In this RCA Podcast episode, Cam Nicholls is joined by RCA coach and science expert Ben Treble, who dials in from the middle of outback Australia to unpack a brutal but fascinating VO2 max session: high-intensity decreasing interval training.

This workout comes from a 2020 research paper and flips the classic VO2 script — starting with longer efforts and progressively shortening the work intervals while also reducing the "recovery" time. The goal?

👉 Spend more time above 90% VO2 max for better aerobic adaptations, without endlessly grinding through 4–5 minute repeats. Research paper here: https://pubmed.ncbi.nlm.nih.gov/32780251/

Cam shares his first-hand experience trying the session (including why the 2-minute rep hurt the most), and Ben breaks down:

• How the workout is structured and what intensities to target

• Why some athletes respond really well — and others… not so much

• Where this fits into a VO2 max "toolkit" alongside 30/15s and classic intervals

• How to think about specificity, timing in the season, and variety in your training

• Whether using ERG mode on the trainer is "cheating" (hint: it isn't)

If you'd like this workout built properly into your own training, check out the RCA 12-Week Custom Plan, where you work 1:1 with an RCA coach to tailor sessions to your goals, schedule, and current fitness.

Takeaways

A really important part of all training is variation. People do respond differently to different workouts. You can easily keep it interesting. I call it like a VO2 max toolkit. You've got the classic four or five minute intervals. You could use these decreasing working time intervals. Variation is key for effective training. Different workouts yield different responses. VO2 max workouts can be diverse and engaging. Incorporating variety enhances performance.

RCA 12 Week Plan: https://roadcyclingacademy.com/cycling-plan-custom/

Transcript:

Cam Nicholls (00:00.302) So welcome back to the RCA podcast where today I'm joined by one of the RCA coaches, Ben Treble, a science expert who's been with us many times before and is currently out on the road somewhere in the middle of Australia on some huge trip. Where are you Ben right now? It looks like you're in the middle of the country somewhere.

Yeah, thanks Cam. I'm currently in the Northern Territory on one of the bigger cattle stations called Newcastle Waters. I'm just here overnight at the moment and then we'll keep heading north this afternoon towards Catherine.

Yeah, nice. That room you're in looks like there might have been a few backpack backers murdered in that in the past. Looks nice and dodgy.

Yeah, I won't go into it, but we're going to go through a town called Laramma that has an ongoing murder investigation.

Oh, there you go. Yeah, it's a bit dodgy out that way, but it looks like you're having a good time watching your social media. So yeah, keep it up. Enjoy it. Today I wanted to talk about a science-based workout that's been going through the RCA coaching, you know, discussions recently. It was put up in our WhatsApp chat and we've created our own workout within Training Peaks that we've started to prescribe members to give a go. And I gave it a go myself this week.

Cam Nicholls (01:22.234) And I've sent you the paper. I actually haven't read the paper yet. So I'm hoping you can give us a bit of background on this science-backed workout that's, guess, relatively new and there's a bit more work that needs to be done in the space. But I'll give you my thoughts on the workout. But before I do that, can you tell us, you know, what is this workout and what exactly are we looking at in terms of, you know,

outcomes from a fitness adaptation perspective.

There was a paper by S. Lazar and Co. It was actually published in 2020. So I wouldn't say it's that new, but possibly the adoption of it is new. So they call it high intensity decreasing interval training, which is fancy word for doing high intensity intervals. And as you progress through the intervals in the workout, they're decreasing the work duration of each interval. So the quick example.

Say the first interval, you do it around three minutes. Then you have two minutes rest. Then you do a two minute interval, where that's the work duration. And then you have, say, around 80 seconds or 1 and 1.5 minutes rest. Then you do a one minute work interval, 40 seconds rest, 40 seconds down to 30 rest. And then it's 30 second work intervals until fatigue.

What range are we working at? we working at VO2 max? Are we working threshold? What are we doing?

Ben Treble (02:54.38) It's via to max. So the primary goal of this paper, and I guess this workout, it was to compare different interval workout types. So they had short, like classic fear to workouts. And then they had longer intervals, a reminder for the audience that anything above your threshold essentially just requires duration, but you can reach your fear to max at any intensity above threshold.

it just takes longer. So if you're say, if you're 105 % above threshold, you can still reach via two max, but it might take you 25 minutes to get there. Right. And so the crux of the paper and a lot of these via two max workouts around what's the best workout to improve via two max, that's really where they come from is how do we make these interval workouts more effective? And it's based on

That's a big assumption, but it's pretty validated that the more time you spend above 90 % VO2 max, the better the increase in VO2 max. So the better the adaptation outcome. And so they're trying to design and get creative around these interval workouts. What is the best interval workout structure that lets you spend more time above that 90 % VO2 max for less effort.

Okay. And looking at the paper and the participants and the results, was there anything worthy to note?

Yeah, yeah, it's keep in mind, it's a single paper is a pretty small sample size. So they had 12 cyclists, middle age, so around their 40s, they're moderately to well trained. So they had around a via two maxes of around 55 give or take. So that's just the population group of this study. So it's important to keep that in mind. And what they found was

Ben Treble (05:01.358) that you spent significantly more time in this high intensity decreasing interval type of workout compared to small or long intervals for VO2 max. What's important though, I think in this paper is that there's a high amount of standard deviation. So for example, one of the measurements was they spent around 312 seconds.

above that 90 % VO2 max, but your standard deviation was 207 seconds. So you had some responders in this sample group who might only have spent essentially what is an insignificant from a scientific standpoint, amount of time different to the other workout types. So some people had no more benefit that was measurable by doing this versus short intervals. But some people had very large

responses to it compared to the short and long intervals. And this is a trend in most of these, you you and I have talked about 3015 as a really good VO2 workout before from Ben Ronestadt. And even with within that, and he's done multiple papers on it, so then the research is a bit more conclusive, I would say that it's a very good recommendation. This paper is good. And I think it's a really nice indicator to say potentially, this has a lot of good potential.

But it's not a guarantee that it would work for you.

Okay, so going to the workout structure and how to do it because the thing I liked about it is I'd actually never done it before. I've done a lot of VO2 max training sessions, know, 30-15s, which we talked about, I started to incorporate that a fair bit after we sort of made some content on it. And, you know, I found that to be quite effective. I hadn't done a lot of

Cam Nicholls (07:00.622) 30, 15s in the past, so it was new. You get a bit of a dopamine kick out of it when you've been riding for a long period of time and it's a new workout to try. And you see a result as well, so that was good. In the past, I've done a lot of more sustained VO2 style sessions, like sustained three to four minute efforts, maybe if I'm out on the road, five minutes. But never this decreasing style session where

you you start off and this is what I want to validate with you because I think maybe what I've done was, you know, Ryan, our head coach dropped it in my training peaks and he said, look, this is where you start. Because obviously there's a starting point for these workouts and you can progress from there. But it sounds like what this paper is indicating is a little bit different to what I did, which was, I guess, dipping my toe in the water with this workout where I did a warmup. I then did some activation efforts.

I then got into the first set. and the first set was three minutes on, and this was, know, at, you know, VO two high VO two, two minutes, I wouldn't say recovery. It was probably, top end zone too. so for me, that was about my, was, try and operate just over 400 Watts for the three minutes. And then I came back down to two 50 ish.

for two minutes. And then I did two minutes back around 400 or just over 400. And then I came back to 80 seconds at 250-ish. And then I did a minute at around, you know, just over 400. And then I think it was 40 seconds maybe, or 45 seconds, I can't recall exactly, back at 250. And then I did the 30 seconds.

And then I went back down to 250 and then I did a recovery at like 150 Watts or something like that for seven minutes. And then I did a second set of that. But it sounds like in this paper, you continue on with the 30 seconds is what you said until you reach a fatigue state. Whereas I didn't do that. And I'm assuming, you know, the reason behind that is Ryan's like, well, you've never done this before.

Cam Nicholls (09:26.114) And I also indicated that I've been training for a triathlon and I hadn't done much VO2 work recently. So was a little bit, know, unconditioned for VO2. So he was aware of that. So what he's prescribed to me as a starting point sounds like it's not exactly what's put in the paper. Is that correct?

Yeah, you're on the money. It's probably important when we talk about the intensity in the paper, essentially they talk about the on and the off phase of the work and the rest components of those intervals. And they primarily did this using their VIA2max measurements, but they made some correlations to critical power, which they measured in the paper as well.

And so the relationship that they made was that the on phase was around 117 % of critical power and the off was around 83 % of critical power. So you're pretty spot on with what Ryan had you at. So, you know, that hundred and around the 115, 120 % of threshold was the hard. So like a via two max effort, it's pretty common. And then the off phase, a high zone too, I would say it's even maybe like

get reaching into zone three at 83 % of critical power for the off. So it's not an easy off. No, it's quite, it's quite key because when I first saw this and you sent it to me, my immediate thought was the recovery periods are way too long. Your heart rate will drop too much and the VO2 response will drop in those large rest periods too much. But then when I saw that the off phase was actually quite hard still at 83 % of threshold,

That's what helps keep the heart rate high and it's keeping that VO2 response high through the rest period. And then obviously, as you progress through those, you know, decreasing intervals, the work period and the rest period is decreasing at the same time. And when the work and rest is both decreasing, it's just maintaining that high VO2 max percentage towards the end of the workout. Exactly as you said, yeah, the goal is, and what they did in the study is that once you got to the 30 second

Ben Treble (11:41.824) interval mark, you had to repeat those until failure. So that's probably the key difference between what you did and what the paper did. But I think for our listeners, you know, you're still going to get a really good workout. If you just get to the first 30 second interval without continuing to failure, right? At the end of the day with all hit workouts,

time is, know, and availability is one of the challenges for all athletes. So if you only have an hour to train and that's what you can fit in, I think it's a really good idea to give it a crack.

So in the paper then, once they went to failure on the 30 seconds, did they then have a recovery period and do another set? Or is just one sequence?

Ben Treble (12:33.568) No, no. So they would do, for example, they would do this when they once they got to the decreased 30 seconds, there was 20 seconds rest. And then they would do another 30 seconds. And if they can't hold the power, that's when they would kill the session.

But what I'm saying is that, so once they got to that sort of failure point in those 30 second intervals, would they have a recovery period? Like I did, I had a seven minute recovery period and then I did another set. in the paper it sounds like that wasn't the case. Single set, it's interesting. So what Ryan has had prescribed me is, I guess iteration of the paper.

single sets.

Cam Nicholls (13:18.862) without the 30 second to failure and doing another set. And what he said he's done for a form of progression is at another set, like a third set. And he finds that that's actually really difficult. And for me, even though I haven't done a of VO2 max work, I'm relatively conditioned to interval training and I've done it for 15 years and VO2 max.

And I just found those two sets really actually quite a lot of hard work to do two of those sets, know, stopping at the 30 seconds and the the hardest repetition was actually the two minute repetition, not the three minute at the start or not the 30 second at the end, because I feel like that two minute recovery that you get after the three minutes at VO2 or just a bit over.

You know, at what did you say, 83 % of critical power. Yeah, which for me, 250 watts is borderline zone three in our seven zone, you power model. I did feel like I didn't get enough recovery. So when you start the, you know, the two minutes back at over 400 watts and you're not fully recovered, that two minutes goes for a very long time.

Yeah, it's a it's a pretty brutal session. I mean, I'm not surprised that the first one felt okay, especially if you've done a good warm up because your via to max is still going to be ramping up. And as it's ramping up, you're going to lean on and your respiratory rate hasn't fully increased yet. Right. So it's, you can even see it in the paper as you look at the the oxygen consumption line through this decreasing intervals that in the first one, it's increasing and it

it peaks at the end of that three minutes, right? And then you get the recovery. And when you start that two minute effort, you're already at like peak respiratory rate and your oxygen consumption is already very high. to me, that kind of makes a bit of sense that it feels pretty hard. All the first interval felt easier than the next one.

Cam Nicholls (15:28.91) in next one. Yeah, it was actually the second repetition in the second interval. So that two minute in the second set, that was by far the most challenging because I feel like, you know, one minutes, you you can get through one minute mentally pretty easily. 30 seconds you can get through, even though it's still hurting. But yeah, two minutes can be a long time on an indoor trainer at VO2 max when you're not fully recovered. So yeah, it was.

It was an interesting workout. I think it's, you know, going back to, you know, what you're saying about the paper is it didn't, you know, even though it's a small sample size and it's, you know, one paper, you know, it's, it's, you know, probably suggesting that it's not going to work for everyone, but it is going to work for, for certain people. And, you know, if you're doing VO2 max training and you're a bit

sick and tired of doing your standard go-to if you've done 30-15s for a long period of time or if you've done sustained efforts. From a variability perspective, there's probably a lot of value in it just in that. What would you say to that,

Yeah, I think there's a lot of value in it. You know, I had a couple key takeaways around when I read this one was that, you know, a really important part of all training is variation. And I think it's important even when we read papers, it's to remember, okay, people do respond differently to different workouts. But when we need variation, you know, you can do the 30-15s. And if you're doing a VO2 max block,

You can easily keep it interesting. You can have this, I call it like a VO2 max toolkit of different VO2 max workouts where you've got, for example, the 30-15s, you've got the classic four or five minute intervals. You could use these decreasing working time intervals. And you can use one that we've done before or talked about a little bit where you have like a classic, say, four or five minute interval where the first two minutes is.

Ben Treble (17:28.27) you know, around 130 % of threshold and then you go into the 120 % threshold. So you start hard and then finish not quite so hard. So I think it's nice in this sense. Like I saw it, I read about it. I think it has a lot of good potential. And based on the paper, like I will be adding it to my Fiat 2 Max toolkit. And I think everybody should consider giving it a crack. The other bit that I think is important to remember is

specificity in training. So, you know, and the timing of it. So depending on the time in the season, if it's just like a capacity block and you want to build via two maxes capacity, you could throw it into the mix along with some other workouts. But as you get more specific, if you're someone who does a road race that has lots of mixed intensities, I would say there's probably some benefits of doing this decreasing interval version because you're teaching the body to work at via two max at different

interval durations, right? Like two minutes, 30 seconds, two minutes, like different versions. Whereas if you're to do, something where you know you're going to do five minute efforts a lot or 10 minute efforts, then you probably want to grow yourself into those via 2Max efforts more than these.

Yep. No, good point. One, one final thing that I'll add from my experiences with the workout and I'm keen to get your perspectives as a coach. Uh, so the first set, I just struggled a little bit, uh, from a mental perspective. Like I was just couldn't get the power consistent. was kind of, I was a little bit above 400, but then I'll drop down to like 380 and 370 and then I'll get back to 420. And I was all over the place and I just,

I was losing a bit of concentration. think my motivation levels are a bit low as well after training for a triathlon, doing something that I didn't actually want to do. But, you know, what I did after that first set is I just locked it in erg mode. going, you know what? Like I'm not having a good time on the trainer, you know, managing this with my own, you know, my own mental capabilities right now. And I just...

Cam Nicholls (19:45.646) gave control of the trainer and said, you know, I'm just going to do the rest of the new, but I did the second set where it was just like bang on 400 Watts and then bang on 250 Watts and bang on 400 Watts bang on 250 Watts and I didn't have to worry about it. So is that kind of mid workout strategy based off of my headspace at the time? Like what do you say to that?

I think he did well to adapt to, you know, you had the self awareness to know, okay, this isn't going to work today, right? To do the workout off erg mode. And I think it's a exactly why we have erg mode in my view. I'm not anti erg mode. I think if you can do workouts without it, that's really good. The scientific side of me says I always like to do erg mode because then I know the workouts exactly the same. And when I compare week one to week two,

I can really look at acute heart rate response and know that it's a pretty good response. The only thing I would add to that was, yeah, I mean, it's a really good idea if you're struggling for motivation when you get on the bike, because it's pretty common, especially with an indoor session. And it's winter for our Europeans and North Americans. And I know a few of my athletes have gone through this in the last couple of weeks.

I find that music as well is a mood lifter. And for me, I remember when I had to do some really hard sessions on the trainer, like flicking it to erg mode and putting on those, whatever the tunes are that get you going. And then you just have to push the power. Like if that gets you through the session, I'm all for it.

Good. All right. I'm glad I didn't do the wrong thing because I'm going to be making a YouTube video about this workout and I can already see the people in the comments having a crack at me for, doing it in, in erg mode. But yeah, I certainly feel there's a time and a place for it. And, and to, be, to be brutally honest, like I I'm probably more of an erg mode fan when it comes to the trainer than anything else, because it's just, it's convenience of being able to just sort of switch off a little bit from that.

Cam Nicholls (21:48.59) concentrating and just letting the trainer do the work. I'm glad in this instance I get a coach's tick of approval. Thanks, Ben. I feel better about it now.

No worries, Cam.

Cool, well, if you're interested in learning more about this workout, we'll drop the research paper in the description. We don't currently have this workout in our off-the-shelf plans, but if you're keen to incorporate it and place it into an overall plan, check out the RCA's 12-week custom plan. You go to our website, go to the drop-down menu, you'll see the 12-week custom plan in there. You can work one-on-one with the coach. How that works is you have an upfront call.

with an RCA coach to get an understanding of who you are, what your logistics are, what your riding preferences are, what you're trying to achieve. And then after that call, the coach basically puts together a 12 week custom plan and they can incorporate this workout if you wanna give it a try. In Training Peaks, so it's all loaded in there and Training Peaks connects through to all the commonly used head units such as Wahoos, WIFT.

and of course training apps such as Training Peaks Virtual and Swift. So if you can give that a go, check out the RCA website. And Ben, thanks for your time. Good luck in the middle of Australia and we'll catch you in the next podcast.