Originally Posted by
gregf83
The original point of FTP was that it was a relatively simple measurement to make in the field. It was never a lab based metabolic measurement. I don't think there has ever been a definition of FTP that would support riding at 105% for an hour. People that ride over 100% for an hour simply have their FTP set too low which is not uncommon as FTP is not constant over time.
I believe that it was originally a lab based thing (the point at which you start to accumulate significant bloodstream lactate). The field measurements are a way to do this determination in the field without a lab. I have no idea how different they might be in some cases. And I agree that 5% more power (as opposed to 5% longer) is a big step. dave