Yep - I just did a quick search. An issue with the search tool is the descriptions aren’t consistent so not all 30/15 come up with that search. Sometimes the description is 30 seconds, sometimes 30-seconds… etc
I might try Rattlesnake and compare TIZ to 4x8
yup.
Let me know how it goes with Rattlesnake, when I have enough max efforts I’m using WKO4/WKO4 to estimate time in vo2max 
I did Rattlesnake for the first time yesterday - I usually do Dicks -2 or -1 (the 5x8 with 5min rest version). RPE on Rattlesnake was definitely lower than either version of Dicks. I don’t have fancy software - ok, I do, but I gave up on Macs and haven’t ported my WKO license to my wife’s PC - but I think over all, I got HR up quicker and stayed around 90% HRmax especially in the second two intervals. So I’m pretty happy.
If you’re a Dicks guy, give it a try 
I think i got the answer i was looking for in this article from wattkg.com about Rønnestad 30/15 workouts. So my conclusion is that higher power output counts for something, not only time above 90% HRmax.
" 2) Furthermore, Rønnestad and colleagues highlight that it has been suggested that time spent at high intensity has an additive effect on muscular adaptation. It is not unreasonable to assume that the short intervals involve a higher power output than what can be sustained for 5 minutes of consecutive work. This might contribute to larger training stimulus than the 4 x 5 protocol."
Final answer:
If you possess a heart rate monitor or power meter, it would be a neat little experiment to see for yourself.
I also tried Rattlesnake the other day and found it too easy - the power drops off too much. The 1m hard starts and first 2-3 rounds felt about right (i.e fairly horrible) but I started to recover after that.
I turned it up a bit towards the end of the first set, but much more and I’d struggle to get past the initial effort in later sets.
The other thing might be the rest intervals being so easy… the usual prescription is 50% of the work interval. These are more like 30%, so you’re getting a lot more recovery in those 15s than if you were force to recover up at ~60%FTP.
That is an interesting comment, someone just posted on the WKO forum about prescribing rest intervals up a around SST, sounds fun 
Can’t remember the intervals off the top of my head.
I made a version of Rattlesnake which eliminates the rest intervals; it’s now a continuous descending power interval.
The other thing I wonder about TR’s general tendency to have very easy rest intervals, is that it must make the start of any interval at any intensity more anaerobic. It makes the interval easier to complete, but it may also materially affect the stimulus.
Its important to be really well recovered for certain types of work (e.g. building anaerobic power), but I think that in a lot of cases you’d better off recovering at 50-60% FTP to keep the aerobic system going, particularly mid-set with repeated short intervals, and between any longer intervals under threshold and perhaps even the lower end of VO2max work.
For instance, take workouts like Chimney/Owl, Buffalo… all those Hard start S/S or Threshold workouts… that are supposed to mimic attacking in a race and then holding a TT effort to stay away… except when did anyone attack in a race after 6 minutes at 40%FTP?
Bit of a tangent there, but to bring it back towards the topic, there’s not been much discussion of rest interval prescription even though it can really change the nature of any workout.
For those targeting time above a HR target, maybe a ‘recover until HR gets under X’ type prescription would help?
The workouts are optimized around time in zone. If you aren’t getting a solid recovery by working in z1 it is going to compromise your ability to hold the target zone. If you’re doing 30/30 repeats and you think that spinning in mid to high z2 is adequate recovery… you are doing the interval wrong.
The target of these intervals is the aerobic system. The aim of this type of workout isn’t to do as much time at X watts as possible, its to work as long as possible whilst your aerobic systems are stressed close to maximum capacity. If the recoveries are too long and/or too easy relative to the work interval length/intensity, that won’t be happening.
For a lot of people who are well trained, 30/30 is just too much recovery even if the work intensity is really high, hence the prevalence of 30/15s and 40/20s in literature.
You’ve never done Phoenix + 1 then.
I’m in the off-season now and wanted to try a polarized approach so I’ve been working with these two variants while adding in more Z2 volume. They seem to produce a similar HR affect. (I’ve never posted links before so not sure if I’m doing this right.)
Seems to be going well so far and need to tweak things a little as I go. I think this stuff is highly personal. I really like the variation in the two workouts as doint the same one over and over would get boring. It also seems fitting in XC MTB applications.
https://www.trainerroad.com/career/lancestrum/rides/66101318-5-x-8-107-
https://www.trainerroad.com/career/lancestrum/rides/66318064-3-x-30-15-130-w-hardstart
Yes, the way to ‘fix’ a 30/30 is to increase the work or decrease the recovery. If you increase the intensity of the recovery you’re not doing the same thing anymore.
Yea, because their none of their sustained power plans, or any of their cycling plans, build you towards it.
Here’s one of the key pieces of literature showing the benefits of short intervals.
‘with recovery period being 50% of the work duration at intensity equal to 50% of MAP’.
MAP in this study was from a 25W/min ramp test (so will be higher than the end of a TR Ramp test for most as that’s only 6%FTP/min, ) So likely in the 135-140% FTP area or higher.
That would mean if work intervals were at say, 140% FTP, Recovery would be at 70% FTP. And that’s for 30/15s not 30/30s. These are hard.
30/30s with 40%FTP recovery aren’t going to get a lot of people up in the high aerobic range we’re talking about targeting… as seen with the Taylor -2 workout from the OP.
There are multiple levers to pull to increase the aerobic stress… the length of the work interval, ratio of Work:rest, the work intensity and the recovery intensity. Its just that TR don’t give you to any options to tweak the latter, even though their prescription is non-standard.
Full version of the paper available here… Optimizing Interval Training at Power Output Associated With... : The Journal of Strength & Conditioning Research
140/70 at 30/30 would be a pretty good workout and probably tweak the right levers. I imagine the first couple repeats would be heavily anaerobic dominated so you would need to suck it up and do sets of 8-12 x3.
120/50 30/30s just… aren’t very good.
Why not give a workout like Rattlesnake a shot and actually see how much time in zone you have?
This is such a good reply, thanks man!
Sorry, meant to respond at the time.
It’s interesting that your heart rate comes down so quickly after the initial effort. Certainly not my experience, but we’re all different.
Are you happy that Xert has a good estimation of your threshold power? If i’s too low it could allow you to start to recover.
Might be worth posting this on the Xert user forum.
Mike
Just a thought… Vo2 gains would corralate if you were running or rowing as long as the work and HR requirements are there… Assuming the gains are purely for oxygen intake nothing to do with the legs endurance or economy for cycling?
Since technically you can get more “vo2” oxygen intakes with more body parts working, and making off season, off the bike training more fruitful…