Small FTP Increase Question

I came back to training in December with a TR recommended FTP of 220. I have been doing the low volume plan, but adding in some Z2 and subbing in spin classes…etc. on some of training days.
I noticed my non TR workout on Friday had an IF of 1.2 with a FTP of 220 and when I ran FTP auto detect two days later it detected 229.

I am not complaining as I will take any bump I can get, but I am not understanding how a person can do a workout of approx. 1.5 hour and have an IF of 1.2, but the FTP only increases 9 watts.

Can someone help point me in the direction of what I am failing to consider/not understanding?


What was the average Power? IF can be driven by short, high power spikes, so average power is better to look at if you think your FTP went up.


Looks like it was 166 average with lots of spikes/intervals.

I’ve heard workouts like this described as “FTP Busters” as the IF appears to imply a significantly raised FTP, but in actuality it is just the nature of how IF is calculated. IF = NP / FTP, and NP uses quadratic of FTP in 30 second chunks. So FTP spikes can artificially raise NP

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Based on what? Past rides?

Yes. I assume it took past TR rides to make the suggestions as I did not do a ramp test.

IF is a useless metric. With the new WL’s its no longer needed. Weighted average power is useful over longer rides.

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which implies there is nothing in that ride to help you triangulate FTP.


Ok, well maybe then the FTP increase was more due to that initial estimation being off than the result of the mentioned workout?

Just guessing, btw. :slight_smile:

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