The Functional Threshold Power is the highest average power one can sustain during a continuous 60-minute test on a bicycle. To get an accurate FTP measurement, one must normally take part in a 60-minute long very difficult test (that will leave him/her in a state of total exhaustion). Hence, a high level of motivation goes without saying.
The test requires an equipment that measures the real-time and average pedalling power output (pedals, crank or rear hub equipped with a power meter) or a smart home-trainer.
The 20-minute version
Since a 60-minute test is extremely demanding (and very difficult to do on the road), we can resort to a 20-minute version. We know that cyclists can generally sustain (on a 20-minute test) an average power that is 5 % higher than on a 60-minute test. So, for example, if one averages a power of 200 watts on a 20-minute test, his/her actual FTP is 190 watts (200 – 5 % = 190).
Those who particularly excel in short distance races, and show less endurance than cyclists of similar performance level, should even substract 10 % to the 20-minute result, instead of only 5 %.
Before the test, a good warm up is a must : 20 minutes at a confortable pace, spiced with a few higher intensity spikes, followed by a long recovery period.