Progressive Overload, Ramp Rate, and XSS Question

Sorry if this has been addressed. I’m new and have some questions about the Xert training planner. My questions may derive from the way Xert is designed, but it could also be that I am just confused by the interface. Bear with me and please feel free to correct any bad assumption I may have made.

Specifically, I am confused by the fact that the Improvement Rate seems to be based on time rather than XSS. If you turn up the ramp rate, then the projected hours at goal date increase dramatically. But I find this counter-intuitive because as I move from base phase to build phase I typically reduce volume to account for an increase in intensity. This helps me achieves race specificity as I approach my goal event. In other words, my TSS is constantly increasing throughout the season (progressive overload), but my volume is typically decreasing (at least to some extent) once base phase is complete. This is a common physiological approach to training that is scientifically tested and the reason why athletes use metrics like TSS and XSS rather than time to plan a season.

So here is the issue: Xert is telling me that I am projected to ride 24 hours per week at goal date. I know from past experience this shouldn’t be necessary - especially for the projected gains. In fact, I think my hours should be slightly less in the future than they are right now because I am currently late in the base phase where volume is highest.

I tried using the Automatic Assign button on the planner to suggest rides for two weeks out to get a feel for how Xert will progressively overload my schedule. Both weeks were identical. This is not good. Next week should either have more volume or more intensity than this week or I won’t improve.

I’ve read several posts that basically suggest that I should be more “dynamic” and just trust the system to give me the correct workout from day to day. That won’t work. I race bikes. I can’t afford to transition to a build phase only to find that the system is suggesting the wrong workouts in order to unnecessarily increase my time in the saddle for some arbitrary time goal.

Please let me know if I am looking at this wrong. I’m concerned that the planning function will get me where I am trying to go.

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With Xert you set it up initially then adjust it and interact with it along the way.
The Planner is for playing what-if scenarios a week in advance. You don’t populate it like a calendar-based platform.

How far have you gotten in the Academy series videos? They are meant to be watched in order (building blocks) but the Improvement series covers how you will be changing IR (ramp rate) during a progression (as you see fit) and how to use the Planner (a week at a time).
You can watch each series while you train by selecting one from the Sessions Library or watch the individual parts which are about 15-20 minutes each.

I don’t compete but you may be interested in my first full progression experiment on Xert –
Pre-Base to TED; 120+ days; 100% recommended workouts completed at 100% difficulty - General - Xert Community Forum (
Now that I understand how everything works, I am making more adjustments during each season and getting fitter and faster in the process. You are learning how to self-coach and control your training load and intensity to meet your goals.

Note XSS factors in Xert’s strain model (low, high, peak) and is not the same as TSS.
XATA is monitoring XSS to estimate hours/week but those hours vary based on the intensity of the workouts over a rolling seven day period. The pacer needle lets you how well you are doing compared to current ramp rate (this topic is covered in the I3 Academy series video).

Lots of newbie tips are also posted in this thread –
Beginner questions - Support - Xert Community Forum (

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This is a big number of hours per week, what sort of TL do you have currently and what is it forecast to get to by TED - target event date.

I think I imported a months worth of data from TP, which calculated to about 85 starting TL at about 15 starting hours.

To put it in perspective, my ATP on TP calls for about 550 to 600 TSS per week during the base period, with a rest week every fourth week. During base phase this translates to about 12-17 hours of riding per week. I typically ride several long endurance days that do not change and one tempo interval day, which gets harder each week in order to increase my stress. Sometimes I may add a second tempo ride, but not often.

My time commitment is what it is. Once I’m maxed on training time I can only increase intensity, which as we all know can only be done so much. So 15 hours is basically what I have. I know how to sort that out to make a training plan through race day, I just want to make sure Xert does to before I get too committed, because it is calling for a whole lot of hours. Like over 20 at an aggressive 1 rate.

I’ve watched them all. I may not have fully absorbed the lessons, but I have watched them.

I realize that TSS and XSS are different. I have no problem with using a new proxy to evaluate my fitness - I’m not married to TSS or the Coggin paradigm. That said, the Coggins universe has an associated training philosphy based on percentage of FTP and Zones that is really easy to understand.

Xert is interesting because the metrics appear to be based on a critical power model. I may be off base, but Xert’s TP appears to be analogous to the morton CP model and Xert’s MPA looks an awful lot like W’.

The problem, though, is that CP is just math that describe the highest power you can dish out between 20 and 40 minutes without dipping into your W’ balance. That information is, by itself, useless to inform how you ought to train because it doesn’t have an associated training paradigm or philosophy. The thing that makes FTP so appealing is that despite its limitations it has an associated training model. You test for FTP, develop Zones from the results, then ride in those Zones to target different energy systems.

CP doesn’t have any such associated system. This is probably because CP was derived by physiologists. It’s not about training, it’s about modeling current fitness. Take Golden Cheetah for instance. It models CP and is great at analyzing your current fitness based on your current MMP efforts. But it can’t tell you what to do next to improve a specific energy system or skillset.

At bottom, I’m afraid that Xert may not know how to prescribe workouts for me because I am unclear on the philosophy that is driving the workout selection - there are apparently no zones and no structured philosophy. I saw a brief mention of Seiler’s work on polarization, which is somewhat reassuring because I train polar, but then Xert selected a base ride yesterday that had me riding in Coggins Zone 4 (SMART - Song 2 - Fixed), which seems wrong this time of year.

I’d like to get an idea of what Xert will have in mind for my build phase.

Will the prescription become more intense and more polar as time goes on? If so, will the increase in intensity be met by a decrease in volume to maintain time balance? What philosophy is the adaptive training using to prescribe my workouts and is it scientifically based?

I hope this works out because I really like the idea of using a CP type model instead of FTP, but the training philosophy isn’t as clear to me as % of FTP and zones.


Analogous, but calculated differently. W’ only represents a capacity and can be spent at any moment in time. MPA isn’t a capacity, but a maximum work rate. This work rate is limited by an athletes Peak Power & their HIE (HIE is analogous to W’). E.g. if my W’ is 20kJ, then (in theory), the CP model says I can sprint for 20,000W for 1 s, or 4,000W for 5s. That’s completely impossible, given that I’m physiologically limited to ~1100 W of peak power. Another shortcoming is the fact that exhaustion occurs when W’/W’bal = 0. But because they don’t take MPA into consideration, W’bal will almost always go negative on a truly maximal effort. For example, if my W’ is 20kJ and I ride at my 4 min power until W’bal = 0, then CP model says W’bal = - and I’m completely exhausted. Xert would say that is a maximal effort, but it’s not complete exhaustion - you can continue riding above CP, it just has to be less than your 4 min power (e.g. MPA == 4 min power), so if intensity is slightly reduced, you can continue riding above TP.

I would respectfully disagree. Knowing the intensity at which MPA begins to decline is highly important to your training - knowing you can hold it for 40 min, 60 min or whatever arbitrary time value you wish to use isn’t as relevant. Because we know where MPA begins to decline, we can more accurately account for strain (XSS) applied all energy systems of your body - Peak Power, High Intensity Energy, and Threshold Power. And because we more accurately account for Strain across all systems of your body, we can effectively track training & improvement over time without needing to track time in zones.

Yup! No zones in Xert - works in a continuous spectrum, just like our body :slight_smile: We use the concept of Focus rather than tracking time in zones, since Zones (or TSS for that matter) have no way to account for the order in which work is performed, or acknowledging that work performed under fatigue (e.g. when MPA is lowered) results in more strain (XSS). I elaborate on this concept in the Improve Part 1 video - check it out HERE. In that example, I aim to point out that performing two nearly identical workouts based on %FTP zones (only adjusting the order in which intervals are performed) will result in different XSS levels, but not TSS, despite both workouts consisting of the same volume of work performed and identical equivalent time in zones. Cannot ever account for this with the %FTP training model.

Also discussed in the second lesson of the Mastering Xert videos.
In general, training progresses from endurance focused rides (performed below TP) farther and farther up the power duration curve towards your selected athlete type. You can drag the bar forwards to see how the weekly focus changes. In my example below (TED set to April 24 & athlete type of Puncheur), any HIIT training this week will be focused on my 8 min power, next week 6 min power, and the taper phase spent focusing on my 4 min power - the taper phase is spent mimicking the efforts that you’ll need at your target event, just like a coach would do.

During the build/peak phases, Xert will help polarize training by recommending endurance workouts when training status is yellow, and HIIT (with a focus determined by your training phase) when your training status is blue or green.

Not a complete answer to everything, but it sets some of the ground rules for the behavior of the platform. Cheers


What you should keep in mind is that Xert isn’t a physiological model. Instead it simply follows the math (sometimes pretty simple, logical arithmetic).

When you think deeper about MPA, you can look at it as a complete embodiment of your ability to perform - at least in principle. If you have more MPA than the next athlete at a given moment, you can ride faster, all else being equal. In Xert, MPA is calculated from 3 parameters and your power data. Granted, we can’t possibly predict your MPA is every possible condition but for what defines your power curve it works well to model your fitness. Indeed, it works well to model your intermittment MPA, with a power curve acting as a special use-case.

So if 3 variables can predict MPA, then there are only 3 systems that provide input to that power and we can assign work to each of these. Simple arithmetic in fact. For example, if your TP is 300 watts then when you do an effort that’s 300 watts, how much does your TP affect your ability to perform it? If you had a higher PP or bigger HIE, would that change this? Not at all so a 300 watt effort is governed by your TP system. Similarly if 1200W is your PP, at 1200W effort would be assigned to your PP (actually in this case, Xert splits it into 2: 300W to your TP and 900W to your PP). For intensities in the middle there is a combination of all 3.

If we also account for MPA (i.e. “strain”. MPA is, in effect, a measure of the effects of strain) we can now move to a model of training strain or XSS. We can subdivide this into each of the 3 systems. All just following the math.

When we then put these 3 separate XSS’s in their own PMC, guess what happens? There’s a very good linear relationship between training loads and each signature parameter. Crazy, huh?

So we can go from CP/W’ to TP/HIE/PP, to MPA, to XSS into low, high, peak, to identifying individual linear impulse-response relationships to predicting training outcomes and then work backwards to providing training advice.

That, in a nutshell, is Xert.

What’s more, you can validate all this yourself. No need to put trust in some scientific paper that some scientists say is hogwash. Physiology is notoriously bad for scientists having differing opinions. None of that here.


Yes. I was thinking of MPA as a capacity, not a rate. This helps to make sense of the relationships between the metrics and pulls things into better perspective.

While this doesn’t really address my concerns with the mechanics of the Xert planner, I totally agree. In fact, I was moved to try Xert because I have all sorts of issues with FTP based training plans and systems. This is just one of them. The list goes on.

But my initial concern was that the planner is predicting 24 hours per week come race day. To use Xert parlance, I will be working on my 6 minute focus zone at that time. Well, it would be crazy to put in 24 hours per week if I am working on my 6 minute focus zone. It would destroy me. Even if I glass crank it on easy days, I would be replacing two or three really long endurance rides with relatively shorter high intensity rides in the focus zone. That would necessarily indicate a reduction in volume. It is concerning that the planner is telling me that I will land on a 24 hour week when I am working to sharpen 6 minute power at that time. It makes me wonder what the planner will have in store for me, and apparently, I can’t know until I get there.

I am somewhat comforted now that I have looked through the library, though. There are some great criterium specific workouts in there. Worst case - I don’t use the planner unless it makes sense.

It’s a super helpful response. Thanks for explaining!

I am currently trying to fully understand this concept.

I understand now that MPA is a rate rather than a capacity, but how do the three variables predict it?

I’m not sure I completely follow you here. How long is the 300 watt effort? For instance, the CP curve is an asymptote, but I think everyone will acknowledge that you can’t actually ride at that wattage forever. In practice, some sort of fatigue sets in within about 20-40 minutes.

I think I’m confused because I don’t actually understand how we are defining TP? Is it the same as critical power? If so, what model are we using to derive it? If not, what is it?

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Probably good if you listen to the podcasts since we get into this more there and to check the glossary (Threshold Power, Work Allocation Ratios) too rather than rehash everything here. Episode 2 and 5 should provide some good background information.

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Ah. Great. I watched the YouTube videos, but will check out the podcast as well. Thanks!

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Just on some of your other earlier concerns:

Couple of points

  • the real measure and then driver of improvement rate is XSS, which considers intensity. Fairly sure the hours is estimated based on recent intensity only, not reflecting expected intensity at the time
  • that said, if you have been (almost) literally doing no intensity you may be surprised during build that you only get maybe one intensity recommendation a week from Xert anyway (outworking of tracking high and peak form separately, and recommending endurance when negative - easy to be negative starting at zero!). In that case your actual weekly focus will not get to the target focus. The target focus is only for the intensity days, so on average you’ll likely end up with longer focus. You can of course choose to do more intensity days a week manually (filter of use freshness feedback slider)
  • 24 hours is a lot - I think you mentioned an aggressive ramp rate. Generally that’s not sustainable or recommended so I’d lower it (at some point). Or take rest weeks, which will also mean you won’t get to 24 hours (Xert doesn’t recommend rest weeks - plenty of discussion on the forum about that)
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That’s what concerns me. At this point, I assume the projected column is hogwash because, after all, the projected date (race day) falls at the end of a taper week. Surely, Xert doesn’t anticipate that I will workout 20+ hours on race week.

I think Xert is doing a pretty good job of determining my freshness, at least macroscopically. The star color is generally accurate. Sometimes it doesn’t actually lineup, though. For instance, I’m coming off a rest week Sunday (a concept that Xert doesn’t appear to incorporate) and I also have my normal day off on Monday. Therefore, Tuesday I will be ready to demolish some intervals, but Xert shows me yellow until later in the week. It just doesn’t make sense that a person coming off recovery ride, then rest day would gain freshness as their training load increases and not be ready for intervals until Thursday.

The other thing I don’t understand here, is that Xert’s planner seems to imply that I ought to ride every single day unless I get red stars, which never happens. Does the planner assume you will ride unless red or does it eventually learn what days you take off and recovery ride?

Actually, when I turned it down to Aggressive it projected 17 hours as of the projected date. This is much more reasonable considering I am doing between 11-15 now. It’s still nonsense though, unless Xert completely ignores the concept of tapering for a race. I see that I can turn it down to taper but I have no idea how that will affect my plan at the time.

And this is all besides the fact that I don’t just have one event. I have one A race, but I have several other B and C races. Xert seems to take things day-by-day and I just don’t know if I can live without my ATP. :slight_smile:

Incidentally, I changed to continuous progression and manually populated the planner with my schedule from TP. This seems to work a little better for now, because I can ignore Xert’s periodization and all of this projected outcome stuff, but still analyze my fitness using Xert’s metrics.

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I think you need to manually change improvement rate to ‘taper’ to see the impact (but don’t race so in truth have never used it… I guess it’s a -1 ramp of TL but not sure). You can always apply your own taper at the time if you don’t like it

I suspect the long term yellow is the effect I mentioned earlier - if you do a ride with significant high and peak strain, starting with near enough zero high and peak TL you will be yellow for ages. Yellow doesn’t mean too tired to ride, just that intensity is not recommended. You can use the freshness slider to make XATA give you higher intensity if that’s what you want

The planner doesn’t assume anything actually… so if you plan a ride every day it will put one in. I think of it as a ‘what if’ tool (and so rarely use it). You need to plan your own days off, as well as recovery weeks (though if you have a lower improvement rate you may find you don’t need them). XATA kind of learns which days you normally ride longer or shorter, and is the thing to check for daily advice (and may tell you training is optional if you are ahead of plan for example)

Following your own plan is always an option. I personally don’t follow XATA particularly closely, in part as many endurance workouts are a bit on the hard side for an ‘easy’ day, but still find Xert useful, especially for intensity


Why go through all of that, though? So, the system says: “you are tired today; do this workout.” Then you press the not tired button, and the system says, “ok, here’s a harder workout.”

If I have to tell it exactly how I feel, then the star color isn’t conveying any useful information. At that point, why not just plan a training block that includes progressive overload and adequate rest and recovery?

Even if you aren’t training for an event and schedule your workouts from day to day; can’t you just skip the “freshness slider” and pick the ride that feels right for you?

I agree with this and also noticed that the endurance focus rides seems a little hard for my taste.

I think it has to do with how Xert classifies endurance focus. Xert doesn’t recognize %FTP or zones, so by definition, there really isn’t any such thing as a “tempo” ride in the Xert environment. I suppose tempo rides, as they are classically defined, also increase endurance focus, but I wouldn’t want to do them everyday unless I want my hard days to just suck.

To your point: I just finished a ride classified by TP,, and Garmin as a “tempo ride,” but Xert called it an Endurance Focus. To put this in perspective, I spent a considerable amount of time in Zone 3 and 4, and more importantly, my HR was well above LT1 for 35% of the ride. I suppose it’s fair to say that this ride benefitted my “endurance focus”, but for me, it’s definitely too hard for everyday base miles.

Checkout our blog on Sweetspot for more info about how tempo/sweetspot training fits into Xert’s paradigm.

You can create a plan with blocks of intensity and rest but if you fall ill one day or don’t replenish carbs, your recovery may not be enough. With Xert, you can instruct the advisor to account for external (non XSS) factors that effect your ability to perform and you that need extra rest. You may also indeed feel pretty good and feel confident about overreaching further than what the advisor recommends. That’s ok too. Just remember that you’re doing this.

Following a plan doesn’t normally raise your fitness to its highest levels because it doesn’t adjust to needed rest or takes advantage of additional traininig opportunties. A well designed program with appropriate advice can squeeze out everything you can fit into our schedule, rest when needed and have you attain far higher levels of fitness.

Listen to our podcast on the difference between a Training Plan and a Training Program.

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I was actually considering this yesterday. XATA recommended the Sweet Spot @90% Classic 3x20 workout. During the workout I was wondering how Xert defines SST without reference to FTP. Thank you. I will check this out!

The blog says, “The slider ranges from -60 and +60, but is set to a value of 0 by default, where is should generally be left most of the time.” But can it be “left most of the time”? Once you move it I think you are married to the new setting. Say I feel really charged up, but I have all yellow stars for the rest of the week. I move the slider some amount to the right in order to get a fresh color, and in turn the system dishes me a high intensity workout in my focus zone. Great! I complete the workout. After the workout, I now have all yellow stars for the rest of the week again. Fine. This makes sense. I am actually tired now, so the stars are accurate. However, the slider is still in the new position. I can’t move it back. If I do (correct me if I’m wrong) all the colors change again. The yellow stars are now out even farther, or maybe the planner gives me red stars because when the slider is neutral it never thought I should have done the intensity workout in the first place. Either way, if I move the slider back to the default value it will register that I am more tired than I actually am (again).

Also, it feels kind of arbitrary. Maybe it’s not, but it’s not explained in the blog. What are these units? I see that zero is neutral and + or - 60 are the extremes. But 60 what? I see green to the right and red to the left, but how do I know if I’m a +10 or a +12? I keep moving this slider around (which frustratingly is on a different page) until the darn planner gives me what I want. I have no idea how the slider, or the units on the slider, work or connect to anything that I am experiencing in real life.

It makes sense that XSS needs user feedback to deliver accurate results on how an athlete “feels”. But at that point, couldn’t you gather RPE and FEEL score for each workout, which in turn Xert can use to modify the XSS data and inform the star color to produce a more congruent result on a ride by ride basis. Or … what about maybe HRV? That would be pretty cool! :slight_smile:

I agree. This is a good reason to hire a coach rather than buy some pre-canned training plan. A good coach is expensive, though. I’m really pumped about the thought that Xert can be an AI coach that adapts to my needs. A coach ought to check in with you after each workout to see how you feel and modify your plan accordingly, though. If your coach is trying to figure out your volume / intensity balance based on calculated TSB numbers alone, then you should probably run away.

But the xata necessarily does want the hie and pp training load to be close to zero by the end of base phase for all athletes right?

Xert isn’t using AI. It’s more like a standard PMC chart, but is generating XSS, (TSS in Coggan-speak) in three categories of strain, rather than just one, with the goal of providing a more accurate recommendation than the standard PMC model. That said, Xert should have some of the same limitations that a PMC system (like Training Peaks) would have, namely, it doesn’t know how you feel. You need to give it additional information, and hence the existence of the freshness slider. I think one method to proceed is to use the freshness slider as more of a way to customize Xert, to tweak it so that its recommendations are more accurate for YOU. In other words, most of the time, leave it off of Zero, based on how you feel, and perhaps your performance. Use the slider to fine tune Xert longer-term.

Yes, exactly, if you follow XATA precisely during base, at least with my low TL. Perhaps with a higher TL you also get recommended intensity during base (mentioned above actually - song 2 was listed as endurance, but goes a bit above TP), in which you wouldn’t quite start build at zero