We have seen that bFTP (Bike Functional Threshold Power) is the power output at the Functional Threshold, or better said, the maximum power output theoretically possible for an athlete during an hour of cycling. We have also seen that most cycling computers have software that can help an athlete to determine with relative accuracy their own bFTP value. These same instruments can also determine the values of the Aerobic Threshold and of the Anaerobic Threshold.

Over the past years, based on the bFTP, the AT2 values (Aerobic Threshold) and AT4 values (Anaerobic Threshold), the intensity zones have been refined, both numeric and metabolic. As such, they are very useful in setting up the training programs. 

Dr, Andrew Coggan developed the Power Zones (Z) as outlined in Tab n°1

I would like to stress that these zones are indicative and open for interpretation. The zones are not clearly separated and are not rigid parameters. As an athlete and a trainer of champions I have found that these values are variable and susceptible to frequent errors because of faulty identification of the objectives. Every zone has analogies and similarities with the adjacent zones.  A correct balance between intensity and volume of training will heighten the bFTP with all the benefits for the performance.