Originally Posted by
jrobe
What you need to know for training purposes is your power output in real time. Your average power output for a given length of time may be interesting but it is useless.
If you have a powermeter than tells you your instanenous power output in real time, you can determine your training zones based on power. Then you plan a training program based on these zones. For example, today workout will be three 10 minute intervals at zone 4 or maybe 280 watts (ie. you watch your powermeter and put out 280 watts for the 10 min interval), etc, etc, etc..
I'd argue for the opposite as it's hard to nail it to 280W+/- 10W even under perfect conditions. It's the normalized power of the duration of the interval that matters. After all, by standard definition, you average power of a 60min long time trial is FTP, the power you use to determine all your training zones.