Intensity Control During Block-Periodized High-Intensity Training: Heart Rate and Lactate Concentration During Three Annual Seasons in World-Class Cross-Country Skiers

Purpose: To describe heart rate (HR) and blood lactate (Bla-) responses during high-intensity interval training (HIT) in a long-term block-periodized HIT regime in world-class cross-country (XC) skiers. Methods: Data were collected in 14 world-class female XC skiers (age: 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 HRmax 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 HRmax) 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<.05. An increase in HR and Bla- was observed from interval working periods 1 to 3 (90 to 92% of HRmax and 6.5 to 7.7 mmolL-1) and further from 3 to 5 (92 to 93% of HRmax and 7.7 to 9.0 mmolL-1), all P<.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.