@anthonylane great points. I think that many of these issues you are mentioning come from pedal stroke, I notice this in athletes who can do as you mention when working against resistance but not when having to generate it on flat ground.
The intervals are doable indoors on a roller or outside on a flat, but it would just be a different type of practice for you.
Hi everyone, sorry to be slow to pipe in here. Interesting discussion and debate. The conversation is quite long, so I’ll try to address everything I was tagged on, but I apologize if I missed something. Hope this gives some answers:
Execution
I do differ from Dr Seiler just slightly on these. In his studies, he had athletes do them as hard as they could while keeping the power consistent across all intervals. Since I use these in the base season, I focus more on keeping them around MLSS. Again, as you pointed out above, it’s not a specific number (i.e. going from 100% to 101% isn’t going to make a difference.) So, I give my athletes a few criteria:
Here’s an example of a session I did this winter to show you what I mean:
Notice the power is the same each session. Also notice that I don’t hit the upper limit on my heart rate (dotted red line) until the third and fourth intervals.
How Hard Should These Feel
This is a really important point that we’ve been trying to communicate on the show lately. The focus of our work should be on targeting energy systems. Using “I really suffered” as a gauge is often a bad gauge. To hit many of our energy systems effectively, intervals SHOULDN’T be as hard as possible.
In the case of these intervals, they should hurt and the final interval should be a bit of a struggle, but overall, you should get through them feeling like you could have gone harder. I found it interesting that you mentioned the workout is only about 60-70 TSS. Here’s my data for the workout above:
I did70 TSS not just for the intervals but the entire workout and I was very happy with that workout.
I’ll also mention that I did a combination of 5x5s and 4x8s from the start of December to mid-March this year. I was doing them twice per week and most of those workouts were in the 70-80 TSS range. My wattage for the intervals from early December to mid-March improved about 60 watts. So, I was quite happy with both the execution and the results.
Final note - I actually just recorded two videos this morning on how to execute both 5x5s and 4x8s. Those videos should be on the site in a week or two.
Finally caught up on this thread and I gotta say…you people are beautiful. This was super informative, totally nuanced, and I loved every word of it! 
Hello. Love the podcast and this is my first time on the forum.
A couple of basic questions:
Is a session 60min or 90min or 120min??
It is one thing to do 3 x 12min (@91-102% of FTP). Which I can manage easily enough… But its another thing to do 5x12.
Jay Vine (Zwift Academy winner) recently spoke about doing 4 x (4 x 5min @ V02max power) efforts… Which with 20min between each set would end up being a 4hours in the saddle.
What do we mean by “session”?
I would suggest that if your 4x8s at 100% FTP is hard, then your FTP is too high, perhaps way too high. If you’re defining FTP as 95% of a power you can do for 20 minutes, doing that reduced output for 8 minutes shouldn’t be hard at all, even repeated 4 times. Or, say you define your FTP based off an Hour effort, why would doing 8 minutes at a power you can sustain for an hour be hard?
I find that RPE for 4x8s is a great way to validate my FTP estimate, using the points above. I find that if I do 4x8s at ~105% of estimated FTP and they’re hard, but manageable, but at 110-115% they’re unbearable, then my estimate is probably pretty accurate.
@josemd, really sorry I never replied to your question back in July. My alerts weren’t working for a few weeks.
To answer your question… sort of. If you just compare a 2 hour base miles ride to a 2 hour tempo ride in isolation, you will get slightly more gains in the tempo ride. But the tempo ride also hits more energy systems and produces a lot more stress that you have to recover from.
But what’s important is how the ride fits into a weekly or longer plan. What’s important is the other work you’re doing. If you’re getting a couple days of high quality intensity work with the easy base miles rides in-between, then yes, the gains will be the same.
In fact, I’ll make the argument that the gains can be better because my experience is that when people go too hard on their easy days, their intensity days are lower quality.
@nettic good question.
The exact length of the session doesn’t matter that much, though I’ll share some thoughts on that in a minute.
What’s important is the time you spend “at intensity.” For work around threshold, Dr Seiler did address this in one of our episodes and I fully agree with him - you generally see amateur riders doing a total of 25-40 minutes at intensity total. Pros are higher but not much - in the 35 to 45 minute range.
My personal biggest workout is hill repeats where I’ll do 4-6 repeats of an eight minute climb at threshold intensity for a total of 48 minutes at intensity on the really big days (I only do the six repeat session a few times each year.)
When you get into harder work such as Tabata’s, time at intensity gets even smaller. For example, when I do Tabata’s I’ll do three sessions of 5-8 minutes. Depending on whether I’m doing 20-10s or 15-15s, that’s about 7.5 to 12 minutes TOTAL at intensity.
I know that sounds small and I’ve already seen feedback that some of our members feel that’s surprisingly small. But honestly, that’s what we’ve seen again and again in athlete’s training. The purpose of an interval session is not to destroy you. No one workout is going to produce an adaptation. So, the important thing is to look long term - how are you building your work over weeks. Each interval session is just a small part of that and should be manageable.
That’s also why I don’t personally get too concerned about TSS. If executed right, an interval session in the 60-80 TSS range can be very effective. One of the most powerful sessions I do to build a peak for key events is a sprint workout and it generates about 40 TSS. TSS is not the measure of an interval session.
In terms of how long the total ride should be when you’re doing interval work depends on the intensity. There is some evidence that work which targets anaerobic pathways and endurance work can cancel one another. So, very high intensity work such as sprints should be kept short. I tell my athletes no more than 1 hour door-to-door.
With very hard intervals such as anaerobic capacity and VO2max work, I generally have my athletes keep the rides shorter - under two hours. With threshold work, since it targets most aerobic pathways, the ride can be any length. I’d just do the threshold work while your legs are fresh.
Thanks for your reply. I read some of Joe Friel’s thoughts on the matter as well which made sense to me. Zone 3 riding is fine in the winter when you may have more limited time to ride due to weather, etc and during training camps. The other time of focusing on sustained Zone 3 (Tempo/sweet spot/race pace) is within 3 months of racing (my races are all in this zone from 3–7 hours). If I’m doing a block focusing on max aerobic power, glycolytic power, or sprint power, I would definitely go completely polarized where the easy days would be completely below aerobic threshold so I’m ready to hit it hard on the hard days!
Thanks for your reply
Trevor, what do you think about amounts much lower than 25 minutes? I ask because 25 minutes would probably crush me. I’m also 55 years old.
I’ve actually had really good gains this year. For my VO2max block I was able to get up to 3x5 minutes at around 115-120% of FTP. Attempting to do 4x5 or 5x5 with either result in the 4th or 5th interval at a much lower power/quality or me not being able to get off the couch the next day or both.
The other option would have been doing 5x5min at say 105% but then it would have been more of a threshold interval.
HI @AJS914 Thanks for the question! Yes, I think lower is fine. I often start athletes at 4x4 with 1 minute recoveries until they get the feel and can handle more. The key is to do the workouts with quality and if you’re trying to do 5x5s or 4x8s but fading in the later intervals, then doing less, but doing it well is a good option.
My suggestion though is to find that intensity that’s hard but manageable. Then as you get the feel for it, see if you can bump up to 4x5 and ultimately 5x5s. I’ve worked with guys in their 60s who started at the 4x4s and after a year or two were doing the 4x8s with no problem.
Trevor, as cross season approaches I find myself with less hours in the week to train so I’m looking for ways to become more efficient in my training.
I’ve been looking for ways to combine some workouts into a single ride and kill two birds with one stone. Example: I’m thinking about coupling a long endurance ride with some anaerobic capacity efforts aimed at building anaerobic capacity (not anaerobic repeatability).
So something like this:
2-3 hours of endurance, either starting or ending with a handful of one-minute anaerobic efforts with a 1:5 work to rest ratio. Am I best served by doing these anaerobic efforts early in the ride on fresher legs or later or not at all and keep the endurance ride focused on JUST endurance and save the anaerobic workout for another day in the week?
Pretty nice summary from Issurin’s paper on block periodization…I think it would be really cool to organize training around these residuals…hammer out Z2 work then schedule hard sessions targeting these systems in a way that doesn’t allow them to fall off.
Hi @anthonylane, it’s been a while since I’ve read the research on this, so what I’m about to tell you may be outdated. But, what I learned was that very high intensity work and high volume low intensity work tend to counter one another. Meaning if you combine HIIT or sprint work with 5 hours on the bike, the volume is going to undo a lot of the gains.
I still tell my athletes that the higher the intensity, the less time they want to spend on the bike. Sprint workouts I like to keep an hour or under. HIIT work, I generally like to see the ride no more than two hours. Threshold work, since it’s more aerobic in nature, can be combined with a long ride.
So, unfortunately my suggestion is keep them separate. That said, I also tell my athletes not to let the perfect get in the way of the good enough. I do think combining HIT work with a long ride isn’t as effective as keeping them separate, but if combining them is the only way to get both, then go with the good enough.
Hope that helps!
Thank you for the reply, I had a feeling trying to combine aerobic and anaerobic could possibly be detrimental. I suppose the one exception would be a race-specific application where you’re deliberately performing anaerobic efforts in a fatigued state. However, it seems like for building anaerobic capacity this wouldn’t be the best way to do it.
After reading @trevor’s reply and your follow-up @anthonylane, I would agree wholeheartedly. There are certainly applications where this may come I handy, but generally keeping them separate is a good practice. And for building anaerobic capacity, I would not rely on performing heavy anaerobic work within a large volume of aerobic work for improving your response. But perhaps getting you prepared for specific race applications, I can definitely see that.
You can direct us to a study in this concurrent setting you talked about?
Hi @anthonylane, have to agree as well! When the training is 100 percent focused on training adaptations, I would keep them separate. When you get into race specificity work, that’s where you sacrifice some of the system-specific adaptations for the race-specificitiy.
@susigan, unfortunately, that’s what I meant when I said that I read that research a while ago. I read it back when I was doing my Masters and that’s before I kept everything digitally. I can’t find those studies.
