@trevor thanks for suffering for us 
My question about this is that the heat map for your “Good Test” is “cleaner” looking like you stayed pretty consistent - constant yellow and not spikes of yellow, orange, and red. The bad one looks to be all over the place. Is there a reason that doesn’t have to do with the workout on why it looks cleaner or is it that when you are “ready” you tend to produce workouts that look cleaner?
@ryan I like the visual. Is that something I have not discovered in WKO (so much there, even by default, can miss some that are right in front of you) or do you use something different. I like the ability to annotate each interval with numbers and seeing the visual as well.
Nice job with the test and making Trevor suffer 
@bgkeen, thanks for the question. There’s two reasons for the difference. One is definitely the fact that I was struggling in the workout with Ryan and having a hard time maintaining my power. The other, and probably the bigger reason, is that I had my trainer in erg mode for the 4x8s. I do agree with Ryan that there’s a lot of value in self-pacing and I try to do that regularly, but sometimes I like to just get on the trainer, find the right wattage for the day and let the trainer run the show.
@bgkeen thanks! I always enjoy the days I can make Trevor suffer a bit, because they are so few and far between!
So that view is actually an app that I was introduced to recently and have been enjoying alongside WKO5 and Xert. This is intervals.icu and connects with your social accounts (Strava, etc.) to pull in workouts. They’ve been doing a great job developing it!
Ryan
Thanks! One more tool for me to play with data…I’m sure my wife will appreciate 
@trevor that explains it. It would be impressive in your “feel” to be so precise. I think the use of ERG mode would be a good topic - when to use or when do you prefer to use. I know for me, I will use if I am truly going easy and just want to focus on being on the bike with a low HR and practice other things like breathing. I when I do my 1-2 hours <50% of 5 min max, my HR can be 10-20 bpm lower than being in slope mode or more if just riding with the terrain changes of zwift.
Here is my 4x3 min from today (I adjusted the plan because I bruised my knee chasing my kid and it was bugging me on Wed AM).
My target HR was 175 bpm which is 95% of my max. I modulated my power by feel but had 280 watts in mind (110% FTP). On the first interval I went out close to 280 but felt like it was too hard. Ended up with the following average powers: 266, 259, 258, 261.
While my peak HR was quite a bit higher than my target (178-179 each time) I didn’t feel horrible. I’ve noticed recently that my indoor HR has been a bit higher relative to my RPE than I am used to.
Could I have held on to each interval for another minute? Maybe. I wonder whether it would be better to keep the 3 minute duration and work the intensity vs adding another minute to each.
The last time I shared a file, @trevor commented that my HR was a bit slow to respond. It looks like I did not reach a steady state in the 3 min efforts here. Is steady state the goal of these types of efforts? Meaning, maximize the time spent at 95% of HR max? If so wouldn’t a “hard start” protocol be better?
@SteveHerman, nice job modulating those efforts. The HR to me looks pretty responsive. Your first interval of course looks to be a bit slower, but on 2, 3, and 4 it was a faster response. The first 60-90 seconds will be a time where your HR works to achieve the level necessary to meet the metabolic demand, so in a 3 minute interval you won’t have a ton of time where it will stabilize. You can see in @ThermalDoc’s original post how his HR creeps to a peak HR throughout every interval with a fairly small steady portion in each one. I think about these more as the total time spent at ~90% or greater max HR.
So in terms of that, I’m always working to achieve the intended time at that intensity and would normally go first for the appropriate intensity and then build time there to progress. So in my example above I was holding around 315-320w for those 4 min intervals. The next step would be to extend to 5x4, 6x4, and then look at 5x5 and 6x5 intervals. I know around 310-315 is sustainable and extending another minute would give me the same HR response, but more time there, so that’s the rationale for moving into 5x5 and 6x5. This is something I normally work into in the spring to prepare for early MTB races. Right now, I will likely stick with 4x4 or 5x4 for a few weeks just to maintain intensity, but not sharpen the end of that blade too soon. You can see in the video from this week that I haven’t been doing that type of intensity for a while, so physically it was very challenging and that’s another reason for hanging onto something similar for a couple weeks just to get the head back in the game for this type of intensity.
Coach Ryan
Awesome, that makes total sense. I’ve never really had a good idea of how hard to go for intervals like these. Total time above 90% HRmax is a very reasonable goal for this time of the year. Given that I didn’t lose my breakfast, next time I’ll add a minute targeting 265 W, and progress from there.
@ryan, @SteveHerman @bgkeen @trevor Concerning progressing from 4 min to 5 min intervals, this reminds me of the philosophy of Canadian coach & scientist Guy Thibault, which I think makes a lot of sense. With his approach, if the goal is to reach a target power of 300 W for 10 min (as an example), the common approach might be to aim for 280 W for 10 min, then work up to 290 and then 300.
Thibault’s approach is different in hitting that 300 W target first for short durations, and then building up the duration. So start off with (example) 3 sets of 15x45 s at 300 W, 1:30 recovery. Aim is to have lots of volume at that target power, but each one is doable because they’re relatively short. But the aim is to ride at 300 W for them to train yourself to ride at that intensity.
Then, once those short 45 s (again, example) reps are comfortable/easy, move to 1 min reps, then 1:30, 2 min, etc. So overall the intensity/wattage is the same throughout, but the difficulty progresses through extending duration. I’ve tried this approach several times and think it has good merit. I did these a lot especially around 2007-2010, when I was using the ErgVideo system (one of the first to actually have Erg control of trainers, notably the CompuTrainer) and they have a workout specifically with this progression. One thing I like about this approach is that it gives you a great feel for what that wattage actually feels like, but does it in doses that won’t swamp you.
Stephen Cheung
Amazing how we are all so different while being similar in other areas.
I don’t think I’ve ever had even one workout in which my HR shoots up as quickly as Trevor’s. The ramp up is always slower.
I guess if I just mashed the pedals harder, then perhaps the response would be different, the the power wouldn’t be sustainable.
Great conversation!
I wanted to respond to everything, but there’s just been too many interesting points. So, I’ll just respond to some the thoughts about the shape of the heart rate graph. I think this conversation and the graphs everyone has provided is an amazing example of why heart rate is an important metric. If all we had was power, the workouts would all look pretty similar and most of this conversation wouldn’t have happened.
When we have the heart rate coupled with power, we can see so much more. I’m a pure aerobic time-trial style rider - to an extreme. So, when you look at my workout, you can see how quickly my heart rate responds and levels off. On some of the other graphs here, you can see that heart rate is either slow to respond or never levels off. When I see that it generally means one of two things - the workout was too hard (if it was designed to be a threshold workout) or the athlete has an under-developed aerobic system and its an area of real opportunity for them.
Having that data and seeing that heart rate response then leads to some of these subtleties that all of you are bringing up - such as should you go hard for the first minute to bring heart rate up to threshold. I don’t personally prescribe that, but my old coach Houshang Amiri, was a big believer in that approach. As I remember, he felt time at the target heart rate, not the target power was what was most important in this type of work.
The other thing I love about this conversation is that we’re talking about very simple intervals - 5x4 minutes and 4x8 minutes. But there’s so many nuances in such simple intervals. I personally think you lose those wonderful nuances when intervals get too complex.
But just my opinion. Love the conversation!
The engineer in me loves the almost mathematical precision in the approach you describe. It actually seems analogous to what is done in strength training in terms of calculating reps vs intensity. It must be important to ensure that the recovery intervals be fairly short in duration, to ensure that we are truly only stimulating aerobic pathways. Is that true?
@SteveHerman that’s one of the reasons Trevor’s 5x5 (1 min rest) intervals work so well. The rest periods are short so that it puts a very heavy emphasis on the aerobic pathway. If you were to do a “hard-start” approach to his 5x5 session, you would quickly find the last couple intervals are very very difficult at best, possibly even unsustainable near the end. So the profile would look quite different. It would still be a hard session, but the focus on the HR response that Trevor prioritizes with that session would be out the window.
Yes, it does seem to have a lot of similarity to strength training with the calculation of reps * intensity. That’s been my preferred method for ensuring overload because it’s simple and it just works. You can easily progress yourself that way.
Coach Ryan
Is this meant to be a VO2 interval? Is the HR target for a VO2 interval 92-95% of HR max? I recall a podcast in the fall where @trevor didn’t seem to be a big fan of VO2 intervals, but I didn’t quite understand why. Was it because people don’t do them properly, and/or do them them too early in the year? What is the physiologic reason why significant gains in VO2 can be had after 4-6 sessions, but threshold intervals/work take much longer to impact significant change (10-12 sessions)?
Hi @robertehall1, the episode where we discussed these intervals was 113 with Sebastian Webber. We actually discussed the name “VO2max intervals” in that episode and brought up the fact that the title gets thrown around but it’s more important to understand what the intervals are about. Sebastian wasn’t a huge fan. My feeling is that there is no one proper title, but they are frequently called VO2max intervals.
I’m not a fan of them because they are extraordinarily hard to execute. A single 5 minute effort at VO2max done hard properly should leave you pretty wrecked. To do five in a row at that intensity is almost impossible. As a result, most people don’t do these intervals hard enough.
In my opinion there are better ways to target the same energy system(s) that is more doable - two good ones are 1 minute intervals with 1 minute rests and 30 second intervals with 30 second rests.
In terms of gains in VO2max, most of us hit our peak VO2max very early in our cycling careers and its debated whether we can actually improve our VO2max at all once we’re fairly well trained. My feeling is we can budge it, but not much. So, I personally feel that while 5 minute intervals with 5 minute rests are frequently called “VO2max intervals” they don’t directly target VO2max. I think they target a variety of systems including our ability to recruit anaerobic metabolism.
In terms of why different intervals take different timeframes to see gains, it’s because they target different energy systems and some energy systems take longer to adapt than others. As a general rule of thumb more anaerobically targeted work takes less time while aerobic work takes longer.
Hope that helps!
Good stuff, thanks! Do you like the Ronnestad short stacked intervals for VO2 development (3 sets of 13 X 30sec:15sec)? I’ve been consistent with 4X8 min threshold intervals all winter. I’d be interested in more discussion on how/when/frequency to add in the VO2 intervals. Maybe an idea for a podcast or Q&A.
Hey Robert, I’m not as familiar with Dr Ronnestad’s specific intervals but they sound like a variation on Tabata’s which I am a big fan of as we move into the season. There’s a lot of different versions - 20/10s, 30/30s, 40/20s, etc. Each works slightly different systems but they all focus on our “top end” systems such as anaerobic capacity.
That type of work takes much less time to maximize the gains. I’ve seen studies that show you get most of what you’re going to get out of them after six to eight sessions.
@robertehall1I’ll echo Trevor’s response on the # of sessions. 6 is my minimum that I’ll target in a block, upwards of 8. I do like that approach of the 30/15 as the 2:1 work to rest ratio aligns nicely with achieving a high % of VO2 max as shown in Dr. Seiler’s Workshops on the short stack intervals.
Ryan
@ryan and @trevor and @ThermalDoc - so I’m reading this thread a little lagged… but I’m curious about Ryan’s comment that the hard start would throw heart rate response ‘out the window.’ I realize the original focus of the thread was on 4x4 at 108-110% of FTP kind of range, and that threshold intervals are obviously different – but the thread kind of morphed over to talking about threshold. So, here’s cheap Zwift images of 2 workouts… left one is ‘hard start’ or ‘primed’ with 30s 120% into 5 minutes at FTP, 3m rest in between at 55%. Right one is 5x5minutes, 90s rest, nominally 100%FTP, although i raised it some for reps 4 and 5. HR is more squared off in the left one. Same HR max. Pretty much the same TSS, avg watts, etc. I can tell you the primed version is harder, which is part of the point Ryan was making! The 30-60s settling back into threshold after the 120% is tough. For the 4th one I had to talk myself into it - not to worry, some sense of recovery would come despite being at FTP.
