Boosting performance with sub-threshold intervals

So what is the best interval session for a road cyclist? The fact is that there is no single interval session that will cover all your needs for high-intensity training. On the other hand, though, some intervals should be an integral part of your training regime – at least if you ask me.

Interval training with high intensity

Sub-threshold intervals should be an integral part of any training plan to build aerobic endurance. When you train at an intensity slightly lower than threshold power, you can work for a longer time with minimal anaerobic metabolism.

Because these intervals are performed at an intensity safely below threshold power, you can perform impressive amounts of these without overshooting. So sub-threshold intervals improve your aerobic performance and have almost no impact on your anaerobic endurance.

Usually, you would use durations of sub-threshold from 10 minutes and up to 45 minutes. However, triathletes competing in long-distance events (e.g., iron man distance) might choose even longer intervals.

VO2 max intervals and threshold power intervals are the two most time-effective ways to increase performance.

But there is one major problem: high-intensity intervals only work when you finish them.

If you do not maintain the correct intensity throughout the interval session, the effectiveness decreases. Thus, you will achieve better training if you choose a power with a higher success rate.

My experience is that the success rate of high-intensity intervals is lower than sub-maximum intensity intervals. Still, sub-threshold power intervals do offer significant improvements when made in appropriate doses.

Also, there is an argument that there is a physiological sweet spot because you can train at quite a high oxygen consumption without going anaerobic.

Thus, you will give a great lift to your aerobic system (and almost nothing to your anaerobic performance). And that’s why sub-threshold intervals are an integral part of my training programs: they work so well.

Here are three examples of workouts where you use sub-threshold intervals to boost your aerobic performance:

Sub-threshold workout #1

10 min warm-up
3 x (10+5min) sub-threshold / recovery intensity
5 min cooldown

Sub-threshold workout #2

10 min warm-up
10 min sub-threshold intensity
20 min endurance
10 min sub-threshold intensity
5 min endurance
5 min cooldown

Sub-threshold workout #3

10 min warm-up
5 x (5+4min) sub-threshold / endurance
5 min cooldown

If you want to integrate sub-threshold intervals in a structured training program, a perfect solution is waiting for you here: 12-Week Winter Training Program.