{
  "name": "Zonometry research library",
  "updated": "2026-09-21",
  "articles": [
    {
      "title": "The science behind the balance",
      "description": "A guide to Seiler’s three zones, polarized and pyramidal training, Apple Watch heart-rate zones, and what an 80/20 training mix really measures.",
      "url": "https://zonometry.com/science/",
      "text_url": "https://zonometry.com/science/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 826,
      "sections": [
        {
          "id": "start-here",
          "title": "Start with the question you have",
          "url": "https://zonometry.com/science/#start-here"
        },
        {
          "id": "three-questions",
          "title": "Three questions behind every percentage",
          "url": "https://zonometry.com/science/#three-questions"
        },
        {
          "id": "evidence",
          "title": "What the evidence actually says",
          "url": "https://zonometry.com/science/#evidence"
        },
        {
          "id": "terms",
          "title": "A small vocabulary that prevents big misunderstandings",
          "url": "https://zonometry.com/science/#terms"
        },
        {
          "id": "app",
          "title": "See your training at a glance",
          "url": "https://zonometry.com/science/#app"
        },
        {
          "id": "sources",
          "title": "Sources and further reading",
          "url": "https://zonometry.com/science/#sources"
        }
      ],
      "sources": [
        "https://doi.org/10.3389/fphys.2014.00033",
        "https://doi.org/10.3389/fphys.2015.00295",
        "https://doi.org/10.1007/s40279-024-02034-z",
        "https://pubmed.ncbi.nlm.nih.gov/39888556/",
        "https://www.youtube.com/watch?v=NPwyk9B0j-s"
      ]
    },
    {
      "title": "Three zones. Two thresholds. Your physiology.",
      "description": "Stephen Seiler’s training-zone presentation explained: physiological thresholds, three versus five zones, individual testing, and what it means for your watch.",
      "url": "https://zonometry.com/science/seiler-training-zones/",
      "text_url": "https://zonometry.com/science/seiler-training-zones/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 874,
      "sections": [
        {
          "id": "answer",
          "title": "What is Seiler’s three-zone model?",
          "url": "https://zonometry.com/science/seiler-training-zones/#answer"
        },
        {
          "id": "watch",
          "title": "Watch Seiler explain the framework",
          "url": "https://zonometry.com/science/seiler-training-zones/#watch"
        },
        {
          "id": "five-zones",
          "title": "Why have five zones if there are two thresholds?",
          "url": "https://zonometry.com/science/seiler-training-zones/#five-zones"
        },
        {
          "id": "thresholds",
          "title": "Thresholds are personal measurements",
          "url": "https://zonometry.com/science/seiler-training-zones/#thresholds"
        },
        {
          "id": "middle",
          "title": "Where moderate training fits",
          "url": "https://zonometry.com/science/seiler-training-zones/#middle"
        },
        {
          "id": "distribution",
          "title": "How the zones connect to 80/20",
          "url": "https://zonometry.com/science/seiler-training-zones/#distribution"
        },
        {
          "id": "apply",
          "title": "How to apply the model when reading your data",
          "url": "https://zonometry.com/science/seiler-training-zones/#apply"
        },
        {
          "id": "sources",
          "title": "Sources",
          "url": "https://zonometry.com/science/seiler-training-zones/#sources"
        }
      ],
      "sources": [
        "https://www.youtube.com/watch?v=NPwyk9B0j-s",
        "https://www.youtube.com/watch?v=NPwyk9B0j-s&t=23s",
        "https://www.youtube.com/watch?v=NPwyk9B0j-s&t=58s",
        "https://www.youtube.com/watch?v=NPwyk9B0j-s&t=160s",
        "https://www.youtube.com/watch?v=NPwyk9B0j-s&t=201s",
        "https://doi.org/10.3389/fphys.2015.00295",
        "https://sportsci.org/2009/ss.htm"
      ]
    },
    {
      "title": "Five watch zones. One clearer picture.",
      "description": "How Zonometry groups Apple Watch heart-rate zones into easy, moderate and hard, with a worked bpm example, custom boundaries, and data-coverage explanations.",
      "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/",
      "text_url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 850,
      "sections": [
        {
          "id": "mapping",
          "title": "How does Zonometry group Apple Watch zones?",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#mapping"
        },
        {
          "id": "apple-estimates",
          "title": "What does Apple estimate?",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#apple-estimates"
        },
        {
          "id": "worked-example",
          "title": "A worked example in beats per minute",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#worked-example"
        },
        {
          "id": "custom-boundaries",
          "title": "When to use custom boundaries",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#custom-boundaries"
        },
        {
          "id": "coverage",
          "title": "Why doesn’t zone time always equal workout time?",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#coverage"
        },
        {
          "id": "compare",
          "title": "How to compare the app with Fitness",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#compare"
        },
        {
          "id": "sources",
          "title": "Sources",
          "url": "https://zonometry.com/guides/apple-watch-heart-rate-zones/#sources"
        }
      ],
      "sources": [
        "https://support.apple.com/guide/watch/view-heart-rate-zones-apd897dccddf/watchos",
        "https://doi.org/10.3389/fphys.2015.00295"
      ]
    },
    {
      "title": "What does your training mix really mean?",
      "description": "Understand 80/20 training, sessions versus time in zones, polarized versus pyramidal distributions, and why one hard run can change your weekly balance.",
      "url": "https://zonometry.com/guides/training-distribution/",
      "text_url": "https://zonometry.com/guides/training-distribution/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 1178,
      "sections": [
        {
          "id": "answer",
          "title": "What does 80/20 training mean?",
          "url": "https://zonometry.com/guides/training-distribution/#answer"
        },
        {
          "id": "same-week",
          "title": "The same week, counted two ways",
          "url": "https://zonometry.com/guides/training-distribution/#same-week"
        },
        {
          "id": "workout",
          "title": "Why a hard session contains easy time",
          "url": "https://zonometry.com/guides/training-distribution/#workout"
        },
        {
          "id": "shapes",
          "title": "Polarized and pyramidal are different shapes",
          "url": "https://zonometry.com/guides/training-distribution/#shapes"
        },
        {
          "id": "evidence",
          "title": "What do comparisons of training methods show?",
          "url": "https://zonometry.com/guides/training-distribution/#evidence"
        },
        {
          "id": "period",
          "title": "An unfinished week is an unfinished story",
          "url": "https://zonometry.com/guides/training-distribution/#period"
        },
        {
          "id": "targets",
          "title": "Set targets that fit your training",
          "url": "https://zonometry.com/guides/training-distribution/#targets"
        },
        {
          "id": "checklist",
          "title": "Read a surprising mix in this order",
          "url": "https://zonometry.com/guides/training-distribution/#checklist"
        },
        {
          "id": "sources",
          "title": "Sources",
          "url": "https://zonometry.com/guides/training-distribution/#sources"
        }
      ],
      "sources": [
        "https://doi.org/10.3389/fphys.2015.00295",
        "https://doi.org/10.1007/s40279-024-02034-z",
        "https://doi.org/10.3389/fphys.2014.00033"
      ]
    },
    {
      "title": "The nine-week polarized training trial",
      "description": "A detailed reading of Stöggl and Sperlich’s 2014 trial: participants, four training groups, VO₂peak results, unequal volume, and practical limitations.",
      "url": "https://zonometry.com/science/polarized-training-2014/",
      "text_url": "https://zonometry.com/science/polarized-training-2014/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 723,
      "sections": [
        {
          "id": "finding",
          "title": "What did the study find?",
          "url": "https://zonometry.com/science/polarized-training-2014/#finding"
        },
        {
          "id": "design",
          "title": "Who trained, and how was the comparison made?",
          "url": "https://zonometry.com/science/polarized-training-2014/#design"
        },
        {
          "id": "programs",
          "title": "Four programs, not one isolated variable",
          "url": "https://zonometry.com/science/polarized-training-2014/#programs"
        },
        {
          "id": "outcomes",
          "title": "What improved, and what did those tests measure?",
          "url": "https://zonometry.com/science/polarized-training-2014/#outcomes"
        },
        {
          "id": "limits",
          "title": "What should temper the headline?",
          "url": "https://zonometry.com/science/polarized-training-2014/#limits"
        },
        {
          "id": "context",
          "title": "How does later research change the interpretation?",
          "url": "https://zonometry.com/science/polarized-training-2014/#context"
        },
        {
          "id": "sources",
          "title": "Sources",
          "url": "https://zonometry.com/science/polarized-training-2014/#sources"
        }
      ],
      "sources": [
        "https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2014.00033/full",
        "https://doi.org/10.3389/fphys.2014.00033",
        "https://creativecommons.org/licenses/by/4.0/"
      ]
    },
    {
      "title": "Polarized or pyramidal? Read the whole shape.",
      "description": "Stöggl and Sperlich’s 2015 review explained: what elite athletes actually do, why counting methods and seasons matter, and where the evidence stops.",
      "url": "https://zonometry.com/science/training-intensity-review-2015/",
      "text_url": "https://zonometry.com/science/training-intensity-review-2015/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 874,
      "sections": [
        {
          "id": "finding",
          "title": "What does the review add?",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#finding"
        },
        {
          "id": "design",
          "title": "What kind of paper is this?",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#design"
        },
        {
          "id": "shapes",
          "title": "Two ways to be mostly easy",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#shapes"
        },
        {
          "id": "seasons",
          "title": "Sport and season change the picture",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#seasons"
        },
        {
          "id": "measurement",
          "title": "Measurement can change the apparent distribution",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#measurement"
        },
        {
          "id": "evidence",
          "title": "Observation and intervention need different interpretations",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#evidence"
        },
        {
          "id": "limits",
          "title": "Where this review leaves uncertainty",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#limits"
        },
        {
          "id": "sources",
          "title": "Sources",
          "url": "https://zonometry.com/science/training-intensity-review-2015/#sources"
        }
      ],
      "sources": [
        "https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2015.00295/full",
        "https://doi.org/10.3389/fphys.2015.00295",
        "https://creativecommons.org/licenses/by/4.0/"
      ]
    },
    {
      "title": "Does polarized training come out ahead?",
      "description": "A visual guide to the 2024 polarized-training meta-analysis: 17 studies, 437 participants, effect sizes, confidence intervals, limitations, and newer evidence.",
      "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/",
      "text_url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/article.txt",
      "reviewed": "2026-09-21",
      "author": "Zonometry",
      "word_count": 824,
      "sections": [
        {
          "id": "finding",
          "title": "Is polarized training better?",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#finding"
        },
        {
          "id": "methods",
          "title": "What did the researchers compare?",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#methods"
        },
        {
          "id": "results",
          "title": "Four outcomes, four different estimates",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#results"
        },
        {
          "id": "subgroups",
          "title": "Who appeared to benefit most?",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#subgroups"
        },
        {
          "id": "limitations",
          "title": "What are the important limitations?",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#limitations"
        },
        {
          "id": "newer-evidence",
          "title": "What about research published later?",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#newer-evidence"
        },
        {
          "id": "app",
          "title": "What does this mean for your training?",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#app"
        },
        {
          "id": "sources",
          "title": "Sources",
          "url": "https://zonometry.com/science/polarized-training-meta-analysis-2024/#sources"
        }
      ],
      "sources": [
        "https://link.springer.com/article/10.1007/s40279-024-02034-z",
        "https://doi.org/10.1007/s40279-024-02034-z",
        "https://pubmed.ncbi.nlm.nih.gov/39888556/",
        "https://creativecommons.org/licenses/by/4.0/"
      ]
    }
  ]
}