Understanding Status

[themagicspanner (Mike Lauder)]

This post was originally on the Facebook page but I thought I’d post it here now that we have a nice new forum. It also ties in nicely with the latest podcast episode.

During a recent discussion on the TrainerRoad forum regarding TrainingPeaks’ new adaptive training plans, an interesting comment brought up the issue of TSS and in particular the Form metric of the PMC not taking into account the difference between a 200 TSS endurance ride and a 70 TSS cross race: The race can leave you feeling drained even although the form number will be higher than after a long ride.

Glad to say this is something that Xert builds into its Status but I’m not sure that many users fully appreciate or understand how it works.

The following is an explanation of the inner workings of Xert’s Stutus:

Based on your Threshold Power, High Intensity Energy and Peak Power, XSS is proportioned to each of Low XSS, High XSS and Peak XSS, as shown in the first graph, taken from Xert’s online help.

As is the case with the Coggan/Allen PMC, these are tracked as exponentially weighted averages for both Training Load (CTL) and Recovery Load (ATL) with the difference being Form (TSB). Rather than taking the total XSS and using a single decay rate (42 for CTL and 7 for ATL) Xert uses different decay rates for each of components of XSS as shown in the screenshot taken from Xert’s XPMC settings page. The different components are calculated separately and then added together to give the overall Training Load.

The graph above shows the breakdown of Low, High and Peak XSS for my own 2019 data, just as it is plotted in Xert.

The second shows overall Training Load (blue) and Form/Status (coloured dots on grey). The Training load line is accompanied by 3 scaled versions: +80% (green), +40% (orange) and -40% (red). These lines form the boundaries for overall freshness/tiredness which can be one off the following:

• Detraining (brown): Form above 80% of Training Load.
• Very Fresh (green): Form between 80% and 40% of Training Load
• Fresh (blue): Form between 40% and 0% of Training Load
• Tired (yellow): Form between 40% and -40% of Training Load
• Very Tired (red): Form below -40% of Training Load

Note how the upper boundary of Tired is the same as Fresh, which brings us to the third graph: Form for High + Peak XSS.

This works in exactly the same way as the normal PMC but just looks at Training Load, Recovery Load and Form for High + Peak XSS. I’ve only plotted the Form as it’s all that’s used. Above zero in green and below in red. High + Peak Form is used to qualify the Fresh and Tired statuses:

• Fresh: High + Peak Form > 0
• Tired: High + Peak Form < 0

What this means is that even although you could have an overall form that would put you in the bracket for Fresh (between 0 and 40% of Training Load), your High + Peak Form can pull this back down to Tired if you’ve done too much high intensity work recently.

The training adviser in Xert takes your status and recommends workouts on the following basis:

• Detraining, Very Fresh and Fresh: Endurance and High Intensity workouts based on the phase of the training programme and the desired ramp rate.
• Tired: Endurance workouts only
• Very Tired: Recovery workouts or Rest only

I think this quite neatly deals with the problem that a low XSS race or hard effort can leave you in feeling tired for days but a high XSS endurance ride can leave you fresh the next day.

From a personal point of view, I must admit that this is my second time around with with Xert. Previously I had used it in conjunction with TrainerRoad and WKO and although I found it interesting, I was little frustrated with the ‘black box’ approach and a slightly clunky interface. The fact that I wasn’t really following the training adviser didn’t help either. This time I’ve gone full-in and plan to use it all the way through to my main event in April.

Taking the time to not only understand what the system is trying to achieve, but also how it’s trying to do it has been an eye opener for me. At this stage I don’t understand every aspect of it, but those bits that I have worked out make perfect sense and I hope that posting this here will help others appreciate the excellent work that the Xert Team are doing and demystify some aspects of the black box.

[xertedbrain (Armando Mastracci)]

Thank you Mike. This is awesome.

[themagicspanner (Mike Lauder)]

I just hope I got my maths correct…

Mike

[xertedbrain (Armando Mastracci)]

FAAAARRRRR more difficult to make this all work correctly than just calculating CTL, ATL and Form and plotting it on a chart.

[themagicspanner (Mike Lauder)]

I agree. Quite a few IF statements in my spreadsheet.

[themagicspanner (Mike Lauder)]

@havella

I wonder when can i expect it to “learn” and adapt.

The system doesn’t learn anything - it does exactly what is described above using algorithms.

From what I can see on your chart, your overall form is higher than TL * -0.3 (the form line is yellow) so Xert will continue to tell you to train, but only low intensity.

This means that your high + peak form is below zero. As you build High + Peak Load you will be able to train it more as it takes more to get the form to go negative.

This is one aspect where I think a little more exposure of the under the hood stuff could help peoples understanding of what Xert is actually doing.

Mike

[themagicspanner (Mike Lauder)]

Not sure what’s going on there. 10 days is a very long time to have your status as yellow.

Might be worth posting the weekly stats tab of the planner page. You can add the LTL, HTL and PTL columns to see how much of each you have.

Mike

[ridgerider2]

Looks like your cycle training is limited to three days/week riding Zwift courses and workouts sourced elsewhere. Does that mean you never select any recommended workouts in Xert to ride with EBC?
What is IR set to?
Is Freshness Feedback set to 0 (neutral)?
Are you following a progression (TED) or is ATP set to Continuous?
What was XSS, Duration, and Focus (minutes/specificity) for Suku’s Playground is Makuri?

[ridgerider2]

What happens on the Planner when you remove the Squats entry?

[ridgerider2]

I suggest filing a request with support@xertonline.com and have them take a look at your data.
I don’t understand why Focus on the weekly stats changed to 3 minute level (Pursuiter) for this week.

Is your HRM ANT+ only and that is why it is paired to Zwift?

[themagicspanner (Mike Lauder)]

There must be a very large amount of High/Peak XSS is the activity ‘Petit Boucle in France’ which is why it’s going to take so long for those ‘systems’ to recover.

Mike

[themagicspanner (Mike Lauder)]

@havella

The large High/Peak XSS activity was when I got the breakthrough on March 8th.

Ah, yes, my mistake. It was enough to take your overall focus from Endurance to Pursuiter. That’s a big step up, and when you have practically no load before that the maths doesn’t work out so well, meaning you need a long recovery time.

Mike

[ridgerider2]

Yes, good time to use the slider and you can return to neutral when it feels right.
Personalizing Xert’s Training Algorithms by using Freshness Feedback – Xert (baronbiosys.com)

Sometimes I am on the cusp and only need to slide 7-10 pts to trigger a change in form and recommendations. I have left it adjusted for a week or so before returning to neutral.
Once you increase training load and add some outdoor activities it should work fine at 0, but there will always be times when it makes sense to use it. (Predicted form does not reflect how you feel.)

[ridgerider2]

@havella

Then i got a Polar10, but Xert ECB (iphone) sometimes doesn’t pick it up or interferes with the connection to my Garmin. I don’t see any advantage of the Xert file,

The H10 supports dual device connections on BLE (via Polar app setting) as well as ANT+ so it should work fine with HR on EBC in addition to HR on Zwift.

I prefer Xert’s workout name and description when I view my activity history. Then I know exactly which workout it was, plus the Xert workout report displays on Strava. I also know the name in case I want to mark as a favorite.

Example:

Do you know the workout names you performed on March 8 and March 12?

[ManofSteele (Scott Steele)]

Looking at the weekly stats image you posted, your High & Peak Training Loads are almost non-existent - perhaps you’ve been doing a lot of base over the past couple of months?

Based on how the XPMC impulse-response model works with high/peak energy systems, adding even small amounts of strain will keep you yellow for relatively long periods of time. For example… For an athlete with a High TL of 0, an activity with even 5 High XSS will take a relatively long time to recover from, whereas an athlete with a High TL of 2 or 3 will be able to recover from 5 XSS in a much faster period of time. In some ways, it’s analogous to a brand new cyclist starting out training with no training load… they will need to start from the bottom & slowly progress their training load upwards. They won’t be able to start doing 100 mile long rides right after they start out.

I’ve been thinking about how the workout recommendations could be improved in the future… For now, my recommendation would be to use the freshness feedback slider as you start to add more HIIT into your training and slowly build up your High/Peak Training Loads.