What is Functional Threshold Power?
Functional Threshold Power (FTP) represents the highest average power output, measured in watts, that a cyclist can sustain for approximately one hour. It was developed and popularized by Dr. Andrew Coggan and Hunter Allen in their book Training and Racing with a Power Meter.
FTP is a field-based proxy for your lactate threshold — the intensity where lactate production begins to exceed your body's ability to clear it. Below FTP, effort is aerobically sustainable. Above FTP, fatigue accumulates rapidly and forces you to slow down within minutes.
The standard test protocol is a 20-minute all-out effort multiplied by 0.95 to estimate the one-hour value. FTP is the foundation of the entire power-based training system: it sets your seven Coggan power zones, drives every Training Stress Score (TSS) calculation, and underpins the Performance Management Chart (CTL, ATL, TSB). If your FTP is wrong, every downstream metric is unreliable.