Hey Bryce let me try to explain the problem with that general recommendation for some of us… starting with this TR blog post about VO2max workouts:
In comparison to VO2 max, your FTP generally falls between 78-85% pVO2 max, with pVO2 max falling around 118-128% FTP. This is the reason why VO2 max workouts from TrainerRoad use 120% FTP as the basis for short, intense intervals. Erring near the lower end of the spectrum, these workouts allow you to do more work while still at a very high percentage of pVO2 max. That’s what really matters — spending time training at high percentages of pVO2 max.
(except the recent podcast 191 VO2max deep dive part 2 clarified what really matters is spending time at high percentages of max aerobic uptake)
- vo2 target of 128% ftp = 1/.78 when ftp is 78% pVO2max
- vo2 target of 118% ftp = 1/.85 when ftp is 85% pVO2max
What happens when you fall outside the norm, and “erring near the lower end of the spectrum” is still too high?
Lets run some new numbers… This year partly due to focus on non-cycling knee rehab, my pVO2max dropped like a rock and is uncomfortably close to ftp. Last summer my ftp was something like 85% of pVO2max, and this year ftp has been hovering around 90% pVO2max. One indicator of being in this detrained pVO2max state is a failed ramp test.
Doing the math when ftp = 90% pVO2max:
- vo2 target of 111% ftp = 1/.9 when ftp is 90% pVO2max
so for all outliers with low “field/workout tested” pVO2max relative to ftp, erring near the lower end of the spectrum means reducing target from 120% to 111% if ftp = 90% pVO2max. And then during the workout your 5% reduction comment applies.
p.s. I’m using failed ramp tests as a leading indicator that pVO2max is falling too close to FTP, and a follow up “repeatable power at vo2max” workout is required. Once pVO2max is detrained, it is time for a vo2 booster block to get back on track.