What are you expecting? 5 minutes right at your FTP should be fairly easy to accomplish.
Has your FTP been correctly assessed?
That’s kinda the point. Twenty five minutes at threshold interspersed with 4 minutes of rest feel too easy to provide much of a stimulus.
Which is why I’m looking for the most appropriate adjustment to make from there.
I often hear, “it only takes 4 to 6 weeks to get results”, in reference to VO2 or anaerobic work, but no one ever says what to do afterward 
For someone who simply wants to get faster every year, I don’t think just 6 weeks of VO2 per year will cut it, so what exactly is the plan? In other words, how often should we return to VO2 and/or anaerobic in a given year? Do we cycle through something like the following?
- 6 weeks of Endurance/Sweet Spot/Threshold
- 6 weeks of VO2
- 6 weeks of Anaerobic
- rinse & repeat
Another way to ask the questions:
- How many weeks of VO2 per year should we do?
- How many weeks of anaerobic per year should we do?
Thanks!
/cc @trevor
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I know you addressed Trevor here, but I think you’ll want to use at least 110% for a 5 x 5-min workout. While I don’t think we need to do 5 x 5-min at the highest possible intensity we can handle, I do think pushing closer to that is helpful. I use the highest watts for which I can complete all 5 intervals at successfully and would be willing to do twice a week for a period of time.
The latter part is important, because it doesn’t really matter what you can physically accomplish for a 5 x 5-min if you’re not willing to repeat it enough times to get the adaptations. The mental toughness part can be trained as well though - you may surprise yourself!
Thanks. That’s definitely one way to go about it.
To me, a higher power 5 x 5 (at, say, 110% as you suggest) has a strong glycolytic component to the effort. I’m wondering if that has as much benefit to maximal aerobic capacity as, say, doing a higher volume (4x10, 3x12) closer to threshold intensity? Those efforts do not seem as if they would draw as heavily on the glycolytic system (though they do, also), but I don’t know if that makes a difference at all when it comes to developing aerobic power and capacity?
Since I’m training for longer distance events and repeatable power / power endurance more than for absolute top-end speed, I really want to make sure I maximize aerobic power and capacity, as opposed to having a bigger glycolytic battery.
I’ve read that a 1-min effort has an approximately even contribution from aerobic & anaerobic, and a 4-min effort has about 84% aerobic and 16% anaerobic (glycolytic).
There’s no avoiding glycolytic when trying to maximize your aerobic power, but I I think I know what you’re getting at - you’re not interested in a high VLAmax, and you don’t want to develop a massive “sugar burning” engine 
Many ways to accomplish this goal, and it may be somewhat individualistic, so as others have said, some experimentation is in order. My preferences are:
-
Accumulate a lot of Sweet Spot time (better bang for the buck vs. threshold IMO) - a couple sessions per week of 60-min of Sweet Spot
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For VO2, I like either something like Paul Laursen’s “T Max” intervals e.g. 2.5-min w/ 5-min rest (122%+), or the classic Ronnestad e.g. 3 x 13 x 30-sec/15-sec (or 3 x 10 x 40-sec/20-sec) (125%+)
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Others have good results with Seiler’s 4 x 8-min trying to average 90% max HR for the interval, so maybe ~ 106% to 108%.
I personally think the classic 5 x 5-min is overrated, except for maybe the mental toughness component!
Bottom line is intensity is a function of duration. For VO2, there’s no getting round the fact they hurt, and if you can do a little more intensity, you probably should (assuming you’re accumulating “enough” time).
Kristin Armstrong was on the podcast and implied that hitting at least 110% FTP was good, so accumulating more time at that intensity is probably a good thing.
That’s helpful and also lines up with what I am grappling with.
Here’s the issue. I have not been in a lab since 2019 and it seems like my HR to power numbers have shifted a bit compared to what they were then. Hard to tell.
What I do know, and what I do notice is that efforts around the 4 w/kg mark feel fairly easy and not painful. As long as I don’t go much above that, it doesn’t seem to matter whether the effort is 5, 6, 8 or even 12 minutes.
Two things that I have trouble understanding, however:
- 4.4 w/kg seems to be my “ceiling” for repeatable efforts at the 6-minute mark (i.e., with about 2 minutes of rest in between). If I’m careful not to go over that, I can repeat successfully, leaving me with a feeling of a “tough for doable workout”. I’m not thrashed in the least. Just “tired in a good way”.
If I go even a hair above that, however, I struggle to complete the workout. My ability basically falls off a cliff from there, and I go up in flames quickly the further I venture above that level.
- Yet, despite my describing efforts around the 4 w/kg mark (which I still think is a bit above my real-world FTP), I think I would struggle to hold this for a full hour, though I guess I would have to test that.
I’m sure that, to an expert, these elements would tell something about me and my physiology, but I’m not sure what to make of this and, from there, how to best structure my intensity workouts.
Do you have access to the video where Trevor explains the 5x5 intervals? The workout is done at a heart rate limit (1 bpm above lactate threshold). While you watch power, you also have to watch HR, to make sure you stay below the limit.
That sounds more like Trevor’s favorite threshold workout 5 x 5-min with 1-min rests, not the classic 5 x 5-min w/ 5-min rest VO2 workout, which you would definitely want to be above LTHR.
I should have been clearer from the start. I was initially referring to Trevor’s version of the 5X5s (i.e., with one minute rest).
The classic “all out” 5x5 are something I never do. These all-out efforts are just too hard on me and take me too long to recover from.
To be clear, 5x5x1 at threshold HR plus 1 is way easy for me.
Hi @CEBorduas, that’s a long thread! I hope you got some good insights. I’m about to jump into a meeting so my apologies I didn’t read all of it and I’m just repeating what was already said. But I definitely want to answer your original question.
I really don’t personally subscribe these by power. I give a general power range, but the focus is more on heart rate and feel. But you’re right that the power should be around 105% of FTP. Sometimes it’s a little higher and sometimes it’s a little lower. For example WKO has my FTP at 317 watts right now and the last time I did this workout, I was holding around 315 watts. The time before that I was holding around 325 watts.
The thing I want to address is your comment about the difficulty and I want to emphasize that these are not killer intervals and shouldn’t be. They’re hard, but you should have something left in the tank after doing them. For example, a few weeks ago I was doing them on Alpe de Zwift and completed a set I was very happy with at about 315 watts. I felt particular motivated that day so after taking a couple minutes easy, I climbed the remaining 20 minutes up the climb at about the same wattage. So, I definitely wasn’t “smoked” when I was done with the intervals.
We don’t have to be dead at the end of a set of intervals to get a training adaptation. In fact, I always like to remember back to an interview we did with Brent Bookwalter where he talked about looking at the week as a whole and being selective about going to failure. Here’s that interview:
A threshold workout for instance, one day it may be beneficial to go past that limit, go almost like a race, go as deep as I can, go as long as I can, go to failure and push a little through. At certain times there can be value to that physiologically and psychologically too.
More times than not, the majority of time, the voice of reason wins over. Once I’m not able to effectively or productively do whatever workout, or power number or heart rate number or whatever parameter we’re working with, then you cut it and you head back home and you factor that in and make sure to make good notes about it, and look at as many variables as you can and you adapt for future sessions.
I think there is some value to going past that and really pushing yourself to failure, past the point once in a while but that’s not something I’m doing on a weekly basis and definitely not during the season in between races.
Most of the days, no that isn’t the case, especially with where I’m at training now, it’s about laying down these really fine layers and getting the accumulated load over and over.
*If you go to total failure one day, it’s unlikely you’ll be able to come back the second, third or fourth day and do anything productive. *
So net productivity is actually enhanced by knowing that point where you should back off. Keep a little in the tank for the next day or two days from then or three days from then. Get back home and know that you can do it the next day.
You can always add on more, but once it’s done you can’t take it away. There’s no way you can undue an interval but you can always add more later in the ride or in the next ride or the next week.
That’s still one of my favorite interviews!
Hope that helps!
Trevor
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Hi @badkins, welcome to the forum! Just saw your post.
A full answer to your question is a very very long one, but here’s my best attempt at a short response. What you’re getting at is how to periodize your season and you’re actually thinking in the right direction.
It only takes six weeks to see the gains from VO2/anaerobic capacity work, but what’s equally important is that if you stay at it for too long, you’re either going to push yourself into overreach or lose so much quality with your intervals that they cease to have any benefits. So, it’s counterproductive to just keep doing them.
With a block periodization approach, you’d do either the VO2 or anaerobic capacity work for six weeks. Then you’d have 2-3 weeks where you’d back down on training and focus on performing at peak fitness.
After that, you’d go back to a few weeks of base training and then as you say, rinse and repeat.
Just remember that each time you cycle through that routine, you’ll achieve peak fitness faster. So, the next time around, you may only need 4 weeks of VO2/anaerobic capacity work to reach a peak. And the time after that, it may just take 2 weeks.
I still remember one of the best races of my life was Labor Day weekend during the 2007 season after I had gone through that cycle multiple times. I took two weeks almost completely in early August. Then I did a week of base work. Then a week and a half of anaerobic capacity work. Then I tapered for three days and had one of the strongest races of my life.
Hope that helps!
Trevor
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This has been a really great conversation! For anyone who’s interested in learning more about Block Periodization (a very complex subject just to warn you,) I’d recommend reading Dr Issurin’s 2010 paper explaining the basic concept: New horizons for the methodology and physiology of training periodization - PubMed
Thanks for the response @trevor - sounds like we’re going to have a future podcast episode to dig deep into block periodization!!
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Having read the thread, I picked up that the question was about Trevor’s classic 5x5s, hence the response I gave. The “interspersed with 4 minutes of rest” is what indicated it for me (4x1m rest):
That’s kinda the point. Twenty five minutes at threshold interspersed with 4 minutes of rest feel too easy to provide much of a stimulus.
Thanks to @badkins and @trevor , among others, for the thoughtful responses.
What I read from them is that even though I’m the opposite of looking for “being smoked” at the end of the workout, my concern with 5x5x1 at 105% being too easy to stimulate my top end aerobic system to adapt is probably not founded.
That’s good news. I’m certainly not looking to risk injury or burnout. I also don’t want to unknowingly train below what will actually stimulate adaptation. The workout is fun, but not enough for me to want to do it if it doesn’t improve my fitness.
At some point you’ve got to raise the ceiling.
I don’t think Trevor’s 5x5 HR-limited threshold workout for base is designed as a one size fits all, used all year around, workout.
You don’t have to do 5x5 VO2 max intervals. There are plenty of alternatives.
Absolutely, though the OP said he was working at 105% of FTP. FWIW, 5x5 minutes at 105% of FTP should also be relatively easy, when you consider that to establish FTP, most people take 95% of an output they can do for 20 minutes. Doing repeats of 5 min intervals at an intensity you can do for 20 minutes is very doable. Even 4x8s at that intensity should be very manageable.
IF you can’t do 5x5 or 4x8 at 105% of FTP, that’s a pretty reliable sign that perhaps one’s FTP is set too high.
That makes sense.
The question is: is there an intensity that is basically so low that the workout no longer provides any stimulus for supercompensation?
I no longer subscribe to the notion that a workout must absolutely “feel hard” to provide a training stimulus.
However, I do believe that there is such a thing as not hard enough to cause the system that was targeted to get stronger. It’s just not clear to me where that point is…
At its most basic, you need to consider Intensity x Duration.
With enough duration, essentially all purposeful “Exercise” can stimulate adaptation. The questions are whether they are worthwhile adaptations and the value of your time ;).