Thanks for posting, impressive and a valuable insight.
Why the 5 minute effort in the warmup?
Just warming up the legs so you’re not fighting stiff legs when doing a threshold effort.
Got your email about adding FTP. Does your FTP estimation depend on it? Because it seems the assumption that people have spiky power data is the reason for my disappointment - I didn’t have to add historical ftp to Xert or WKO in order to get reasonable FTP estimates (reasonable when there were enough hard efforts). Also even after adjusting ftp, and leaving power spike at 20%, the intervals.icu ftp estimate still seems too high. Do you have a link to the model used? Sorry if I missed that while browsing intervals.icu. Thanks!
The power spike detection depends on FTP because it uses your assumed power curve to spot spikes. The FTP estimation does not but if the spike detection is “fixing” things it shouldn’t it won’t work well. If your power data doesn’t ever have spikes you can turn of detection globally. Intervals.icu uses max efforts of at least 3 minutes to put you on a pre-defined power curve (same as 75% of 5m power, or 95% of 20m power but generalised) and uses Morton’s 3P model parameters for that curve for FTP (using FTP = CP). You can see the model curves on the /power page.
For myself it gives numbers 1-2% lower that Xert and both are reasonable estimates to set zones for my training. When Xert says “breakthrough” Intervals.icu says “FTP up” so I think Xert is doing something very similar. If you add the W’bal series to an “FTP up” ride and enter W’ (get it from /power page) you can see W’bal going to zero or below at the “FTP up” moment. At this point you have exceeded the model prediction and so your FTP has likely gone up.
You can adjust the minimum duration that Intervals.icu uses for FTP estimation in /settings. Maybe 3 minutes is too short for you, 5m might be better.
How much too high is the intervals.icu estimate and how does it compare to a TR ramp test (if you have done one)?
The whole business of estimating FTP is very interesting and a lot fuzzier than what I thought before I started working on this (last December)!
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intervals.icu gave 7.6% higher estimate versus Xert and WKO and Garmin.
Details:
- Intervals.icu gave me 298W estimated FTP
- After that ride Garmin gave me 277W, Xert bumped my FTP to 277W, and WKO4/WKO5 show 277W mFTP. That ride was my first attempt at an “all-out” 1 hour ride, looking at power curve for the ride the 1 hour best power (average) was 271W but it included 50 seconds at a stop light (the last light leaving town)
- Two weeks earlier I did a 10 mile “Merckx class” TT (road bike, no TT gear) at 281W / 27+ minutes. Prior to the solo TT was with a group and did some hard clearing efforts to reduce anaerobic contribution.
- Wasn’t using TR that season (2 years ago)
Thanks for Morton 3P model details!!
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There’s no chance you have a duplicate ride in there? I’ve had that cause issues with the model in the past.
None.
Hmm. I think I know what the issue is and how to fix it. Most of my dev and testing (and feedback from athletes) has been with durations under 20 mins + my curves have a drop off at that point (because not many people actually try do a 1h TT to test FTP - that must have hurt!). So its overcooking FTP for durations more than 20 mins. Tx for all the info!
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So I did a second attempt today. On Tuesday I tried it with 250w target and failed about ten minutes into the 100% segment. The FTP was 5w lower than my season high but I was coming off a two week break so that might have been hubris. I also just didn’t quite remember what threshold feels like or maybe I never knew because of overestimated ftps from the ramp test.
Today I tried it with 240w. About ten minutes into the test, I realized that I had done something around 243-244. Every once in a while I drifted a few watts up and could actually feel a difference so I forced myself back to 243ish. The last ten minutes of the middle interval felt easier and when the ramp came around, I stepped it up to 252ish for a few minutes. With 2 minutes to go I felt like I can raise it a bit more without it just being a sprint or whatever.
The average of the three test intervals is 244w. Mostly I liked the format. My TR profile is private, but here’s a screenshot of the workout summary with relevant intervals:
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Nice work!
I tried the Baseline 35 - 40 minute assessment this morning, first impression is that I like it over any other assessment I have done. It will be interesting to see how I feel over the next few days but I can’t see recovery being anymore or an issue than any other Threshold testing or the 20 minute assessment.
Some WKO Stats before the assessment:
- TTE = 38:30
- mFTP = 247 (it was 248 yesterday)
- sFTP = 252 (reduced from 258 earlier this week as after the Worlds as I’ve been off for 13 days except two sessions one SST and one 45 level 2, and had a cold)
- Stamina = 83
- FRC = 12.5kJ
I did the first 10 @ 92%, next 15 @ 100% Target FTP which was 252w, and then ramped 1% per minute until failure
RESULT
- Managed 38 minutes 10 seconds average 253w, NP 254w (prob because a spike at the start)
- Max 20 minutes 264w, 95% ~ 251w
- TTE in WKO increased to 40 minutes 2 seconds, i.e +1:32
- mFTP increase by a watt to 248
- FRC and Stamina stayed the same, as you would probably expect
So I’ve got two numbers and could either use the average of 38:10 i.e 253watts or 95% of Max 20min 251 watts. I have my mFTP set to 252 watts and I’m leaving it there as its between the two.
Okay, I’ve only done this protocol once but would I recommend giving it go… YES!
Why?
- Time will tell but my guess is there is less chance of a bad test (unless your target FTP is way off, you won’t go off to hard)
- Seems accurate, for me anyway
- You get a good threshold workout
- You also get a good idea of you 20 minute power
- You get information on VO2Max from the ramped effort after the first 25 minutes.
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I have sorted out Intervals.icu FTP estimation for efforts longer than 20 minutes:
- 10 mile TT on 19 Mar 2017: FTP +35 to 272w from 29m at 285w
- 1h TT (actually 55 mins) on 9 Apr 2017: FTP +1 to 270w from 34m at 281w
Now if you do a 1h TT then that will be your estimated FTP. I could have tweaked things up a bit to get exactly the same numbers as the other tools but I like the 1h TT = FTP result that this gives.
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Looks great, thank you! Now I just need to work hard and get back to 270+ — back to the future!
Can someone please explain how you download this app as I can’t see a link anywhere other than a link to Strava?
Thanks
Coming back from injury and getting a bead on where I am. Model had me trying to hit ~215 for 30 min and came in just under that. Paced to RPE and just let it do what it was going to do.
https://www.trainerroad.com/career/epvanhouten/rides/68089936-morning-ride
I’ve been on that page hence me knowing about the Strava link. How do you download it from that page?
So where is the page for signing up? Why is this such a difficult question? I can’t see anywhere on the site to sign up.