FTP

Definition

Functional Threshold Power — FTP — is the highest power output an athlete can sustain in a quasi-steady state for approximately one hour. Expressed in watts. Coined by Andrew Coggan for cycling but increasingly used in running through the new generation of running power meters (Stryd, Garmin, COROS, Polar).

FTP is conceptually the power-meter analog of AnT. Physiologically, the two boundaries describe the same territory — the sustainable ceiling of aerobic-dominant work — with power and heart rate as two different ways to measure it.

Why it matters to runners

Power-based training offers advantages heart rate cannot match on certain terrain: it responds instantly (no HR lag), it is unaffected by heat or hydration, and it gives a clean reading on hilly or trail courses where pace becomes unreliable. A 6:00 /km running pace uphill produces more power than the same pace on flat ground; a power meter sees the difference, and a pace-based plan does not.

FTP's limitation is the same as VDOT's and HR's — it is a single number describing a complex physiology. Different athletes reach the same FTP through different underlying proportions of VO2max, lactate-buffering capacity, and economy. For training prescription, FTP is most useful as a zone anchor; for cross-athlete comparison, it is most useful alongside body weight (watts per kilogram).

Your Pacer does not require a running power meter. Users who own one benefit from zone definitions that integrate with FTP — Z1 below 80% FTP, Z2 at 80 to 94%, Z3 at 95 to 105%, and so on — as a parallel reading to the HR-anchored zones.

How it's measured

• 60-minute time trial — the original definition. All-out effort held for one hour. Physically demanding; rarely used in practice.
• 20-minute test × 0.95 — the common field-test proxy. A 20-minute all-out effort; FTP is estimated at 95% of the average power.
• Ramp test — incremental-load test that estimates FTP from the peak one-minute power at exhaustion.
• Critical power (CP) analysis — deriving FTP-equivalent values from the power-duration curve across multiple test distances.

Like VO2max and AnT, FTP is a moving target. It is re-evaluated every 4 to 8 weeks if training is progressing, or after any significant change in fitness or body composition.

Related terms

• AnT — the HR-anchored equivalent of FTP.
• Intensity Zones — power-based zones parallel HR-based zones.
• Quality Session — threshold intervals can be prescribed at % FTP.
• Training Load — TSS (Training Stress Score) is computed from power relative to FTP.

Further reading

• Coggan & Allen, Training and Racing with a Power Meter (3rd edition). The canonical FTP formulation.
• Friel, The Power Meter Handbook. Practical application for endurance athletes.
• Jones & Vanhatalo, The "Critical Power" Concept, Sports Medicine (2017). The CP framework that refines FTP.