VO2max intervals: FTP% target or HR target?

Training
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TL;DR: Am I going hard enough on my Seiler and Rønnestad? Also ERG mode or something else?

Greetings… I am working VO2max intervals into my weekly plan. Should I be focusing on simply the FTP% or the MaxHR% as my target to determine “am I going hard enough to reap benefits?”

When doing the Rønnestad 30-15 at 125%, my HR is just barely coming up to 140bpm. [ 140/167 ≈ 84% of MaxHR], and the average HR over the last 30/15 is 132bpm [79% of MaxHR].

Also, should I be staying in ERG mode for the structured workouts? Or switching to resistance/slope/someother?

Any kind and constructive pointers, clarifications and thoughts will be appreciated.

Thanks, Dave

Background: I’m a 60 y.o. cyclist, recreational, but always interested in increasing my fitness and efficiency, and I ride with a group of mid-20-to-60+ somethings that are quite fit, and I (usually can) keep up. Per intervals.icu, my FTP is around 245, VO2max around 51; empirically, my MaxHR is around 167, early AM resting HR is low 40s. My W’ is estimated at around 18kJ.

Years back I would do a century per week, and about 200mi/wk. Recently I’ve switched to more intense rides of 30 miles on average, still around 200mi/wk.

I’ve done (I think) my homework on looking at Seiler, Rønnestad, Billat and what their studies showed. I used Xert for two years and have a basic understanding of the models…

My -understanding- of Rønnestad’s protocol is that it is a way to achieve VO2max load on your system yet make it more repeatable, in the same sense that Sweet Spot/OU work allows you to accumulate load comparable (not =) to FTP-level-strain, yet keep it more repeatable.

I’ve done my base work and SS training so far this spring, and have started moving into the VO2max portion.

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I assume 30-15 is 30s on with 15rec? Your HR won’t rise like it would doing 5 minutes at 115% so I wouldn’t worry about that

As for ERG mode. I’m probably in the minority here but I don’t like it. If doesn’t help develop a smooth efficient pedal stroke. Yes, you hit the exact numbers etc etc but pedal stroke can suffer if you’re really on the limit

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Thanks. I will just try to trust the science, maybe shorten the rest-between-interval down to 3 min or so, and also try it in “incline” mode.

My impression of “erg mode” is that it does force one to trust the system, and at the same time removes some control from the user. I actually like the idea of having to do the gear management/shifting/spin-up in order to reach the target wattage. It just seems more real-world to me. I guess the upside of “erg mode” is that it removes a variable from the mix - human error, though.

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No ERG for hard intervals, %FTP
If you came from a SST block, recheck your ftp, 20m test or so.
Vo2max is very taxing, so not sure how many times a week you plan to do them but definitely being well rested can help with your HR (it can rise faster when rested). Most of the time vo2max intervals (when in block) are performed with lowering weekly load.

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I am still in the process of building my own philosophy around training and intervals.

My current thinking for VO2max interval work is to perform a maximum effort for the interval knowing that you have to repeat it X times. The goal is to complete all the intervals with a consistent power number. To do this I would switch to slope mode and adjust gearing when the interval starts.

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I am very similar to you, 62, 220 FTP, 50 VO2max, max HR 171, resting HR 50, do less miles per week but about same time as ride off road about 25% of time.

I hate riding indoors so all my training is done outside, so no ERG mode. Usually have good weather and flat, uninterrupted cycle path to train.

I regularly do 40-20, 3 sets of 10 at target of 125% my FTP (so same time in zones as your Rønnestad 30-15) with 5 minutes between sets. I say target of 125% as I meet or exceed the target every interval, closer to 130%, until late in the 3rd set and then I am struggling to hit the target and occasionally fail. My HR for the final few intervals is around 160.

So based on my experience, I am wondering about your settings/protocol. ie your FTP, is ERG mode really 125% of your FTP, are you doing 30 seconds on, 15 off, is there 5 minutes between sets, etc. A my understanding of 30-15, 40-20 or similar Tabatha intervals, is empty your anaerobic system, work you VO2max, recover but not enough to completely recharge your anaerobic system, repeat and then repeat again and the 3rd set should be really challenging (if not do a 4th), working both your VO2max (end of sets) + anaerobic (with constant accelerations).

Most riders compliment their Tabata intervals with regular VO2max intervals (on other days) for me that is 5x3, 3x5 (not so much), 2x8.

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@Nick_Cowie, I tolerate riding indoors because of weather (upper Midwest US), roads and the difficulty of finding suitable lengths of safe pavement to do intervals w/o interruption (Madison, WI) … When weather, job and other things permit, I ride and (mostly) keep up with some

One thing that I noticed is that my W’ seems much higher this year - I did an overload of basework because I was recovering from Covid lungs, and lungs have finally started to clear up.

I am going try to repeat the Rønnestad-esque intervals tomorrow at a higher intensity and shorter rest between, and use that to ‘titrate’ my response to the load - and find the mixes of FTP%, duration and rest-between to keep my HR in the 90%-95% region (per Jan Helgerud & Kjetill Høydal, and many others) consistently.

@James_Clarke @Lukasz_Pludowski , & @nasatt thanks I will try the slope mode some more and see if I can fine tune my interaction w/ the gearing & tweaking the slope/incline value - and maintain compliance with the interval’s expectation.

I finally realized what part of the confusion in the discussion regarding “VO2max” is caused by : we can mean many different things

  • the specific zone Z5 in terms of FTP (106% - 120%)
  • any workout that (purportedly) helps an athlete raise their VO2max [ Seiler-type blocks, Microburst workouts in the 120%-130% range, Hard-Start Intervals (starting in the 120%-130% range and then tapering down just enough to keep HR high but enable completion) and a slough of others.
  • a heart rate range that is associated with being favorable to increasing one’s VO2max (think “Borg Scale”, RPE, Ventilatory Response, etc.)

The common thread to me, though, is that a VO2max workout should have an intensity to it that challenges the performer to finish it in terms of breathing… I’ve seen differing degrees of freedom regarding ERG vs. other modes, but still the deciding factor to me seems to be keeping the ventilatory response very elevated. A lot of threads simply said, in one way or another, that we all respond differently to training, so there is no one-size-fits-all plan or interpretation. But the athlete has to do the work, period.

Thanks @ all for your comments, pointers and thoughts.

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Hi Dave,
just like you I’ve read all that stuff you mentioned. There’s a lot to learn how doing the right thing and then doing it right when it comes to working effectively on the bike. I’m 74y and keep doing these kind of intervals once a week.
My experience: Those 30/15s are great. But don’t trust the numbers too much. Listen to your body - and your heart is a part of it. As you mentioned Roennestad wants us to get north of 90 pct HRmax. So shoot for that goal. And as the slow component of VO2 causes this inevitable HR ramp I do the Billat style. Start very hard to get HR into the target zone ASAP then cut back to hard but sustainable. And as HR is creeping up you should accordingly decrease power. The main goal is to accumulate as much time in zone as possible. Not power zone but HR zone. As long as you’re beyond 90 pct HRmax you’re in the target zone, no matter what power you crank out. Most guys get this wrong and quit doing the work when power tanks below a certain level.
Indoors I use erg mode. So I don’t have to gaze at the numbers, no shifting, just being focused to do the hard work. And it’s a great relief to play with cadence when switching between work/rest without struggling to adjust power. The trainer keeps you going right.
It make take some attempts to adjust your intervals but after that it gives you a reproducible level so you can monitor your improvement.
When riding 30/15s on the road I look for a suitable climb as it’s easier to cling to the desired power numbers uphill.
Once you got it right don’t increase power but increase the number of reps/interval.
Hope that helps.
Gerhard

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Hi guys,
addendum to my input above. Connecting VO2max to power numbers is a misconception. Power means output as a result of your input which is metabolic energy conversion in the working muscle. To elicit beneficial adaption of the mitochondrial capacity we have to go close to HRmax (>90 pct) and to stay there as long as possible. As we work in the severe zone, metabolic byproducts compromising efficiency are constantly accumulating and force as to cut back or stop sooner or later.
So only look after HR and forget power or any percentage of FTP or power zone. As efficiency goes down with time we must reduce power output to avoid rising of HR up to 100 pct. This is the Billat-method. When you calculate NP of a 14x30/15 interval set it´s lower than going at constant power for the same time but that´s totally ok.
Once more: Goal is not to put out as much power as possible but to stay above 90 pct HRmax as long as possible. And the 30/15 concept by using decreasing work-interval power is very effective. 4 to 5 min rest between sets are ok, shoot for 3 sets.
As the VO2max system needs 60 to 90 sec to ramp up it will not be smart to finish the interval after 4min as most guys do.
Another way to do this VO2max work are 8min intervals - but again: Not constant power but constant HR instead. So shape the power demand by giving it a sligthly inclined profile. And again: Start hard to get into the desired HR zone ASAP.
Last note: Doing too much work above FTP will inevitably compromise your FTP. That sounds crazy but it´s a fact. All the pros do know this and you will find them riding in Z2 most of the time (the Stephen Seiler polarised approach). I was doing TH work for years and I got a good punch from that early in the year. But I quickly plateaued and wasn´t able to climb hard for an hour on consecutive days when I went into the Alpine climbs in summer.

Ride smart, and sometimes very hard!
Gerhard

3 Likes
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Thanks, I get it now and I’m making progress.

I’m using both Seiler blocks and Ronnestad intervals. Still ‘titrating’ to find the right levels but getting better at reaching the 90% area and then hanging there. Sometimes I get the expected “panic” or “impending doom “ feeling, partly because of my exercise-induced bronchostriction, but I know the intervals are finite and countable, ie. I know each one is a small attainable goal.

I can affirm that I can only do these sessions well when I’m not tired. It requires both mental and physical effort.

I can also see results, as my FTP is slowly increasing, and I’m also attacking my power curve at the time intervals where it looks like I could improve.

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Hi. I very recently went through the same doubt, after hearing a podcast episode by Empirical Cycling. I used to do classic 4x4 etc, and felt lactate and pain. But HR did not climb up that much. In the podcast, they (in my opinion, correctly) pointed out that Vo2Max is about the heart, so better to focus on HR rather power. Like for Zone 2. And, I think, unlike FTP (I target power, there, as a proxy of lactate. HR drifts up until the end of the session).

I think training Vo2Max by HR is espcially relevant if the goal is health rather than bike racing.

As a consequence, I started doing 30/15 at a given power (at least 125% of FTP). They were hard and at the end of the third set HR was way above 95% max. Lots of pain, and not too many minutes around 95% of HR max: it was a linear ramp up from 85% to 99% :hot_face:

I recently switched to what I heard is nicknamed “rattlesnake” 30/15, where each set is “warmed up” by a 60/90s strong interval (there is a specific protocol, but I just do a very hard repeat) in order to push HR up. During the rest of the set, I start with high(er) power to move HR further up to the level I target (I want 93-96% of max) and then adjust, i.e. cut down power to stay in the target HR range. I think this is what Gerhard, above, suggested too.

This protocol is allowing me to have a whole lot of minutes at around 95% max HR without pushing all the way closer to 100% and suffer the pain that getting above 95% generates. I cannot say if this is working better than other protocols, but I feel fit and I “like” it.

Give it a try!

Cheers.

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Vo2max works on your hr pump capacity not mitochondria, for mitochondria you ride z2.

I kind of don’t understand training a lot of vo2max as a healthy goal. A lot of fatigue, effects dimishes like in a weeks, not pleasant at all if done correctly. For me much better would be to just to get on a faster ride with a local group where people are pushing hard and a ride is constanlty on/off. You got a nice ride, good motivation and a lot of hr above z4.

Probably best would be to use hr and power at the same time. At least for me vo2max done by power results with data where I can compare my hr to my power. And if you are trained, follow a training plan etc, power is much more stable and much easier to train by even at vo2max than hr which can be skewd by tiredness, hydration, food, outside temperature, coffee, and millino other things.

The reason to train vo2max by power at least for me is a nice way to see and controll if I’m up to a task. Depends on my hr beahvior vs my power I see if I should continue or it just makes no sense and it would be better to rest. When doing vo2max by hr there is a very high possibilty to push your hr even if it doesn’t want to get so high being tired etc.

Nothing wrong with training by hr but it should involve very good control of your rpe and overal training load. Without power you jsut lose a very nice way of seeing you are tired which can result with overtraining. At lest ofr me it would be really hard to decide if my hr is slow to respond bc I’m tired or bc I. ride to easy. And it happens a lot where after couple of kms i see my hr very slow to respond and I must be tired or I see just the opossit, my hr jumps like in seconds and immidiately lowers and i know this day will be a good day etc.

1 Like
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You reduce the volume, and increase intensity.
VO2 workouts are usually done in the build phase (some call it speciality).
In the traditional periodised training plan, this would result in the highest weekly load compared to the base phase.

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I was following Tim Cusick on this. He clearly lowers the weekly TSS for Build phase comparing to base. It make sense for me. Can you give an example of >968tss build week with two days of vo2max? I just can’t see a possibiltiy to be fresh to do those intervals and still rising weekly tss unless other days are around 300 tss which makes vo2max days impossible to poerform.

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Based on your weekly hours and TSS, here’s how my training plan would show. I’m guessing your annual hours (+/- 525) and load (+/- 35k), give or take 10%.

image
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Your goal event looks to be in week 28, mine is week 27.
I have 3 base blocks, where you have 4, so my base 1 would be your base 2.
My prep and testing is done in the 1st 3 weeks before my Base 1.

From there onwards, the comparison is almost the same hours/load in base, which is how I was able to match up your plan and my plan.

While there is a maintenance period of CTL/fitness for both, i.e. the same load across both periods of build, your Load is reduced, whereas mine increases. This is where I refer to having a peak load in the Build phase. Your overload is in 2 weeks, whereas I’m overloading more gradually over the build period.

You asked about 2x VO2 sessions in a 18 hour week, or a 968 load week. I don’t go that high (load and hours), so it’s easier to plan 2 hard sessions and still maintain fitness. My hours in the Overreach/Peak period of 2 weeks will have lots of race like efforts (high intensity) requiring more rest (hence the lower load).

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Thank you for very comprehensive answer. That graph I posted was taken from Tim Cusick pdf. I scheduled my plan on it’s base but with lower overall weekly tss by 10-15%. Your answer is very dense with details so I need some time to read and understand it fully, but I’m really thankful for your answer.

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A podcast that’s worth listening to, with some really good advice is this one:

16:44
What works for one doesn’t for another.

What I would do might be different too, say Tim. However, as he is WKO Product Leader, he has had a fair amount of influence in my development over time.

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The option for using your Powercurve in programs was recently added. Instead of using 125% FTP, you could use 100% of your 5 minute power, which for many/most, correlates nicely with VO2Max Power.

So a single set of Ronnestads could be

13x
-30s Go Hard 240s 100% MMP 240s power=3s
-15s Recover 55% MMP 240s power=3s

It is 100% of VO2Max for 30 secs, then rest at 55% VO2 Max, and repeat.

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There are not only billats and 4x4s. Billats make you spend little time on vo2max, many program them at 100% of p5 (I think this is a mistake). You have more options like the Bossi, Lisboa ones that are a bit different, you also have the option to do micro breaks, start hard and lower intensity. There are many options. The watts are taken as a guide, but what really counts is to be above 90% of the fcmax.

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I’ve recently finished my Base period and have introduced some VO2 max sessions (1 per week).
I did a 30/60 that was kind of strange.
The 30 sec “work” targets were 182% of FTP.
This seems excessively high but since the intervals were only 30 secs, I decided to try it.
I did have to extend the last few rest periods but kept the power targets the same.
My question concerns time in HR zone.
When looking at my HR, it seemed like my HR was slow to rise during the work interval , taking 15 sec or more, and about 1/2 of the time in "HR zone "was during the rest period.

Does elevated HR in the “rest period” still count?