Originally Posted by asgelle

Another reason Andy has given has to do with with a riders glycogen budget. From Andy, although riders have vastly different aerobic capacities, glycogen stores and the ability to replace glycogen don't differ that much from one person to another. That means that both the elite and average athlete have about the same amount of glycogen available for training. implying not only is power relative to FTP (or whatever measure you might use for aerobic capacity) important, but absolute power is as well. Consider an elite rider with an FTP around 400 W and a more average one with FTP=250 W. Riding at 70% of FTP, the elite rider will be burning around 60% more glycogen than the average one. Given the two riders have about the same amount available go glycogen available to them, the average rider will be able to sustain a higher percentage of FTP before exhausting their glycogen. Remember Seiler's 80/20 is merely an observation of how elite athletes train and as far as I know, he doesn't explain why. I believe they spend so much time at low intensities because they are glycogen limited. For those of us with lower FTPs, our glycogen stores allow us to train at higher intensities and as seen in Coggan's table below, get more stimulus for adaptation.