Originally Posted by
DaveLeeNC
I believe that it was originally a lab based thing (the point at which you start to accumulate significant bloodstream lactate).
You are incorrect. There are many lab-based metrics for when someone exceeds a quasi-steady state (lactate threshold, anaerobic threshold MLSS, OBLA, etc.). FTP was introduced as a simple field-based metric to replace the need for lab testing. I was there when it happened.