To find where your limit would be would require training exclusively for raising FTP for years, right? I don’t think Fabian Cancellara or Dave Zabriski know what their end limit could/would be, let alone us with day jobs that don’t involve racing a bike and testing facilities (well, and coaching too).
There is no way to figure out my end potential. At 38 though, there is still room for major improvement as I’ve only been ‘training’ for 6 years (fat couch potato in a previous life). Whether or not I can raise my FTP by 100 watts is yet to be seen due to health, motivation and lifestyle factors. Add to that the fact that I don’t train but once to twice per week for FTP.
Genetics are carved in stone to point, but I’m going to assume that very very few people in the history of endurance or power sports have reached the end all of their potential limit.
Your quote:
And finally, how do you determine when you get there? If your FTP numbers have been at 290 watts for 4 years and you are 39 years old, is it safe to call that number your genetic limit?
Too little information to go on, but I would say no. Has training changed over those four years? Nutrition? Coaching? A person could quit riding anything over an hour. Stop endurance riding completely and focus on FTP raising (that would hurt). Until that happens and one has perfect nutrition, coaching, recovery, etc, we’ll never know.
Good topic.