MPA on Endurance Rides

Did an endurance ride today consisting of several sets of over/unders and my MPA never wavered a bit. There’s no way this is accurate. Just intuitively it should be clear that one’s Maximum Power Available is going to be greater at the beginning of a 90 minute workout than it will be at the end. I’m new here, so don’t have a ton of data to work with but it looks like most BTs come from a series of short high intensity efforts.

Can you get BT’s on endurance rides? You should be able to - for example if my "real’ one hour power is x and I ride 75 minutes at x, I should “be in a breakthrough” for the last 15 minutes.

Do I understand this correctly, or am I missing something?

You won’t get a BT on a LI endurance ride/workout since you’ll never exceeds TP.
The only way to attempt one would be to insert a max effort of sufficient length (or repeats) above TP to draw down MPA then exceed it for enough seconds to trigger a BT.
The four types of BTs are pull, push, multiple, and near (fakethrough). See second reference below.

Related –
Any tips on using mpa to manage endurance ride? - General - Xert Community Forum (
Why doesn’t MPA decline on longer workouts? - General - Xert Community Forum (

Reference –
Understanding MPA – A Story – Xert (
Breaking Through the Xert Way! – Xert (

In that case the modeling is not very accurate. I’ve done blocks of threshold work where I start with 3x10 and progress something like this: 2x15, 4x10, 2x20, 3x15, 2x30, etc. Obviously if I am pushing the length of time I can hold the same power out from 30 minutes to 60 minutes, there should be “breakthroughs” in there somewhere to reflect the increases in my “TP” . I know there’s a lot of science and math behind this modeling and I don’t pretend to understand all the calculations, but common sense would tell you that it’s not picking up my increasing fitness if it doesn’t account for this type of improvement somehow.

So to put this another way - according to Xert my fitness never improves unless I obtain a breakthrough, and I never get a breakthrough riding endurance. Hmmm, I guess basically the forced breakthrough is effectively taking the place of a ramp test or 20 minute FTP test. Ok, I guess that makes sense - my fitness is improving but it’s not reflected in the signature until I “test”. So If I want to measure my progress, I need to force a breakthough every 4 weeks or so (just like performing a ramp test).

After reading through the breakthrough explanations, I guess my threshold progressions WOULD result in a breakthrough as long as I’m riding slightly above TP long enough during the interval to pull down the MPA. Now I’m looking forward to my next 2x20 to see if I can reach breakthrough…maybe I’m starting to understand this.

Let’s change the word “test” to validation. :slight_smile:
Your signature is being recalculated after every activity or lack thereof (decay); no testing required.
Take a look at XO, Activities, Table. Note the figures fluctuate daily with or without validation.
Take a look at XO, Planner, Weekly Stats. Note the weekly delta for TP, HIE, PP.

If you do nothing but endurance rides below TP there aren’t enough data points to fully extract a fitness signature based on the three variables – threshold power, high intensity energy, and peak power. But calculated changes occur, nonetheless.
So yes, traditional tests (RAMP, 20, 8x2, KM) are bye-bye.
Maximal efforts on occasion to validate your signature? Not so much. They are still required. :slight_smile:

You can noodle along for up to 3 weeks before XATA will display a triangle (!) warning below your name on XO – “Hey, where’s some maximal efforts?” [My words, not XATA.]
Time to validate your signature with a BT effort. Search the workout library for “breakthrough” and you’ll find a variety. You can be said and done in as little as 10 minutes worth of max efforts during a 30 minute workout with 10 min warm-up and 5 min cooldown. Nothing like a RAMP test but you can do one if you really like them. :grin: There is one in the Coach folder based on +6% TP steps.

Let’s say your signature is dialed in (validated recently) and you will be riding an extended period without maximal efforts. Base phase for example. Change the decay method to No Decay and the calculations will be based solely upon training load. With an IR set to Moderate-2 you are increasing TL week by week, so TP will rise little by little over that period. However, how well you are responding to that TL isn’t fully known unless you validate your signature periodically. You may have improved your fitness levels beyond the calculated numbers.

Compare that to someone who is putting in base miles but also inserting a ZRL or a hard group ride with sprints on a bi-weekly basis. They may never need to validate their signature with a BT workout. For best results, they should leave decay set to optimal, so a bit of decay occurs between their opportunities to express their fitness. Their signature change graph will be more step-like.

Using Xert to Test Your Fitness – Xert (

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let’s look at your question another way. When you say over /unders what do you actually mean? Are you 10% over your TP and 10% under?

If you want to see how a workout will affect MPA and if a breakthough would be possible with your Current signature go into the workout designer. You will see your MPA curve for each interval over TP as well as the recovery aspect of MPA for the under intervals. This may graphically allow you to see exactly what you need to do bearing in mind it applies to the current signature before the workout.

It really needs for you to be significantly over your TP to draw your MPA down. There are lots of ways to see this but the workout designer is the most easy to use and understand.
for this graphic I set up a 20 minute duration but used the smart feature and entered the MMP for 18 minutes which is based upon your power duration curve.

if you can do this sort of effort and hold on for the last little bit you would get a breakthrough.
This is the best way to understand how MPA react to your unique signature. And yes you can if you are strongly motivated get a long duration breakthrough, it is just damn hard.

Play with the designer and it helps to understand how Xert works.

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To get an accurate Fitness Signature you also need to do a maximum effort sprint to set your Peak Power. Yout hen need to keep that value honest with a some sprints every now and again if you are nor regularly getting breakthroughs.

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