What FTP should I use?

Training
1

Prior to starting TrainerRoad I was on Zwift and just finished a program that ended with an FTP of 183. When I moved over to TR i didn’t update the FTP there and went straight into a ramp test (4 days after my zwift ramp test). I think I didn’t have enough rest which ultimately caused my FTP to drop to 159. Should I keep this FTP or use 183?

2

I’d use the 159w and let AT and AI FTP build from there; they should quickly adjust if the level is too low.

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3

Hmm, I’m tempted to say use the 159. But a few things first:

  1. Was the power measurement device the same for both tests?
  2. The condition the same for both? (fans, fueling, etc.)
  3. If 1&2 are a yes, have you done any workouts using the 183? If you’ve done Threshold-ish workouts with it and it felt right then I’d go with that
  4. What did you do between the two tests?
    – 4 Days is definitely enough to recover but if you did a bunch of riding between then it could simply have been a fatigue thing.

Though I’ve never used zwift, I think their FTP test is a ramp using steps of a constant wattage (like 20W IIRC). If that’s the case then it’ll be a different test for people with different FTPs (20W is a much bigger step for someone with a 170FTP vs someone with a 350FTP). So it’s possible that TR’s test was longer and thus built additional stress within the test. If that’s the case then I might lean more toward the TR result. But if any of the 4 questions above point to another obvious reason for the drop then you could take that into account.

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4
  1. Power measurement was exactly the same using tacx neo 2t trainer.
  2. Fueling may have not been the same in terms of nutrition as I was doing a lot of traveling.
  3. Prior to starting the zwift training program I did an ftp of 180 and used that for the program. Which included threshold work.
  4. Between the two tests recovery-wise, I did not do any physical exercise.
5

I had the exact same thing happen to me: FTP in zwift was 212 - ramp test in TR (when I was just starting my structure training journey) was 189. It was a little demoralizing but I took the 189 and the subsequent workouts were plenty hard. I’ve “made that all back” (in quotes as who knows the “true” value due to differences in methodologies and such) and then some while on structured training.

With AT, I think that either way you go though the adaptations should keep you covered.

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6

Trainerroad workouts and AT work best with the TR ramp test. I would go with the TR number unless you know you underperformed and let adaptive training take it from there

7

If it really bothers you then test again but you’re not supposed to be super fresh anyway when you take those tests.
There’s plenty of posts on here where people train to the higher number and it soon comes back to bite them.

8

I’d take a rest, retest, and start fresh.