Can you recommend a workout that can increase zFTP? Tks
zFTP is your critical power.
Doing any real work 10% above your zFTP should be around your hour power, and of course any amount of work done further above that will be working anything between your MAP / Vo2 power out to whatever you’re specifically wanting to focus on.
You can increase your zFTP basically from increased power outputs from the 15-45 or so minute mark (someone here will have better numbers but anywhere in there will do it).
As far as recommending a workout; one in particular won’t do it, to get there it’s best to work all ranges; thus a multi week program would be the only way to do it.
Some of the classic training plans like Build Me Up have had great results from all comments I’ve come across from users that have done it (I did the longer one back when I started Zwift).
Because zFTP is calculated from your PRs in the last 90 days at a variety of durations, if you want it to be accurate, you will need to have true PRs all across the power curve (I think it stops at 50 minutes IIRC).
Keep in mind that zFTP is only intended to determine racing category, it is not the same as FTP, so my question is why do you care about having a higher zFTP - what do you hope to get from making that number bigger? For example if what you actually want is to shift into a higher category, increasing your zMAP is often an easier way to get there. But if you explain the motivation I might be able to say more.