AUTHOR=Karlsen Trine , Solli Guro Strøm , Samdal Svein Tore , Sandbakk Øyvind TITLE=Intensity Control During Block-Periodized High-Intensity Training: Heart Rate and Lactate Concentration During Three Annual Seasons in World-Class Cross-Country Skiers JOURNAL=Frontiers in Sports and Active Living VOLUME=2 YEAR=2020 URL=https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2020.549407 DOI=10.3389/fspor.2020.549407 ISSN=2624-9367 ABSTRACT=

Purpose: To describe heart rate (HR) and blood lactate (Bla⁻) responses during high-intensity interval training (HIT) in a long-term block-periodized HIT regimen in world-class cross-country (XC) skiers.

Methods: Data were collected in 14 world-class female XC skiers (aged 25 ± 5 years; body mass, 60.4 ± 6.5 kg; and maximal HR, 194 ± 8 beats · min⁻¹) throughout three entire seasons. The HR and Bla⁻ values were determined at the end of 572 intervals performed during 63 sessions and 17 HIT blocks utilizing different exercise modes: running, running with poles, and skiing (on-snow and roller ski) with classic and skating techniques.

Results: The mean HR was 91 ± 3% of HR_max with a corresponding Bla⁻ of 7.3 ± 2.1 mmol · L⁻¹. The average HR and Bla⁻ values were relatively similar across the different exercise modes, except for a lower HR (~90 vs. 92% of HR_max) for on-snow and roller ski classical skiing and lower Bla⁻ values (5.9 vs. 7.0–7.8 mmol · L⁻¹) for on-snow classical skiing compared to the other modes, both P < 0.05. An increase in HR and Bla⁻ was observed from interval working periods 1 to 3 (90–92% of HR_max and 6.5–7.7 mmol · L⁻¹) and further from 3 to 5 (92–93% of HR_max and 7.7–9.0 mmol · L⁻¹), all P < 0.05.

Conclusions: We describe long-term use of HIT-block periodization among world-class XC skiers who achieved target HR and Bla⁻ levels in all six exercise modes employed. According to athletes and coaches, the key to successful blocks was intensity control to allow for high-quality HIT sessions throughout the entire HIT block.