Choosing between intervals and steady-tempo endurance training is often a challenge for skiers planning their intensity sessions. Should the focus of intense training be on steady-tempo endurance workouts or various types of interval sessions? Or should a balanced approach be taken, combining both equally?

Research evidence mainly addresses the differences between intervals and steady-tempo workouts at the group level. However, there is little data on the individual suitability of intervals versus steady efforts. According to Vesterinen, the comparison between high-intensity interval training (HIIT) and steady-tempo workouts has been extensively studied, revealing some differences at the group level.

“High-intensity interval training is more effective for improving maximal oxygen uptake and performance. Studies have also shown significant individual variation in response to intense training. Some individuals see little improvement, while others progress significantly. There is very limited knowledge about why some people improve and others don’t. More research is needed to determine who benefits more from steady efforts versus intervals,” says Vesterinen.

In his doctoral dissertation, Vesterinen studied individual variability in the effectiveness of endurance training, comparing low-intensity, high-volume training with high-intensity training. Both groups contained individuals who developed well and those who did not.

“High-intensity training enhances maximal oxygen uptake and top-end attributes. When we analyzed what factors explained performance improvements in these endurance athletes, we found no connection with age or fitness level. The strongest predictor was heart rate variability at rest. Those who benefited most from high-intensity interval training had higher heart rate variability. In contrast, individuals with lower heart rate variability responded better to low-intensity training, as it provided sufficient stimulus without being too taxing. High-intensity training could be too demanding for them,” explains Vesterinen.

In high-intensity intervals, athletes can maintain higher effort levels for longer due to rest periods, making it easier to boost maximal performance compared to steady sessions. For sports involving bursts of speed, interval training may be more effective for enhancing performance.

“Steady efforts are more suitable for athletes preparing for long-distance events like marathons or long ski races,” says Vesterinen.

“For recreational athletes, steady tempo training is generally a solid endurance workout. However, more fit individuals may need more intense interval sessions.”

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Short Intervals for Modern Skiing

Recent Norwegian studies have compared short intervals to traditional longer ones.

“It’s often found that 3-5 minute maximal endurance intervals are most effective for generating a training response. But newer research has looked at short 30-second intervals. For instance, 3x13x30 seconds with a short 15-second recovery can produce even better outcomes, allowing higher intensity without a drop in oxygen consumption during recovery. Maintaining near-maximal oxygen consumption for as long as possible is crucial for developing maximal oxygen uptake,” Vesterinen explains.

This topic ties into discussions within Finnish skiing circles about the need for more speed. Ski Classics and cycling coach Mattias Reck emphasizes 40-second sprints with 20-second recoveries, often incorporated into high-intensity endurance sessions or long double-poling workouts.

“Shorter intervals are better suited for high intensities. Skiing as a sport can benefit from short intervals, preparing the body for sprints even when fatigued. This helps prevent excessive oxygen debt during breakaways,” says Vesterinen.

Traditionally in Finland, endurance training programs have focused on base training (low intensity), followed by steady endurance (moderate intensity), and then maximal endurance training. In Norway, a polarized approach is more common, with an emphasis on both low-intensity and very high-intensity sessions.

“Research supports that polarized training is slightly more productive. Short intervals may become more common in high-intensity workouts, as they allow even faster movements,” says Vesterinen.

The “Intervals vs. Tempo” debate will continue, and athletes should experiment to see which methods suit their training best and how their bodies respond to different intensity workouts.

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