Critical Power: Implications for Determination of VO2max and Exercise Tolerance
Key Findings (concepts)
The power-duration relationship (abstract):
For high-intensity exercise, time to exhaustion (t) rises as a predictable, hyperbolic function of decreasing power (P) or velocity (V). Two parameters describe it: the critical power (CP, or critical velocity CV) — the asymptote — and the curvature constant W', such that t = W'/(P − CP).
The relationship is highly conserved across species and across modes of exercise.
Critical Power (CP):
The highest rate of energy transduction (oxidative ATP production, VO2) that can be sustained without continuously drawing on the energy store W'.
The paper presents CP as a practical framework for studying fatigue mechanisms and the plasticity of exercise performance; it also reviews alternative mathematical models of the relationship.
Not from this paper: how CP relates to FTP and the second threshold is covered in Iannetta 2020 REF-038.
W' (W-prime):
A finite energy store, composed in part of anaerobic energy sources, expressed in kilojoules; the limit of tolerance is reached when W' is depleted.
Not from this paper: the time course of W' reconstitution is in Chorley 2022 REF-131.
Intensity domains (full text; not checked against the abstract): the review frames exercise in moderate, heavy and severe domains, with CP as the boundary above which VO2 and metabolites do not stabilise and exhaustion arrives when W' runs out.
Practical Application
The paper's model, not a trial result: above critical power, time to exhaustion follows t = W'/(P − CP) — CP is the highest rate of oxidative energy production that can be held without continuously spending the finite store W' (kJ), and the task ends when W' is depleted. For an athlete this means sustained efforts belong below CP; every second above CP spends a fixed budget that no pacing trick enlarges within the effort.
Inference, not tested here: efforts meant to drive VO2 toward VO2max have to sit above CP, because below CP VO2 stabilises; how long such an effort can last is set by W' and how far above CP the power is.
Limitations
A narrative review of the CP concept: it carries the model and its evidence base, not new participants or new numbers. Any specific value (kJ of W', typical durations per domain) has to come from the empirical entries it points to.
A brief narrative review by the authors of the CP model; the mechanistic claims summarise laboratory studies, mostly in recreationally active to trained adults.
What CP does NOT claim — a fixed sustainable duration — is set out in the same group’s 2026 update (REF-751).
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A: narrative review from the leading CP group, no systematic method, no meta-analysis
Content correction 2026-09-27
"Heavy domain 40-240 min" and "W' typically 15-25 kJ in trained cyclists" -> not in the abstract; removed.
"CP > FTP in most cases" and "bi-exponential reconstitution" -> claims of other papers; kept only as pointers to REF-038 / REF-131 marked "Not from this paper".
House plan items ("5-hour event pacing", "weeks 9-10", "CP test weeks 4.5 and 8.5") -> not from the paper; removed. Lead bullet now states the paper's model.
Type "Foundational review, Level A" -> narrative review; regraded to B+ per KB-LEVEL-RUBRIC.