Power and FTP

Power measured in watts is the external mechanical output, captured by a cycling power meter, a smart trainer, a rower's monitor, or a running power device. Unlike pace (confounded by terrain/wind) and HR (laggy and drifting), power is immediate and terrain-immune, making it the gold-standard intensity signal where a meter is available.

FTP (Functional Threshold Power) is the highest power roughly sustainable for ~1 hour — a practical proxy for the lactate/critical-power threshold (see critical-power-ftp). It is the anchor for power zones, just as HRmax anchors HR zones. FTP is commonly estimated from a 20-minute test (≈ 95% of 20-min average power) or a ramp test.

Derived power metrics worth logging:

• Power zones → power-based time-in-zone, which avoids HR lag on intervals.
• Normalized Power (NP) — a weighting that reflects the metabolic cost of variable efforts better than simple average power.
• W/kg — power-to-weight, the key comparison metric for climbing and racing.
• Trending FTP over a block is a primary endurance KPI (see kpis-endurance); rising power at equal HR is a clean efficiency gain (see cardio-efficiency).

• Power (watts) = external output; immediate and terrain-immune.
• FTP ≈ max power sustainable ~1 hour; anchors power zones.
• FTP often estimated as ≈95% of a 20-min test average.
• Power zones enable lag-free interval time-in-zone.
• W/kg, Normalized Power, and FTP trend are the key derived metrics.

• critical-power-ftp — the physiology behind FTP/critical power.
• time-in-zone — power zones feed cleaner TIZ.
• cardio-pace — power is the terrain-immune alternative to pace.
• cardio-efficiency — power-at-equal-HR as a fitness signal.
• kpis-endurance — FTP and W/kg are headline endurance KPIs.