Is PP a theoretical number?

In Xert my peak power is set to 1548W, which is about 100W more than what I think is a realistic 1sec max power I can produce currently.
I have about 3 years of training data loaded into Xert, and have been removing some spikes in previous efforts manually, that were over 1600W.

I realize that the chaning the PP value will alter my training and BT’s, so am in doubt what I should do?
For reference:

Have set to slow decay as I train 4-6hrs/week and find that TP does not reflect my training unless I do a BT specific workout every 3-4 weeks.

PP is both actual and calculated. A calculated PP occurs during a BT effort where you sprint during a maximal effort while under fatigue. The theoretical number could be higher than the actual number you have achieved in the past.
OTOH if you suspect power spikes in your historical data an easy way to handle that is to view the activity table, enable Max Power using Edit Columns, sort by that column, mark any problem entries, then select Flag in upper right. That prevents those entries from affecting signature calculations.

PP is the least sensitive number when it comes to the signature algorithm. For example, it is not uncommon to have a lower PP during indoor season and bump it back up as soon as you head outdoors. You don’t want a large difference while training, but within ballpark is sufficient since Xert is recalculating your signature after every activity or lack of.

You can use Advanced MPA to make signature adjustments. See this article for details –
What is Advanced MPA? – Xert (

Also, podcast #17 discusses signature adjustments and handling errant data –
The Xert Breakthrough Lab Podcast – Xert (

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Will it be much easier to drag MPA down during a sprint? You might 10% above your PP but that will only be for a few seconds. Yes you might get a PP BT but that doesn’t mean that much overall.

To see this in action try this experiment –
Go to XO ( and click on your last BT which is linked below your name.
Select Advanced MPA, then click Previous button to view details of the BT event.
Now bump up the PP by 100 or even 200 watts and click Refresh. Not much will change other than the fact MPA draws down from a higher ceiling.
Now try the same thing with TP but just a few watts, say 5-10. Notice the difference.

PP is fairly elastic. The difference in your indoor and outdoor max power is likely 100 watts or more, but that isn’t going to adversely affect your indoor training at the calculated TP. When you do head outdoors PP will rise accordingly.
It’s the rate of MPA drawdown, rather than the height that’s more important. Plus, how often can you draw MPA down and recover (repeatability) which is reflected in your HIE.

If you feel your PP is significantly underestimated, you could raise it, lock it, and move forward from there. Otherwise, you should attempt some sprints now and then regardless of the path you are taking with your training. There are workouts in the library for this purpose. Filter by “Road Sprinter”.
Here’s one created for the Wednesday Sprints group session: Xert - Workout Designer (
Note the description.
Sometimes I make it through the first set, but after that 20s is a tad too much but I’ll try. :grimacing:
There is definitely a benefit to challenging your peak strain like this regardless of your sprinting ability. You could do something like this outdoors, but definitely not at the end of a 5 hour ride. :wink:


Although I certainly see the logic behind taking longer to pull MPA down from a higher value…You’d be surprised how little a difference in 100W (even 200W) will make in your TTE at supra-threshold efforts.

You can test it yourself using the workout designer! let’s consider 2 athletes holding 300W efforts to failure:

Athlete 1: 1400W PP | 25kJ HIE | 250 W TP

TTE @ 300W = 8:10

Athlete 2: 1200 W PP | 25 kJ HIE | 250W TP

TTE @ 300W = 8:05

So, despite a 200W difference in PP (but an equal HIE/TP) these athletes will reach failure within 5s of one another in a steady 300W effort. I don’t think 5s is a massive difference (1% difference, actually).

However, a 200W difference in PP will make a huuuuge difference in their power curves for efforts < 30s or so.


I’ve found the same thing to be true, which is that my PP has always seemed to be 100 to maybe sometimes 200w higher than what I’ve been able to hit as a peak, with some caveats. I can’t honestly say I’ve ever spent a whole workout trying to hit it, but I have done plently of races where the motivation was there. When I’ve artificially lowered it, it’s messed up my HIE and TP, so I just leave it.