Use interval duration to guide what you train
Interval duration is the primary factor that determines the intensity of the effort and the type of physiology that will be trained. When you look at intervals that way, you’ll be able to target specific areas of your fitness. Here are general ranges of durations and the types of physiology they stress.
- 20-60 seconds: Anaerobic capacity
- 2-5 minutes: VO2 max
- 8-30 minutes: Lactate threshold
- 20-60 minutes: Tempo & sweet spot training
- 60+ minutes: Aerobic endurance, zone 2 training
If you’re new to cycling or interval training you should start with a higher number of shorter intervals to learn pacing. This allows you to get a feel for what you’re capable of and you can gradually build up your confidence and endurance from there. Over time, you’ll be able to extend your intervals and be more precise with your pacing to further improve your performance.
Learn when to add intervals and when to increase duration
For harder efforts, such as VO2 max intervals, you should keep interval duration constant and increase the number of efforts. For moderately fit cyclists, the amount of time-at-intensity within a single workout will max out at around 15-20 minutes. Only when you can complete these 15-20 minutes in the desired intensity zone should you start thinking about reducing the number of intervals and increasing the duration of each.
For lactate threshold and challenging aerobic intervals, the individual intervals are usually longer, 6-8 minutes each. Adding extra intervals would be too much of a jump in stress. It’s better to first add time to each interval to reach 10-12 minutes. Only after that can you add an extra interval while going back to 6-8 minutes of duration to make the jump easier to handle.
Increasing the number of intervals and their duration has to have a ceiling. The combined time-at-intensity during a single training session should stay in check for optimal results. Here are the maximum times-at-intensities for moderately fit cyclists:
- 3-5 minutes: Anaerobic Capacity
- 15-20 minutes: VO2 max
- 45-60 minutes: Lactate threshold
- 75-90 minutes: Tempo & sweet spot training
- 3+ hours: Aerobic endurance, zone 2 training
Understanding these limits will help you design your workouts to effectively target the desired physiological adaptations without risking excessive fatigue or injury.
Adjust the intervals to your fitness
Gaining perspective on the principles behind workout plans is essential, but understanding the relationship between intensities and durations alone is not enough to create an individualized plan. Always factor in your training history, phenotype, strengths and weaknesses, and the specific demands of event you’re training for.