{
  "registry": "KnowYourPrime Evidence Registry",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Credit KnowYourPrime and link to the finding URL."
  },
  "fields": {
    "devices": "Devices this finding names, including models it says it does not cover. What was actually tested is in scope.applies_to; exclusions are in scope.does_not_cover.",
    "evidence": "Studies by role: anchor (the rating rests on it), conflicting, null_result, supporting.",
    "industry_ties": "Device-maker ties listed in Europe PMC metadata: author_affiliations names makers an author lists as an affiliation, funders names makers listed as funding. stated_ties holds ties a paper states only in its own conflict, funding or acknowledgement text, each read from that statement and worded to say only what it says. Sources are Europe PMC metadata, funding printed in the abstract, and those reviewed statements. An empty list means no tie was found there, not that the study is independent: many papers have no open full text to read. Metadata, not a judgment of the study. checked false means no Europe PMC metadata was available."
  },
  "id": "KYP-ER-0004",
  "version": "1.0",
  "reviewed": "2026-10-24",
  "url": "https://knowyourprime.com/evidence-chest-strap-hrv-accuracy",
  "title": "Chest Strap HRV Accuracy Against ECG",
  "question": "Is a chest-strap heart rate monitor as accurate as a clinical ECG for heart rate variability at rest?",
  "measurement": "Heart rate variability (HRV)",
  "devices": [
    "Polar H10",
    "Polar H7"
  ],
  "rating": {
    "label": "Established",
    "code": "established",
    "definition": "Strong, consistent evidence supports the claim.",
    "rule_version": "1.6",
    "rule_reasons": [
      "Anchor-grade evidence affirms the core relationship.",
      "Multiple supporting studies are consistent with the core relationship."
    ]
  },
  "conclusion": "Yes, at rest. Polar chest straps recorded HRV close enough to a clinical ECG to be interchangeable while lying, sitting or breathing slowly, and agreement fell away as exercise intensity rose.",
  "reasoning": [
    "A chest strap reads the heart's electrical signal, as an ECG does, rather than estimating beats from light at the wrist. That is why it is the usual reference when wrist and ring HRV are tested.",
    "Two independent studies of different Polar straps, each recording simultaneously against an ECG, affirm agreement at rest, and nothing in the evidence scored here contradicts it, so the rule rates the claim Established. The same evidence sets its limit: agreement degrades during harder exercise."
  ],
  "key_results": [
    {
      "text": "In 43 healthy adults, a Polar H10 matched a criterion ECG with concordance at or above 0.99 on every HRV metric, mean absolute percentage error below 1 percent and limits of agreement within -1.5 to 1.7 ms, across supine rest, paced breathing and standing.",
      "source": "doi:10.1016/j.autneu.2026.103447",
      "source_url": "https://doi.org/10.1016/j.autneu.2026.103447",
      "source_citation": "Blalock et al., Autonomic Neuroscience, 2026"
    },
    {
      "text": "In 67 men, a Polar H7 was interchangeable with ECG at rest, while agreement degraded as cycling intensity rose, most for high-frequency power, and was poorest in older, unfit participants with high trunk fat.",
      "source": "doi:10.3390/s21030902",
      "source_url": "https://doi.org/10.3390/s21030902",
      "source_citation": "Hernández-Vicente et al., Sensors, 2021"
    }
  ],
  "scope": {
    "applies_to": "Polar H10 and H7 chest straps at rest and in light activity, compared with simultaneous ECG.",
    "does_not_cover": "Other chest strap brands, which can differ (one low-cost strap agreed at rest and diverged during running); HRV during hard exercise; any health interpretation of the HRV number."
  },
  "limitations": [
    "Both anchor studies tested Polar straps; other brands need their own validation.",
    "Participants were healthy adults; agreement in people with arrhythmias is a separate question."
  ],
  "evidence": {
    "anchor": [
      {
        "key": "doi:10.1016/j.autneu.2026.103447",
        "title": "Validity of the Polar H10 for heart rate variability and cardiac autonomic reflex tests.",
        "first_author": "Blalock",
        "journal": "Autonomic neuroscience : basic & clinical",
        "year": 2026,
        "url": "https://doi.org/10.1016/j.autneu.2026.103447",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.3390/s21030902",
        "title": "Validity of the Polar H7 Heart Rate Sensor for Heart Rate Variability Analysis during Exercise in Different Age, Body Composition and Fitness Level Groups.",
        "first_author": "Hernández-Vicente",
        "journal": "Sensors (Basel, Switzerland)",
        "year": 2021,
        "url": "https://doi.org/10.3390/s21030902",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "supporting": [
      {
        "key": "doi:10.1123/ijspp.2025-0126",
        "title": "Limited Validity of the Low-Cost Coospo H808S Heart-Rate Monitor Compared to the Polar H10.",
        "first_author": "Protzen",
        "journal": "International journal of sports physiology and performance",
        "year": 2025,
        "url": "https://doi.org/10.1123/ijspp.2025-0126",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1123/ijspp.2019-0406",
        "title": "Validity of a Smartphone Application and Chest Strap for Recording RR Intervals at Rest in Athletes.",
        "first_author": "Pereira",
        "journal": "International journal of sports physiology and performance",
        "year": 2020,
        "url": "https://doi.org/10.1123/ijspp.2019-0406",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.2478/folmed-2018-0012",
        "title": "Can Wearable Devices Accurately Measure Heart Rate Variability? A Systematic Review.",
        "first_author": "Georgiou",
        "journal": "Folia medica",
        "year": 2019,
        "url": "https://doi.org/10.2478/folmed-2018-0012",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ]
  },
  "evidence_last_evaluated": "Oct 24, 2026",
  "rating_history": [
    {
      "date": "2026-09-29",
      "rating": "Established",
      "from": null,
      "rule_version": "1.6"
    }
  ],
  "versions": [
    {
      "version": "1.0",
      "date": "2026-10-24",
      "rating": "Established",
      "change": "First published."
    }
  ],
  "research_desk": "https://knowyourprime.com/research-desk-hrv#chest-strap-accuracy",
  "related_findings": [
    "https://knowyourprime.com/evidence-wearable-hrv-accuracy"
  ],
  "related_articles": [
    "https://knowyourprime.com/chest-strap-hrv-accuracy-vs-ecg",
    "https://knowyourprime.com/coospo-vs-polar-h10-hrv-accuracy"
  ],
  "methodology": "https://knowyourprime.com/methodology",
  "citation": "KnowYourPrime Evidence Registry, Finding KYP-ER-0004, version 1.0, reviewed 2026-10-24. https://knowyourprime.com/evidence-chest-strap-hrv-accuracy"
}