# Critical power

Critical power (CP) is your aerobic 'ceiling'. It is the highest power output (or running speed, called critical velocity) you can sustain without fatiguing out. Just below CP, your body can keep refilling a finite energy reserve (called W'). Just above it, that reserve (W') drains toward exhaustion. CP and W' are estimated from the curved relationship between power and time-to-exhaustion across several all-out efforts. CP lands close to two other markers: the maximal lactate steady state and the respiratory compensation point. It marks the boundary between 'heavy' and 'severe' exercise. CP falls with age, and it predicts endurance performance and cardiovascular risk. Training that pushes your CP higher raises the level of effort you can sustain.

## Sources

- Jones AM, Vanhatalo A, Burnley M, Morton RH, Poole DC. (2010). Critical power: implications for determination of VO2max and exercise tolerance. Medicine and Science in Sports and Exercise. https://doi.org/10.1249/MSS.0b013e3181d9cf7f

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_Canonical: https://longevity-switzerland.com/en/glossary/critical-power · Part of Longevity Cities · Updated 2026-06-22_