I hope you update your training zones regularly (8-12 weeks with regular training). But how you determine your zones matter too. Recently, I had an athlete that was able to do a Lactate Test (LT), followed by an FTP test 2 weeks later. If you plugged in his FTP number (298W) into the calculators, it would say his top of Z2 power (76% of FTP) is 226W, while his LT results had top of Z2 at 200W. As you know, 25W can be a big difference in effort. What is worse, the calculator