{
  "schemaVersion": 1,
  "capturedAt": "2026-09-14T11:37:40.854Z",
  "sha256": "88086bb16014125c1fd7b69205dec67029aa477ab93b5d81bfd8e0644b16873b",
  "work": {
    "id": "TAP-RDN-0018",
    "kind": "note",
    "key": "billman-2013",
    "locale": "en",
    "path": "/research/billman-2013/",
    "title": "TAP reading note: The LF/HF ratio does not accurately measure cardiac sympatho-vagal balance",
    "description": "Billman challenges the assumptions behind interpreting LF/HF as cardiac sympathetic–vagal balance. Both frequency components have mixed influences, and different physiological changes can produce similar ratios.",
    "rights": "© The Allostasis Project. All rights reserved. Reproduction or adaptation requires separate permission, subject to applicable legal exceptions.",
    "version": "0.1",
    "updatedAt": "2026-09-14",
    "editorial": {
      "contentType": "evidence-review",
      "reviewState": "draft",
      "reviewedAt": null,
      "reviewedVersion": null,
      "updatedAt": "2026-09-14",
      "version": "0.1",
      "author": null,
      "reviewer": null,
      "revisions": []
    },
    "original": {
      "id": "billman-2013",
      "title": "The LF/HF ratio does not accurately measure cardiac sympatho-vagal balance",
      "authors": "George E. Billman",
      "journal": "Frontiers in Physiology",
      "year": "2013",
      "url": "https://doi.org/10.3389/fphys.2013.00026",
      "doi": "10.3389/fphys.2013.00026",
      "pmid": "23431279"
    },
    "references": [
      {
        "id": "billman-2013",
        "title": "The LF/HF ratio does not accurately measure cardiac sympatho-vagal balance",
        "authors": "George E. Billman",
        "journal": "Frontiers in Physiology",
        "year": "2013",
        "url": "https://doi.org/10.3389/fphys.2013.00026",
        "doi": "10.3389/fphys.2013.00026",
        "pmid": "23431279"
      }
    ],
    "sections": [
      {
        "id": "finding",
        "title": "What the study found",
        "paragraphs": [
          "Billman challenges the assumptions behind interpreting LF/HF as cardiac sympathetic–vagal balance. Both frequency components have mixed influences, and different physiological changes can produce similar ratios."
        ]
      },
      {
        "id": "limits",
        "title": "Scope & limitations",
        "paragraphs": [
          "Methodological opinion drawing on physiological experiments and mathematical examples; no new trial sample.",
          "The critique concerns a specific interpretation of LF/HF. It does not make every HRV measure useless, nor does it validate a replacement stress or recovery score."
        ]
      },
      {
        "id": "sample",
        "title": "Population & sample",
        "paragraphs": [
          "Methodological opinion drawing on physiological experiments and mathematical examples; no new trial sample."
        ]
      },
      {
        "id": "exposure",
        "title": "Exposure or intervention",
        "paragraphs": [
          "Assumptions connecting low- and high-frequency HRV components with autonomic activity."
        ]
      },
      {
        "id": "outcomes",
        "title": "Outcomes",
        "paragraphs": [
          "Validity of LF/HF interpretation, including non-linear autonomic interactions and respiratory influences."
        ]
      },
      {
        "id": "duration",
        "title": "Time frame",
        "paragraphs": [
          "Methodological discussion published in 2013; examples span several experimental contexts."
        ]
      },
      {
        "id": "funding",
        "title": "Research funding",
        "paragraphs": [
          "Not yet checked against the full publication."
        ]
      },
      {
        "id": "conflicts",
        "title": "Research conflicts of interest",
        "paragraphs": [
          "Not yet checked against the full publication."
        ]
      },
      {
        "id": "basis",
        "title": "Reading scope",
        "paragraphs": [
          "Based on the publication’s text, including Main text: assumptions, physiological examples and ratio interpretation. This reading note has not undergone independent scientific review."
        ]
      }
    ],
    "type": "RDN"
  }
}