Since my new bike trainer records power I decided to use power as a guide trough winter training. Power is considered superior to heart rate due to HR day-to-day variations and slow response to change in intensity. So, in order to determine training zones I had to find my Functional Threshold Power (FTP) which is average power that could be sustained for one hour. I wasn’t eager in riding hard for one hour in this part of season so I decided to use 20 minute protocol that could predict FTP. This protocol makes you ride as hard as you can for 20 minutes and you have to keep intensity constant trough interval (no fading). When you subtract 5% from average 20-minute power you get an estimate of FTP. FTP can vary from 92 to 98% of 20 minute power so this is an estimate.
I managed a good guess of my initial effort and I was able to hold almost the same power numbers throughout the test. Average 20 minutes power was 328W, which translates into FTP of 312W. This doesn’t sound too bad for this part of the season. We’ll see how this numbers translate on the road in the spring.