FTP contra TP contra TSS contra XSS

After a disastrous year (illness++) my FTP sank, which is understandable.
So to establish at what level I am now, I have taken 2 FTP tests admittedly the not so akkurat Ramp test. Each time I was recording a 195 FTP.
So then I joined Xert last week expecting to train at that level, but lo and behold Xert gives me a TP of 152 which when doing a workout yesterday with a TSS of 66 (TrainingPeaks) I only achieved 39 TSS (again TrainingPeaks).
Can anybody help me understand this as I am really struggling coming to terms with Xert?

Hi @traveller Welcome to Xert! Hopefully I can help!

It looks like the ramp test was a little while ago & that Xert did have a similar FTP at that time resulting from your ramp test (looks like ~185 W from Xert).

However, Xert knows that an athlete’s fitness can increase (or decrease) when they train (or take a break from training). Because there was a bit of a break from training - which is totally fine - Xert allowed the Threshold Power estimate to decrease. If you think the TP value is underestimated, then it might be time to try and update your signature with a Breakthrough effort! This could mean a ramp test or 20 min test (if you enjoy those), or could just be a hard effort during a group ride, a PR/KOM effort on your favorite Strava segment, or even a Zwift (or real-world) race!

Hope this helps! Cheers!

In addition to the excellent advice from @ManofSteele there are a number of Breakthrough workouts. Search workouts with the term ‘Xert Fitness test for Breakthrough’

I recommend the 30 minute test shown below. I always get a BT and it is quite an easy test.

Hi and thanks @ManofSteele, I’m grateful for all help to understand Xert at present. The tests were 2 and 3 months past. I had expected to be somewhere near those efforts. However, having said that, I am still struggling with last years fatigue problems so Xert could be right. I’ve purposely been taking it easy and also doing aerobic rides and gym work.

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Thanks @johnnybike, I’m just going to follow through on a few more weeks of very easy aerobic workouts to see if I can get rid of this fatigue that is pestering me, then I’ll try the breakthough workout you suggest before starting to build again.

2…3 months is sufficient time to lose a lot of fitness if you don’t keep up with training, even more so when being sick. Been there & done that.
Xert is also probably not “right” in the strict sense that it now magically knows your current TP/signature.
It just applies a gradual decrease to your fitness signature over time, depending on the development of your training load.
What Xert is inviting you to do, by making it easy to achieve, is to update your signature with a fresh breakthrough.

But if your are not at 100% health you might want to wait with that. In that case I’d personally do the same what you said, stick to easy endurance rides where I don’t feel worse after then before, without caring for my exact TP/fitenss.
Until I feel fully recovered.


Xert won’t schedule a BT workout automatically but alerts you when your signature becomes “stale”.
You can select a BT workout anytime you’re feeling fresh and want to validate your signature. They range from 30 minutes to an hour and are nowhere near difficult as a RAMP test.
As @johnnybike suggests, search Workouts Library for “fitness test”. Ride entirely in Slope mode except perhaps warm-up and cooldown.
On any intervals designed to bring you to a failure point, spin up (stand if you want) and go for broke, exceeding target watts and duration if able.
If you achieve a Near BT your signature is close to dialed in. If no BT your signature is likely overstated or you simply weren’t fresh enough that day to test your mettle.
So health first and when you’re feeling better consider a BT workout. I don’t do them very often but it’s nice to confirm your signature is dialed in.

Reference –
Breaking Through the Xert Way! – Xert (baronbiosys.com)

Thanks @ridgerider2 . Good advice. I’m concentrating on just that, a slow progression back to “normality”. Then will try a BT workout in about 3 weeks.

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