Originally Posted by
PeteHski
This is a fundamental limitation of both ramp tests and a single FTP metric to set all your power zone targets. It's always going to be a generic guesstimate of your abilities. I think the 20 min test will improve your FTP metric, but it still has to guess what all your other power metrics are i.e. VO2 max, AC, NM and your recovery times between repeated efforts. That's one of the reasons I moved to Sufferfest (SYSTM) for interval training because their benchmark test measures your 10 sec, 1 min, 5 min and 20 min power to build a more comprehensive power profile with which to set interval power targets. It works well, but the benchmark test itself is not something you would want to be repeating bi-weekly! So they do also have a ramp test for interim progress checks, which in itself is more sophisticated than the simple Zwift ramp.
Agreed re: limitations. Fwiw, you can link your Zwift account to
ZwiftPower, which will extrapolate your 15s, 1m, 5m and 20min "bests" from races you've completed on the platform - expressed both as wkg and watts. Your 20min "best" from any given race determines your race category and will likely resemble what you could achieve during an outdoor 1-hr threshold effort (in my case ~20w lower than results from the non-ramp Zwift ftp test).
My winter bi-monthly 20min effort is a 4x5 threshold session targeting my ZwiftPower "20 min best", along the lines of the description below. This should feel more manageable (lower avg hr) than a ramp test. My current ftp equates to 4.6 wpk, which is good fitness for my age but a ways off from where I was in my 30s. Any workouts I do now are mostly about limiting VO2max losses.
“Smashing it” for 20 minutes might sound pretty straightforward but, to get the most out of your test, some intelligent pacing will be required. When prescribing a Threshold Power test to my athletes, I encourage them to break the test down into smaller, more manageable chunks, e.g., four five-minute efforts. For each five-minute time period, have a soft goal for average wattage. Trying to increase the average power for each five-minute segment (compared to the segment prior) will go a long way to helping you achieve proper pacing. As you get to the end of each five-minute portion, make an assessment based on your rate of perceived effort (RPE) and ask yourself, “Can I keep up this intensity? Can I increase the intensity for the next five minutes and the remainder of the test? Should I back off or maintain intensity for the next five minutes?” ... Remember, the goal of testing isn’t to meet a particular number but rather, to measure the best performance you can do on a given day. Being in tune with your RPE is critical."