Just to clarify, there is definitely anaerobic contribution to the MAP portion and for some athletes it can be meaningful. The sprints will use your stored creatine phosphate in the muscles but two sprints are not nearly enough to fully deplete the anaerobic stores especially given the recovery afterwards (i think really by “deplete” what we mean here is, fully exhaust the larger motor units that predominately make power anaerobically). Remember that motor unit recruitment and how those motor units generate power are a continuum so “MAP” is really just shorthand, partially functional shorthand for a set of power targets for certain types of workouts, not a discrete “energy system” that can be measured. Other way to think about it is, if there were no anaerobic contribution to your MAP, then it’d pretty much be your FTP.
So here’s what i think is likely going on here. You might have overcooked the MAP portion of the test and you could definitely eke out a few more watts with better pacing, but you didn’t really do it wrong in a way that you’d expect to blow up your FTP. After all, max is max, whether you start to flag at the very end of minute five or you flag earlier because you paced it wrong.
Rather, ramp tests are known to often overestimate FTP for anaerobically strong athletes. Ramp tests do not generally measure your FTP; they measure your performance on the ramp test, and then apply a formula to it to estimate your FTP. My understanding is that with HM, they’ve tweaked the standard ramp test to make it spit out a more accurate estimate, and that’s probably true, but still doesn’t mean it’s a perfect estimate for every person who tries it.
So, where am i going with this, you might ask? I don’t mean to come off as dogmatic but in my view there is one really good way to test whether what you think is your FTP is actually your FTP, and that’s the long-form test. On a day that you’re fresh enough, decently rested, fueled and hydrated, hop on the trainer and do this:
i. try to ride at 292 for 35 minutes
ii. if you succeed, bump up the power by 10 watts or so every five minutes
if you can get through step i and maybe even a couple additional bumps in ii, then it’s likely that your FTP is 292 or thereabouts, OR potentially that your FTP is lower but your time to exhaustion (TTE) is fairly long, so you were able to work above FTP for a good chunk of time (35 minutes!). If you’re very well aerobically trained, this could be the case, and to get more accurate, you dial it in by trying to extend step i longer (to like 45 mins plus) or raise the power, and see how it goes. This part is more of a judgement call, because FTP has no set TTE that holds for everybody (i.e., it’s not 60 minutes, that also was just a way of estimating it).
Alternatively if you can’t hold 292 for the duration of step i, then 292 is probably not your FTP. Which is fine, you need an accurate target to work at, not an ego number.