I have the same question because the brief (30-45 second) intervals pass so quickly when the heart is still asleep. 
How many repeats are you doing in a set?
It was 2 sets of 6 repeats per set with 1 min recovery between repeats and 3 min recovery between the two sets.
During the 2nd set, I increased the recovery between repeats by 60 seconds.
I didn’t know about Billat intervals until now, but popped in because I’ve been wondering the same thing. What piqued my interest was a recent experience with two sets of 7 2:1 intervals, 1 minute on 30 seconds off, at 150% of ftp with several minutes rest in between. Very close coincidently to Billat and what surprised me about that was the experience of getting stronger as the workout wore on when my heart rate finally hit 90% of max 10 minutes in and stayed up there for the duration given the short cooldowns.
I’m concluding that the process of truly burning glucose isn’t in full swing until the metabolism, evidenced by heart rate, is fully engaged. And per Billat, the time spent in VO2 max is what counts.
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Any chance you could post your workout? I can certainly make one up … given the information you posted << …two sets of 7 2:1 intervals, 1 minute on 30 seconds off, at 150% of ftp with several minutes rest in between …>>.
Actually, it sounds pretty intense … like only to be attempted when fully rested…
Hi @Dave_C_Purdy. In a nutshell, On/Off work such as Ronnestad, Tabata, etc., the effort is too short to use HR a a gauge. Some have already noted, but for this work shoot for a maximal but even distribution of power across the number of intervals in a set. Best to think about each interval as a 9 of 10 on an RPE scale.
Just a consideration, this work is really taxing and requires proper recovery. The assumption here is that you’ve already done a lot of sub-threshold work to maximize your VO2 through long steady distance, tempo and SS, which we can do a lot of! Typically we might only do this type of work (Ronnestad, Tabata, etc.) to ‘sharpen’ ahead of your race or season. Although some do this work year round. If you are looking at VO2 estimates via wearables, it’s unlikely that you will see movement in that estimate due to the way VO2 is calculated, although it should be apparent in actual performance.
In regards to VO2 work, many will say “You have to do this VO2 workout to improve!”. Unfortunately, it doesn’t work that way. Always best to take a well rounded approach and include all variations of VO2 work from the On/Offs you’ve been doing all the up to the standard 4x4m or 5x5m. These in particular you CAN use HR, but only for post-analysis, meaning your HR should surpass your Threshold HR during the intervals (maybe not on the first interval). Hope this helps. Cheers!
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Honestly this wasn’t too hard on me, as in recovery was short. Maybe because the intervals and workout are both short or I don’t carry a large training load during a week. As @Kelly_Cline said, longer intervals are much more effective at raising and maintaining the heart rate. I definitely noticed my heart rate did not maintain and maxed at 95% of Max only towards the last three intervals, never reaching 100% of Max. I related this workout because it was recent and on my mind. I thought I noticed something but now think I only saw the effects of warming up.
My post came about because this is a subject of extreme interest to me. I only have a wattage meter on my indoor trainer and that is an iFit machine at that. I can’t rely on accurate wattage numbers. The best I can say is that they are consistent and I use them for reference, having correlated them against my heart rate over long rides.
I’m new to Intervals and just now coming across this thread. Reading through the thread has been great.
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When you say that the work “wasn’t too hard on me”, I assume you mean the short On/Off work? If so, you are probably more of a glycolytic rider and you probably have more fast twitch muscles. Some ‘high threshold time trialist’ athletes really struggle with this work. We are usually good at the short work or the long work but rarely both. But we should certainly train both the short and the long even if it’s a struggle.
In regards to your iFit machine, yeah, doesn’t matter what the actual numbers are as long as they are consistent. Cheers!
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This has been amazingly helpful. A lot of different interpretations or viewpoints have been offered, but in summation it seems to suggest that…
- RPE should ping VERY high, high enough that you cannot want to do it too often, but not high enough to dissuade one from doing it - only do these if you are really prepared, rested and committed…
- FTP target can tell the general direction to shoot, but the HR target tells you if you hit it or not
- a mix of VO2max work of varying on/off length and or block length is useful
- it is doubtful that one size/style could ever fit all riders
- 1 per week is likely sufficient, more than 2 would probably not allow time for recovery
Last season I worked on VO2max efforts of increasing block length (4,5,6,8,10 and finally 12 min blocks… ), and found the variety nice. Also tried to stay motivated by seeking out local strava segments whose peri-KOM times matched my block length focus. Lots of fun, lots to feel good about, w/ an occasional side dish of some humble pie here and there.
Whoever posted the podcasts, I’m going to start going through those over the few weeks as I drive to work.
Thanks!
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@Gerald , I finally got around to listening to that podcast; very good indeed.
A lot of good takeaways for me:
- zones are good for planning and communication, analysis, etc. Not so much as ends in themselves. Use zones for a mindful purpose rather than just using them.
- Zones (many) have discrete numerical definitions, but IRL an athlete might respond differently in those zones from day to day, or week to week. They can therefore be thought of more as a spectrum or continuum.
- it’s useful to forget about Zones occasionally and just ride experientially/by feel/RPE, but with a purpose, and learn/reinforce something from it.
- In one’s plan, be able to see both small-scale and larger-scale goals and structures.
- consider looking at one’s power curve profile, rather than just the FTP and 5m power, when coming up with a plan
- OTS sounds very common sense, I’m kind of wondering why that hasn’t been implemented more robustly already.
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OTS, for those that don’t know, is a FasCat tool on their app, which is Optimised Training Stress. The various inputs are already available on Intervals, in a way, to be able to get a “readiness to train” score/value. It’s requires a few manual steps, but I’m sure it could/would be automated in the next few years.
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Okay, I’ve finished my second week of my build block of training having finished the base portion.
I’m not yet “polarized” but my polarization index is increasing.
I’m defining VO2 max as the power that gets my HR into the desired zone.
I’m starting with 2 min intervals but the first 30 secs, I add extra intensity (50 watts) to get hr up faster.
I’ve been shooting for 90 % of max HR and I notice this is what Intervals shows as my thresh hold HR.
Is thresh hold HR the target HR for VO2 max intervals?
I race once a week and my peak HR in a race is closer to max HR than to thresh hold HR.
Does this mean I should increase the intensity of the VO2 max intervals?
Hello again, @Dave_C_Purdy. Here is a thread that I think you (and others?) will find invaluable. Let me know your thoughts. Cheers!
https://twitter.com/Paddy_Barrett/status/1755140012268523909
Late to the party so my point may have been made but a VO2max workout such as Ronnestad is, by definition, a heart rate based workout. I get my athletes to go over a power target (which is used as a guide) at the beginning of the intervals to get the heart rate up to or close to target. The HR will now stay in the prescribed zone thereafter.
On the other side of the same coin is Maximal Aerobic Power (MAP). This is power based. MAP and VO2max are interchangeable for practical purpose. In a MAP workout it’s the power target we aim for, disregarding the HR.
I so often see the term VO2max used where MAP should be used.
Speaking of coins, my 2¢ worth.
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Hi Bruce. Not sure what you mean by “by definition, (Ronnestad is) a heart rate based workout.”. Calling it a HR based workout makes it seem like reaching a specific HR is a goal/requirement. IMO and based on the Ronnestad papers, the goal of the workout is to achieve the highest average power across all three sets of intervals. HR is just a response, and as you probably know, highly individualized. Using myself as an example, when I do Ronnestad (or other on/off work), my HR barely averages my LTHR, especially on the first set. But my power is pretty consistent across all 3 sets.
VO2 max workouts are per definition judged on time above 90% HRmax. It’s the total time above a certain HR value that adresses the specific target for VO2max workouts. 90-95 % HRmax is considered the optimal target.
That’s why these are often done as 40/20, 30/30… That structure allows achieving more time above the minimal HR target.
After all VO2max is dependent on the maximum amount of O2 that can be delivered to te muscles. The 2 main ingredients are the amount of blood pumped through your body (higher HR = more blood pumped), and O2 delivered to the muscles (depending on mitochondrial density).
Perhaps read the transcript, or listen to the podcast. They speak to Dr Bent Ronnestad, who own studies are referenced.
It all comes back to what you want to get out of the session, and how that fits the demands of your event/ride.
I’m a fan of doing intervals that are more fun than others, as you’re more likely to complete them, eg. 5x5m are better for me, compared to 3x8x30/30. I’ll do both, but I really enjoy the 5-min efforts at the max average power possible. 5x5 can be demanding, and sometimes 6x4m is mentally easier.
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It depends on what you wanted to get out of it. I would seriously doubt that it is a failure.
Getting it to work for the individual seems to be key here. Individuals can have performance that varies from day to day.
I tried a VO2max 6x5min 115% 3min rest today and could not hold all the intervals at the full 115%… I did not feel guilty about 5-10% down-biasing the power 1 min into each interval as long as I kept my HR at 90% or above for as long as tolerable/possible. My intent was to base it on the HR interpretation (definition?) of VO2max workouts… Since I had done a TTT on Zwift a day and a half before this, my legs were quite tired and I felt that I could have done better had I been rested. So, I did not feel that I failed - I was able to keep my HR at 90% or above for just under 30 min, which was my goal. If I had been better rested, I’d have expected way more out of myself. Takeaway for me was that I need to adjust my plan to better allow for the TTT’s on Thursday nights. ;^)
An obfuscating factor in these discussions seems to be the multiple definitions (or interpretations, applications, emphases) of the term VO2max… The physiological definition of VO2max may be different from the definitions of “VO2max workout” and “VO2max zone”… and authors, researchers, coaches, fitness experts may have their own view of them. No one can claim exclusivity of knowledge and truth on this all (they are all just models, after all), so it’s gonna be a mixed bag, but there’s a lot of good stuff in that bag.
In the end, did the workout work for you? Do you feel good about it?
That’s where I’ve landed, and it feels like a constructive, balanced, sustainable viewpoint, for me. YMMV.
What software is this image from?