Learn more about our concepts and calculations
Critical Power Matters
For the Adaptive W′ & Endurance Tracker to be accurate, having a reliable Critical Power (CP) value is essential. CP defines the boundary between sustainable effort and intensity that rapidly drains your limited energy reserves. When CP is accurate, fatigue, lactate accumulation, and bonk risk can be modeled realistically. When it isn’t, predictions become misleading.
What Is Critical Power (CP) and W′?
Critical Power represents the highest power you can sustain aerobically without fatigue accelerating out of control. Efforts above CP draw from a finite energy reserve known as W′ (Watt Prime) — essentially the “matches” you burn during hard efforts. Once W′ is depleted, performance drops sharply.
Domestique's Adaptive W′ & Endurance Tracker uses CP and W′ as the physiological foundation for its real-time predictions, making accurate inputs critical.
CP and W′ are not guessed — they are calculated from true maximal efforts, particularly short, high-intensity efforts that define how your body responds under stress. That’s why structured testing is important.
Our Recommended Testing Protocol
We recommend the following protocol to obtain reliable 2- and 5-minute maximal power values:
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Warm up: 15 minutes
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3 × 1 minute at 110 RPM, 1 minute easy between efforts
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5 minutes easy
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2 minutes all out
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30 minutes easy
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5 minutes all out
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Cooldown
These efforts should be truly maximal. You only need to perform this test occasionally — typically when fitness changes meaningfully.