Mid-Interval: Turn Down vs. Shorten / Take a Break

Hey everyone,

I listen to the pod and spend a fair amount of time on here, but I’m struggling to find a clear answer. Feel free to link me to the correct thread and I’ll scrap this.

Occasionally, especially at the end of a workout, I’ll struggle to complete the last couple intervals. Is it better to turn down the intensity and finish the interval, or backpedal / take a break and shorten it? Does this answer vary for VO2/Anaerobic intervals versus Threshold / Tempo intervals?

If I were to guess, I’d say highest intensity VO2 and higher, it’s about time at the upper limits so cut short, don’t cut the intensity and then for longer sustain type of intervals, the opposite is true. Just a guess, but I’d like to get input from those more informed than me.

Thanks. :+1:

When I can’t finish either vo2 Max or anaerobic intervals, I just backpedal the last bit which let’s my heart rate drop a little longer between intervals. Not every day is a good day on the bike.

Yeah, pretty sure you are right. Point of V02 session is working at maximum aerobic uptake, or working anaerobic system if you are doing an anaerobic session if you turn down the intensity you are training the wrong thing i.e aerobic not anaerobic for example.

Whereas sweetspot is more about building a lot of time at this intensity to improve muscular endurance, so you will get more benefit by doing the full interval duration at a lower intensity, as you will still be working on the same energy system, just at a slightly lower intensity while still getting the prescribed duration which you derive most of the benefit from.

That is my understanding of it anyway.

1 Like

I would go in this order: backpedal —> turn down (just a couple percentage points) —> shorten/skip the interval


Yep, you got it, with a caveat. It’s this caveat that might cause some further discussion (this is the internet after all :smile: :wink:).

I’m sure you’ve run across threads where ppl struggle with VO2max intervals. In TR these intervals are based on a percentage of FTP. Whereas basing a threshold or sub-threshold interval off of % FTP is fine/reliable across riders, the same cannot be said for VO2max intervals. There is real variability there.

Soooo…if in the past you have been able to complete a workout (for example) of a set of VO2max intervals set at 120% then you should not be bumping that down too much to get through (2-4% might be fine). You’re having an off day, so better to cut short, backpedal, etc.

On the other hand, I regularly set my 120% VO2max intervals at 114-115%—even on a “fresh” day. 120% is just too high. I don’t do this because I struggle and then turn down. I do this because I’m trying to maximize time in the zone. (ideally getting to 15-20mins total), and 120% FTP simply isn’t right.

@chad and @Nate_Pearson have indicated several time they are in the middle of working on something to address this. I’m excited to see what they come up with.

In other news, the variability above threshold is what iLevels in WKO4 is designed to address.


Proper post @tshortt. Not everyone can, or needs to hold the 120% of FTP for VO2 Max intervals. That zone runs from top of Threshold around 105%, so there is plenty of that range to work with, depending on interval length.

I made a chart that shows what happens when you use the Workout Intensity adjustment to alter a workout set at 120% of FTP (top of VO2 Max).

Again, depending on interval length, a person might be able to drop to 90% Intensity and still be working the VO2 Max system.

That 120% is a starting point, but not necessarily correct or possible for everyone. So it is worth experimenting to find what each person can handle to maximize time in zone, without bailing early.


Dang it I forgot to post that chart. Really useful

1 Like

Ha, I’m happy you nailed the content :smiley:

I’m a little unclear as to what this is referring to. I’ve seen the WKO4 referred to before in other threads as well.

Thanks for the input everyone, especially the very thorough answer tshortt

Chad, do you apply this to mixed workouts with vo2max components? Let’s say you’ve determined you need to do 120% intervals at 116% FTP, what would you do with something like Mitchell or Richardson +3? Would you start the whole workout at 97% workout intensity? Or would you perform the threshold/sweetspot “recoveries” at 100% and only the bursts at a higher intensity?

1 Like

As tight as some of those bursts are, changing intensity between the hi/lo seems like it would be tough. Assuming that the default 100% is not possible or practical, I would likely just try to find an adjustment that keep my respiration rate quite high and still allowed full completion of the sets.

I struggle with this sometimes as I want to do them at 100%, and often suffer too much too soon. And that leads to more issues later in the workout. I almost prefer starting a bit conservatively (based on prior experience) and then turn back up if I feel I can handle more through the middle sets.


I’m glad you said that. I’m the absolute same and I have a history of waiting too long to make adjustments and by that point I’m cooked. Starting above-threshold workouts a little conservatively and then readjust is part of my process goals for the next training block!


WKO4 is a training analytics software package from TrainingPeaks. (https://www.trainingpeaks.com/wko4/)

Many folks on the forum use it and are quite proficient. Alternatively, Golden Cheetah is another piece of training software that provides similar functionality.

They provide metrics related to your training that are well above and beyond FTP. The additional functionality comes at a cost (literal and in terms of your time). Without getting too controversial, I think it’s safe to say that the vast majority of TR users do not need these tools. Your coach might, but…anyway :smile:

Often, in order to make sure everybody on a particular thread is “speaking the same language”, so to speak, someone will say something to the effect: “it’s like such and such in WKO4” or “whatchamahooch in Golden Cheetah”. If you can get past users passionately debating which is better and who has all the valid metrics :slight_smile: you can learn a bit of physiology and training practices.

Addendum: just to be clear about why I included that iLevels comment. What I was driving at is that this “variability of response at intensities above threshold…vo2, etc.” is NOT a TrainerRoad specific thing. It’s legit. It’s possible you’re on a bad day, as others have suggested. But it’s also possible that you’re experiencing this fairly common phenomenon.

I don’t understand the logic here. Backpedaling shortens the interval length, which you have listed as the last option.

Backpedaling is typically something you’d do for 15-20 seconds and your HR would still stay pretty close to the intended level. I also think that most people have the auto-pause feature enabled so you should still get your money’s worth out of the interval.