{
  "abstract": "We compared the effects of a 6-day high-intensity interval training (HIT) microcycle followed by a 5-day active recovery period (HITblock) with a time-matched period of continued regular training (REG) on endurance performance in well-trained female cross-country skiers and biathletes. Seventeen athletes (maximal oxygen consumption ( V˙O2max ): 55.1 (5.2) mL·min⁻¹ kg⁻¹) were assigned to either HITblock or REG. No differences in training volume or intensity were observed between the groups during the 4 weeks preceding the intervention. During the intervention, HITblock completed five HIT sessions over 6 days (6 × 5-min work intervals; target rate of perceived exertion:17-18), with increased HIT replacing part of their habitual training and thereby reducing overall training load, whereas REG continued habitual training, including 3-4 moderate- or high-intensity interval sessions. Endurance performance was assessed during roller ski skating and included 15-min time-trial average velocity (velocity15-min), velocity at 4 mmol·L⁻¹ blood lactate (velocity4mmol), and velocity during the final minute of incremental V˙O2max testing ( velocityV˙O2max ). HITblock demonstrated greater improvements than REG in velocityV˙O2max (3.6 (2.1)% versus 1.2 (1.6)%, p = 0.024) and velocity4mmol (4.4 (2.9)% versus 0.0 (4.4)%, p = 0.023), whereas changes in velocity15-min did not differ between groups (5.4 (5.0)% versus 1.3 (3.4)%, p = 0.083). An exploratory composite performance index combining these outcomes demonstrated superior improvements in HITblock compared with REG (4.5 (2.8)% versus 0.9 (2.6)%, p = 0.017). These findings indicate that a 6-day HIT microcycle followed by a 5-day active recovery period is associated with greater improvements in selected endurance performance indicators compared with continued regular training in well-trained female cross-country skiers and biathletes.",
  "abstract_shown": true,
  "affiliations": [
    "Section for Health and Exercise Physiology, University of Inland Norway, Lillehammer, Norway.",
    "School of Sport Science, UiT The Arctic University of Norway, Tromsø, Norway."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Anders Sørensen"
    },
    {
      "affs": [
        0
      ],
      "name": "Ingvill Urianstad Odden",
      "orcid": "0009-0005-6139-6859"
    },
    {
      "affs": [
        0
      ],
      "name": "Anne Mette Rustaden",
      "orcid": "0000-0003-3696-4402"
    },
    {
      "affs": [
        0
      ],
      "name": "Håvard Nygaard",
      "orcid": "0000-0002-7401-5323"
    },
    {
      "affs": [
        0
      ],
      "name": "Joar Hansen"
    },
    {
      "affs": [
        1
      ],
      "name": "Øyvind Sandbakk",
      "orcid": "0000-0002-9014-5152"
    },
    {
      "affs": [
        0
      ],
      "name": "Tomas Urianstad Odden",
      "orcid": "0000-0001-6998-1335"
    },
    {
      "affs": [
        0
      ],
      "name": "Bent R Rønnestad",
      "orcid": "0000-0002-6907-1347"
    },
    {
      "affs": [
        0
      ],
      "name": "Knut Sindre Mølmen",
      "orcid": "0000-0001-8924-6848"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7y49f51frqp9b.bib",
  "cited_by": 0,
  "doi": "10.1002/ejsc.70276",
  "fulltext_url": "https://europepmc.org/articles/PMC13720754",
  "id": "7y49f51frqp9b",
  "issns": [
    "1746-1391",
    "1536-7290"
  ],
  "landing_url": "https://europepmc.org/article/MED/42960553",
  "language": "eng",
  "licence": "CC-BY-NC",
  "licence_label": "CC BY-NC",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Original Paper"
    ],
    [
      "openalex",
      "2732|Sports Performance and Training"
    ]
  ],
  "openalex": "W7224811476",
  "pdf_url": "https://europepmc.org/articles/PMC13720754?pdf=render",
  "pmcid": "PMC13720754",
  "pmid": "42960553",
  "published": "2026-10-30",
  "publisher": "Wiley",
  "ris": "https://research.draconitic.com/paper/7y49f51frqp9b.ris",
  "sources": [
    {
      "first_seen": "2026-11-01T00:20:50Z",
      "native_id": "MED:42960553",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42960553"
    },
    {
      "first_seen": "2026-11-03T12:21:34Z",
      "native_id": "PMC13720754",
      "source": "pmc",
      "url": "https://doi.org/10.1002/ejsc.70276"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2732|Sports Performance and Training",
      "subfield": "surgery"
    }
  ],
  "title": "A Six-Day High-Intensity Interval Training Microcycle Improves Selected Indicators of Endurance Performance in Well-Trained Female Cross-Country Skiers and Biathletes.",
  "title_text": "A Six-Day High-Intensity Interval Training Microcycle Improves Selected Indicators of Endurance Performance in Well-Trained Female Cross-Country Skiers and Biathletes.",
  "type": "peer-reviewed",
  "updated_at": "2026-11-03T12:21:34Z",
  "url": "https://research.draconitic.com/paper/7y49f51frqp9b",
  "venue": "European journal of sport science",
  "versions": []
}