Boosting performance with sub-threshold intervals

Richie Porte at World Championships 2011

So what is the best interval session for a road cyclist? Fact is that there is no single interval session that will cover all your needs for high intensity training.

Though, there are some intervals that 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 with the aim to build aerobic endurance. When you train at an intensity slightly lower than threshold power you are able to work for 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.

Normally you would use durations of sub-threshold from 10 minutes and up to 45 minutes. 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 manage to maintain the correct intensity throughout the interval session, the effectiveness decreases.

Thus, you will achieve better training if you choose an intensity with a higher success rate.

It is my experience 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 cool down

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 cool down

Sub-threshold workout #3

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

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

10 comments… add one
  • thomas Link

    thnx for sharing this !

  • Marcus Link

    any thoughts on combining sub threshold intervals with threshold work, so for a 10 minute interval maybe do 3-4 spikes (30-60 secs) at threshold or threshold+? thanks!

  • Andy Link

    Hey Jesper, why are your suggested sub-threshold intervals so short? Are you sure the prescribed 30min, 20min or the 25min workouts will achieve aerobic endurance? Wouldn’t it be better to do these lower intensity intervals in one block rather than breaking them into segments?

  • @Andy – Since it is a sub-threshold interval, it is also be possible to do one long 45-minute interval to get the interval training done. Actually, it would probably provide a great training boost – probably even better. These 3 examples were from a series of short training sessions. I agree that these are in the easy end of the sub-threshold sessions I normally use, e.g. in the 12-week winter training program, where I use sessions including a total up to 60 minutes at sub-threshold intensity.

    @Marcus – Yes, it will add an extra boost to your performance as long as you finish your planned intervals.

  • Nikolaj Link

    So when you say sub-threshold, how much of your lactate threshold Heart rate is that?

  • Brandon Link

    Please help… I am lost with the Sub-Threshold vs Super Threshold terminology. I seem to find plenty of information that reference the two but I can’t seem to find much that explains either in depth. Could someone break it down for me? I am currently registered to do my first Ironman and I want to do well, but I’ve never gone this distance. I have plenty of experience in ultra-intensity interval workouts and they’ve served me well, but I want to help move my body to a more efficient fat burning state. Thanks in advance.

  • @Brandon – You can find explanation of training intensity here:

  • Jim Link

    It seems intuitive that uncompleted threshold level intervals won’t give you the same benefit as completed intervals. But how is this any different than uncompleted sub-threshold intervals?Why is this a reason to simply rule threshold intervals out?

  • Jim Link

    One of the benefits that you stay about sub threshold intervals is that they don’t impact anaerobic endurance. Why is this a benefit ?

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