A Six-Day High-Intensity Interval Training Microcycle Improves Selected Indicators of Endurance Performance in Well-Trained Female Cross-Country Skiers and Biathletes.
- 1Section for Health and Exercise Physiology, University of Inland Norway, Lillehammer, Norway.
- 2School of Sport Science, UiT The Arctic University of Norway, Tromsø, Norway.
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.
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BibTeX
@article{sorensen2026sixday,
title = {{A Six-Day High-Intensity Interval Training Microcycle Improves Selected Indicators of Endurance Performance in Well-Trained Female Cross-Country Skiers and Biathletes.}},
author = {Anders Sørensen and Ingvill Urianstad Odden and Anne Mette Rustaden and Håvard Nygaard and Joar Hansen and Øyvind Sandbakk and Tomas Urianstad Odden and Bent R Rønnestad and Knut Sindre Mølmen},
journal = {European journal of sport science},
year = {2026},
month = oct,
doi = {10.1002/ejsc.70276},
url = {https://europepmc.org/article/MED/42960553},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - A Six-Day High-Intensity Interval Training Microcycle Improves Selected Indicators of Endurance Performance in Well-Trained Female Cross-Country Skiers and Biathletes.
AU - Anders Sørensen
AU - Ingvill Urianstad Odden
AU - Anne Mette Rustaden
AU - Håvard Nygaard
AU - Joar Hansen
AU - Øyvind Sandbakk
AU - Tomas Urianstad Odden
AU - Bent R Rønnestad
AU - Knut Sindre Mølmen
PY - 2026
DA - 2026/10/30
JO - European journal of sport science
DO - 10.1002/ejsc.70276
UR - https://europepmc.org/article/MED/42960553
AB - 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.
SN - 1746-1391
SN - 1536-7290
ER -