{
  "cutoff": "2026-10-13",
  "note": "Selected publication milestones, not an exhaustive history or discovery priority claim.",
  "milestones": [
    {
      "pmid": "2072834",
      "year": "1991",
      "title": "Exercise training below and above the lactate threshold in the elderly.",
      "doi": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/2072834/",
      "interpretation": "1991 a small older-adult controlled study reports measured-VO2max benefit from training below measured lactate threshold."
    },
    {
      "pmid": "1727835",
      "year": "1992",
      "title": "Low to moderate intensity endurance training in healthy older adults: physiological responses after four months.",
      "doi": "10.1111/j.1532-5415.1992.tb01820.x",
      "url": "https://pubmed.ncbi.nlm.nih.gov/1727835/",
      "interpretation": "1992 a larger healthy-older-adult attention-controlled trial establishes conventional moderate-cycling fitness gains without verifying individual below-VT1 exposure."
    },
    {
      "pmid": "10484570",
      "year": "1999",
      "title": "Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study.",
      "doi": "10.1152/jappl.1999.87.3.1003",
      "url": "https://pubmed.ncbi.nlm.nih.gov/10484570/",
      "interpretation": "1999 HERITAGE documents substantial variation and familial resemblance in training-associated maximal-oxygen-uptake gain."
    },
    {
      "pmid": "11719894",
      "year": "2001",
      "title": "Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study.",
      "doi": "10.1055/s-2001-18522",
      "url": "https://pubmed.ncbi.nlm.nih.gov/11719894/",
      "interpretation": "2001 HERITAGE retrospectively relates achieved intensity to measured threshold adaptation; maximal-VO2 change is not explained by initial position relative to VT."
    },
    {
      "pmid": "17213964",
      "year": "2007",
      "title": "Effectiveness of low-intensity endurance training.",
      "doi": "10.1055/s-2006-924037",
      "url": "https://pubmed.ncbi.nlm.nih.gov/17213964/",
      "interpretation": "2007 energy-matched low and moderate exercise gives similar maximal-fitness changes but different threshold responses and test-effort caveats."
    },
    {
      "pmid": "18580415",
      "year": "2008",
      "title": "Effect of intensity of aerobic training on VO2max.",
      "doi": "10.1249/MSS.0b013e31816c4839",
      "url": "https://pubmed.ncbi.nlm.nih.gov/18580415/",
      "interpretation": "2008 a volume-controlled randomized intensity trial finds greater VO2max improvements at higher intensities under relative-reserve prescriptions."
    },
    {
      "pmid": "23264537",
      "year": "2013",
      "title": "Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists.",
      "doi": "10.1152/japplphysiol.00652.2012",
      "url": "https://pubmed.ncbi.nlm.nih.gov/23264537/",
      "interpretation": "2013 polarized cycling improves selected performance measures without mitochondrial-enzyme change, separating functional adaptation from a uniform marker account."
    },
    {
      "pmid": "26146564",
      "year": "2015",
      "title": "Is a threshold-based model a superior method to the relative percent concept for establishing individual exercise intensity? a randomized controlled trial.",
      "doi": "10.1186/s13102-015-0011-z",
      "url": "https://pubmed.ncbi.nlm.nih.gov/26146564/",
      "interpretation": "2015 individualized VT1/VT2 exercise prescription improves fitness more than relative heart-rate-reserve prescription, while mixed-zone exposure requires explicit separation."
    },
    {
      "pmid": "30646252",
      "year": "2018",
      "title": "Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing.",
      "doi": "10.1001/jamanetworkopen.2018.3605",
      "url": "https://pubmed.ncbi.nlm.nih.gov/30646252/",
      "interpretation": "2018 a large clinical treadmill cohort strengthens fitness prognosis but does not identify a mortality mediator."
    },
    {
      "pmid": "33028588",
      "year": "2020",
      "title": "Effect of exercise training for five years on all cause mortality in older adults-the Generation 100 study: randomised controlled trial.",
      "doi": "10.1136/bmj.m3485",
      "url": "https://pubmed.ncbi.nlm.nih.gov/33028588/",
      "interpretation": "2020 Generation100 randomizes long-term exercise against activity guidelines and finds a combined mortality null with modest fitness separation and crossover."
    },
    {
      "pmid": "38376995",
      "year": "2024",
      "title": "Heavy-, Severe-, and Extreme-, but Not Moderate-Intensity Exercise Increase V̇o 2max and Thresholds after 6 wk of Training.",
      "doi": "10.1249/MSS.0000000000003406",
      "url": "https://pubmed.ncbi.nlm.nih.gov/38376995/",
      "interpretation": "2024 a randomized individualized-domain trial finds no significant six-week moderate-domain fitness advantage versus control, mapping a boundary to universal low-domain benefit."
    },
    {
      "pmid": "39797066",
      "year": "2025",
      "title": "Validation of Aerobic Capacity (VO2max) and Pulse Oximetry in Wearable Technology.",
      "doi": "10.3390/s25010275",
      "url": "https://pubmed.ncbi.nlm.nih.gov/39797066/",
      "interpretation": "2025 model-specific Garmin validation illustrates relatively favourable fitness prediction alongside poor oxygen-saturation concordance."
    },
    {
      "pmid": "38864459",
      "year": "2025",
      "title": "Cardiorespiratory Fitness, Body Composition, Diabetes, and Longevity: A 2-Sample Mendelian Randomization Study.",
      "doi": "10.1210/clinem/dgae393",
      "url": "https://pubmed.ncbi.nlm.nih.gov/38864459/",
      "interpretation": "2025 fitness-longevity Mendelian randomization reports no genetically predicted VO2max association, challenging isolated causal interpretation of prognosis."
    },
    {
      "pmid": "40198065",
      "year": "2025",
      "title": "Effects of Different Training Intensity Distributions on Endurance Capacity in Breast and Prostate Cancer Survivors: A Randomized Controlled Trial.",
      "doi": "10.1002/ejsc.12287",
      "url": "https://pubmed.ncbi.nlm.nih.gov/40198065/",
      "interpretation": "2025 isocaloric randomized training in cancer survivors yields similar fitness gains while planned polarized exposure is not achieved."
    },
    {
      "pmid": "42560532",
      "year": "2026",
      "title": "The effectiveness of polarized versus high-intensity training in moderately trained cyclists: a randomized parallel-design study.",
      "doi": "10.1007/s00421-026-06380-w",
      "url": "https://pubmed.ncbi.nlm.nih.gov/42560532/",
      "interpretation": "2026 adding low-domain volume to intervals produces no detected additional six-week performance benefit in a small trained cohort."
    },
    {
      "pmid": "42743109",
      "year": "2026",
      "title": "The accuracy of VO2 max, heart rate and energy expenditure measurements from Google Pixel Watch 3.",
      "doi": "10.1371/journal.pone.0356808",
      "url": "https://pubmed.ncbi.nlm.nih.gov/42743109/",
      "interpretation": "2026 Pixel Watch3 validation finds low mean VO2max bias but wide individual agreement, limiting use for small clinical changes."
    }
  ],
  "gaps": [
    "Replication of exclusive below-first-threshold training against no added training with modern measurement and transparent older-study methods",
    "A reproducible definition linking popular five-zone labels with the three-domain first-threshold boundary",
    "Dose, progression, adherence and disease boundaries specified before outcomes rather than by responding subgroups",
    "An isolated oxidative mediator instead of parallel biomarker change",
    "Mortality mediation distinct from prognosis, disease-specific genetics and broad exercise benefit",
    "Individual wearable agreement and detectable change across hardware, algorithms, exercise modes and clinical cohorts"
  ],
  "decisive_experiment": "Randomize baseline-defined sedentary and stable clinical adult strata to exclusive measured-below-LT1 training, volume-matched above-LT1 training or attention control for twelve weeks. Determine LT1/VT1 with preregistered algorithms, repeat threshold testing as fitness changes, record achieved exposure and adherence, and blind direct-gas-exchange maximal-test adjudication. Add predefined skeletal-muscle oxidative measurements as candidate mediators without asserting them necessary solely because they correlate."
}