum: a cross-sectional study.Frontiers in psychology · 2026Article
- Music-based emotional regulation and nutrition strategies for mental health support among medical student-athletes.Frontiers in nutrition · 2026Article
- Tracking the longitudinal course of physiologic and mental health functioning among individuals in substance use disorder treatment.Frontiers in psychiatry · 2026Article
- Preliminary field evaluation and exploratory external-association analysis of a modified wellness questionnaire for short-term monitoring in elite male water polo players.Frontiers in sports and active living · 2026Article
- Individual training prescribed by heart rate variability, heart rate and well-being scores in experienced cyclists.Scientific reports · 2025Article
- Holistically assessing dismounted warfighter military performance: bridging science and operational relevancy.BMJ military health · 2025Review
- Validation of nocturnal resting heart rate and heart rate variability in consumer wearables.Physiological reports · 2025Article
- Ultra-short-term heart rate variability using a photoplethysmography-based smartphone application: a TeleCheck-AF subanalysis.European heart journal. Digital health · 2025Article
- Biostrap Kairos Wristband Versus Electrocardiography for Resting Heart Rate Variability Assessment.Sensors (Basel, Switzerland) · 2025Article
- Assessment of autonomic function in patient with COVID-19 and other infectious diseases using a wearable smart band connected to a mobile application.Frontiers in psychiatry · 2025Article
- The Night-Time Sleep and Autonomic Activity of Male and Female Professional Road Cyclists Competing in the Tour de France and Tour de France Femmes.Sports medicine - open · 2024Article
- Tracking changes in autonomic function by coupled analysis of wavelet-based dispersion of heart rate variability and gastrointestinal symptom severity in individuals with hypermobile Ehlers-Danlos syndrome.Frontiers in neurology · 2024Article
Corrections and comments
- Erratum issued
Authors and funding
5 authors at 3 institutions in 1 country.
Funding
Abstract
Heart rate (HR) and HR variability (HRV) infer readiness to perform exercise in athletic populations. Technological advancements have facilitated HR and HRV quantification via photoplethysmography (PPG). This study evaluated the validity of WHOOP's PPG-derived HR and HRV against electrocardiogram-derived (ECG) measures. HR and HRV were assessed via WHOOP and ECG over 15 opportunities. WHOOP-derived pulse-to-pulse (PP) intervals were edited with WHOOP's proprietary filter, in addition to various filter strengths via Kubios HRV software. HR and HRV (Ln RMSSD) were quantified for each filter strength. Agreement was assessed via bias and limits of agreement (LOA), and contextualised using smallest worthwhile change (SWC) and coefficient of variation (CV). Regardless of filter strength, bias (≤0.39 ± 0.38%) and LOA (≤1.56%) in HR were lower than the CV (10-11%) and SWC (5-5.5%) for this parameter. For Ln RMSSD, bias (1.66 ± 1.80%) and LOA (±5.93%) were lowest for a 200 ms filter and WHOOP's proprietary filter, which approached or exceeded the CV (3-13%) and SWC (1.5-6.5%) for this parameter. Acceptable agreement was found between WHOOP- and ECG-derived HR. Bias and LOA in Ln RMSSD approached or exceeded the SWC/CV for this variable and should be interpreted against its own level of bias precision.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.