What FTP is
Functional Threshold Power (FTP) is the highest average power, in watts, a cyclist can sustain for roughly one hour. Andrew Coggan introduced it as a practical proxy for the lactate threshold and maximal lactate steady state, the ceiling above which fatigue accelerates sharply. It anchors every Coggan power zone.
Because power is measured directly at the pedals or crank, FTP is more repeatable than heart rate: it doesn't drift with heat, caffeine or fatigue. A 10-watt error shifts every zone, so an accurate, current number matters more than any clever workout built on it.
The Coggan seven-zone model
Each zone is a percentage of FTP. Zone 1 Active Recovery is below 55%, Zone 2 Endurance is 56–75%, Zone 3 Tempo is 76–90%, and Zone 4 Threshold is 91–105%, the band straddling FTP itself. Above that, Zone 5 VO₂max is 106–120%, Zone 6 Anaerobic Capacity is 121–150%, and Zone 7 Neuromuscular Power is everything above 150%.
Most endurance volume sits in Zones 1–2; hard adaptations come from short, targeted time in Zones 4–6. The top three zones are duration-limited: you hold Zone 5 for a few minutes and Zone 7 for seconds, so they're prescribed as intervals, not steady efforts.
What is Sweet Spot?
Sweet Spot is the band from 88% to 94% of FTP, between Tempo (Z3) and Threshold (Z4). At an FTP of 250 W that is 220–235 W. It delivers a near-threshold stimulus for noticeably less fatigue than riding at FTP, which is why time-crunched riders use it to build sustainable power efficiently.
Sweet Spot isn't a formal Coggan zone but a practical sub-band carved from the upper Tempo / lower Threshold range. Typical sessions are 2–4 intervals of 8–20 minutes, totaling 30–60 minutes of work without the recovery cost of full threshold sessions.
How is FTP measured?
The reference field test is a 20-minute maximal time trial: FTP is 95% of the 20-minute average power, the 5% haircut accounting for 20 minutes being shorter than an hour. An 8-minute protocol takes 90% of the average of two 8-minute efforts, and a ramp test estimates FTP as roughly 75% of the one-minute peak power (MAP) reached before exhaustion.
Each method gives a slightly different number, so pick one and stick with it to track change consistently. Re-test every 4–6 weeks during focused training; a stale FTP makes every derived zone wrong.
FTP vs threshold heart rate
FTP and lactate-threshold heart rate (LTHR) measure the same boundary from two angles: FTP is the power at threshold, LTHR the heart rate. Power responds instantly, while heart rate lags effort by 1–3 minutes and drifts upward in heat or fatigue, so power is the better controller for short, hard intervals.
The two are complementary, not redundant. A rising heart rate at the same power flags fatigue or dehydration; power that falls at the same heart rate over a long ride reveals cardiac drift. Many cyclists set zones by FTP and cross-check with LTHR.
The 20-minute FTP field test
The 20-minute test is the most widely used FTP protocol. Do it rested, on a trainer or flat road, and pace it like a hard, even time trial, not a sprint start.
- 1
Warm up thoroughly
20–30 minutes of easy riding with a few short, rising spin-ups to open the legs and lungs.
- 2
Blow off the top end
Ride a 5-minute all-out effort to flatten your anaerobic contribution, then spin easy for about 10 minutes.
- 3
Ride a 20-minute time trial
Hold the highest steady power you can for a full 20 minutes, evenly paced, no fade. Record the average power.
- 4
Take 95% of the average
FTP is 95% of that 20-minute average. Enter the 20-minute number and choose the 20-min mode to apply the factor automatically.
Worked example
For a cyclist with an FTP of 250 W:
| Zone 2, Endurance (56–75%) | 140–188 W |
| Zone 3, Tempo (76–90%) | 190–225 W |
| Zone 4, Threshold (91–105%) | 228–263 W |
| Sweet Spot (88–94%) | 220–235 W |
From a 20-minute test, this rider would have averaged about 263 W (250 ÷ 0.95) for the 20 minutes.
Frequently asked questions
What is a good FTP?
FTP only means something relative to body weight, in watts per kilogram. A recreational cyclist sits near 2.5–3.0 W/kg, a strong amateur around 3.5–4.0, and elite road professionals exceed 5.5 W/kg at threshold. Raw watts say little until you divide by your mass.
How do I test my FTP?
The standard field test is a 20-minute maximal time trial after a full warm-up and a 5-minute blow-off effort. FTP is 95% of the 20-minute average power. Alternatives include an 8-minute protocol (90% of average) and a ramp test (about 75% of one-minute peak power).
What is Sweet Spot training?
Sweet Spot is riding at 88–94% of FTP, between Tempo and Threshold. At 250 W FTP that is 220–235 W. It gives a threshold-like stimulus for less fatigue than full FTP work, making it efficient for building sustainable power in limited training time.
How often should I re-test FTP?
Every 4–6 weeks during focused training, or whenever your fitness changes noticeably. FTP rises with training and falls with detraining, and an out-of-date number throws off every derived zone. Always re-test with the same protocol so numbers stay comparable.
Is FTP the same as critical power?
Close cousins, not identical. FTP estimates the power sustainable for about an hour from a single test, while critical power is the asymptote of the power–duration curve, derived from two efforts and paired with W′. Critical power usually lands within a few percent of FTP.
Sources
- Allen, Coggan & McGregor, Training and Racing with a Power Meter. 3rd ed. (2019). Definition of Functional Threshold Power and the seven-zone power model.
- Allen & Coggan, FTP & Sweet Spot. Definition of Sweet Spot (88–94% FTP) and the 20-min / 8-min / ramp estimation factors.