I’ve seen many posts alluding to the extreme difficulty of O/Us. They are classified as Threshold workouts but if you for example spend 4 of 12 minutes intervals in the VO2max zone while the HR nor the respiration rate can recover in the unders that to me is a VO2max workout. Lactate threshold is variable depending on your fatigue state and l believe you are way over your “fresh” threshold in the unders. In any case the PLs of O/Us workouts are underrated which is quite frustrating.
This should not be the case. If you’re not at least slightly recovering, you’re doing them to hard, at least the unders. But it’s also the reason i much prefer to do my over / unders at something like 110/90% then the 103/97% you’ll sometimes see. The last is just a plain threshold sesion imho.
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My point is that if you go over 100% you don’t come back to effective 90% even though nominally it’s 90% so intervals at 110%/90% are in no way equivalent to sustained power intervals at 100%. I suspect although l am not sure of it that TR assigns the same PLs to both workouts which l find unrealistic
Hey @Jose_Manuel,
Good point here!
We do actually have some higher-level Over-Under workouts where the “over” intervals are technically in the VO2 Max power zone, and you will receive small secondary VO2 Max progression increases when you pass those workouts.
Generally speaking though, the point of those over sections is to purposefully prepare you to be very “un-fresh” for the under portion of the workout.
Think of these as back-to-back hard start threshold intervals. The goal of the “over” is simply to get you into a state of fatigue that you then need to be able to recover from at a really high percentage of your FTP. The focus is to develop these systems.
It’s not likely that you’re gaining a ton of progression in your VO2 Max that translates directly to higher-level VO2 workouts, but there are cases where you deserve some credit in that zone and we’ll issue it in those cases. 
It’s worth noting that Workout Levels are currently calculated with a lot of different factors in mind, so even though Over-Unders or similarly, Microbursts aren’t exactly the same as longer, more sustained, “traditional” intervals, they could end up with similar Workout Levels as other more traditional workouts for a number of reasons.
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@Jose_Manuel there is nothing special about over/unders. If you want VO2max work then targeted VO2max workouts are more effective. If you want threshold work then targeted threshold work is more effective. Maybe the one thing over/unders deliver is to brain train yourself to be used to that level of effort.
Here is a great podcast regarding over/unders by @empiricalcycling
If you want some info on extended VO2max intervals, see my post regarding the ‘Anatomy of a 15 minute vo2max interval’ based on some of Veronique Billat’s work:
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Yeah l know Koolie’s opinion on Over unders and vo2max workouts. I will relisten the podcast but l remind that Koolie was not much fun of over unders for threshold as they generate excessive stress. In fact he is more on the side of extended subthreshold intervals. As he uses to say the success of SST is just because they are effective threshold workouts. His prescription of over unders consist of just short accelerations in the intervals. I wish it was possible in TR to select thekind of workouts in your plan you prefer to work a specific zone. Most of the times the compliance to a plan depends on your feelings. And my RPE (heart rate and respiration rate) when performing over unders is closer to that of vo2max than to traditional threshold.
Thanks Eddie! TR prescribed me O/Us in the general base phase for Masters high volume advanced level. I set up the plan to prepare a series of Gran Fondo events in late September-October.
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I like O/U for indoors because the intervals seem shorter, mentally for me it’s easier to do eg.2x 5 min @105%, 5 min @95% than 20 min @ 100% or maybe that was because my FTP was always set too high in TR because recently I did 30-65 mins (+/- 5% @ FTP and really it felt pleasant for at least 20-30 mins)
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You can always switch the phase you’re in by clicking on the phase annotation in your calendar (shown with the green arrow below) and then selecting the phase you’d prefer (shown with the blue arrow).
I’ve switched from General Build to Sustained Power Build in the past because I wanted longer intervals in my training at that time, but you can also do this for Base and Specialty phases if you’d like.
If you want a quick glimpse at what each individual phase looks like, check out the link below.
Just click on whichever phase you’d like to see and you can see that phase as a “stock” template or as a version adapted to your current career. 
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@ArHu74 absolutely! If you like doing over/unders then you should do them! Or if you just want some threshold workout variety. Bang out some over/unders.
Just don’ t to them because you think they train something that you are otherwise missing out on. If you need VO2 work, you’re better off doing targeted VO2 work. If you need threshold work…you’re better off doing targeted threshold work.
On the other hand, if the thought of doing another XX-minute threshold interval makes you want to puke…heck…do some over/unders…do some supra-threshold…do whatever gets you over the psychological hump. Just the same, if you ABSOLUTELY HATE over/unders…heck…just do some threshold work. You’re not missing out.
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Do, because he programs them all the time. 
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An important consideration with O/U’s is they can have a different training effect compared to steady threshold intervals by helping to develop the “lactate shuttle” ie. improving you ability to burn lactate as fuel. Tempo and SS “Burst” style workouts with short but hard surges above threshold would also fall into that domain
Some athletes, myself included, find the O/U’s more manageable than the steady threshold work. Some of it is mental, but how well the lactate shuttle is developed is also a factor.
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I mean, it’s better than nothing…but a typical over/under workout like picket guard where you’re at 90% for a couple minutes than 105% for a couple minutes…we’re not exactly talking about a flood of lactate oozing out of the cells. We’re talking 3, 4, 5 mmol concentrations. So the difference between blood lactate during the ‘over’ and blood lactate during a regular 2 minute threshold effort is not a lot. Probably 1mmol or less.
If you believe (as I do) that MCT1 and/or MCT4 upregulation is greatest when the concentration INSIDE the cell is much, much greater than the concentration OUTSIDE the cell…then the additional utility of over/unders for adaptation is de minimis vs just sustained threshold efforts.
If you really want to upregulate that shuttle, see my post regarding Green’s work:
Or just read the paper:
https://journals.physiology.org/doi/full/10.1152/ajpregu.00699.2007
Yeah. I think that’s 100% valid. If you like them, do them. But don’t do them because you think they provide some sort of special stimulus that you otherwise will miss out on.
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IMHO the optimum threshold workout depends also on your ftp absolute value. I know for example that pro riders with ftp over 400w rarely do supra threshold or O/Us. They prefer instead long subthreshold intervals maybe including some short accelerations. I guess that the immense stress imposed on the body by sustained efforts at such high intensities is not worthwhile the benefits if you may achieve the same by working longer at lower power.
yeah, that’s a good point, too.
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I’ve thought this for a while, but my view is that TR prescribe O/Us because their data says that the completion % and session compliance % is higher for O/U than it is for an equivalent static interval at 100%.
4x10 at FTP is a lot more daunting than 4x10 sets of 1min @ 105, 1min @ 95 x 5. So more people actually do the work.
Even if 4*10@100 is 5% better, the workout you actually DO is 100% better than the workout you don’t.
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Is that really all that daunting though, and why so?
I just hate long intervals, even z2
Just keen to chat about how strong you are mentally? To explain the obvious - 1) breaking down longer intervals into shorter ones makes the psychologically easier to chunk and 2) over/unders are easier to muscle through than 100%'s if your ftp is set too high because you can lean on upon glycolytic energy systems.
No I’m not one for talking about myself. That’s a bit narcissistic and off putting. More interested in why you find 10 mins at FTP daunting. Is it the idea of repeating it 4 times with recovery between, is it just the once, is it just the idea of riding at your FTP?