If you've been training with power or pace for any length of time, you've probably anchored your workouts to a single number: FTP on the bike, threshold pace on the run. It's simple. It's testable. And for a long time, it worked well enough.
But here's the thing: well enough isn't the same as well understood.
FTP and threshold pace were never wrong. They were incomplete proxies—single-point approximations forced to stand in for many different physiological realities. And that distinction matters more than most athletes realize.
The Quiet Limitation of Single-Point Metrics
Let's start with context, not critique.
Endurance training has always needed three things:
- A repeatable anchor for intensity
- Something individualized
- Something that could scale across workouts
FTP and threshold pace emerged because they delivered on those needs in a low-data era. They gave coaches and athletes a common language. A way to prescribe work. A benchmark to chase.
The problem? They were always derived from one duration—typically 20 minutes for FTP, 30–60 minutes for threshold pace—and then extrapolated across every other intensity.
That works fine when training stress is low and margins are wide. But the closer your decisions get to the edge of adaptation, the more costly approximation becomes.
Where Approximation Starts to Break
Here's where things get interesting—and where QT2.0 thinking sharpens the blade.
The issue with FTP and threshold pace isn't accuracy. It's decision quality.
Approximation breaks down when:
- Two athletes share the same FTP but perform very differently at 3, 8, 20, or 60 minutes
- Prescriptions feel "right" some days and wildly off on others
- Durability declines aren't visible until it's too late
- Coaches argue about zones instead of outcomes
You've probably felt this. A workout prescribed at "95% of FTP" that should feel controlled but leaves you cooked. Or a tempo session that feels easier than it should, even though the numbers say you're on target.
That's not a failure of effort. It's a failure of the model.
The closer your decisions get to the edge of adaptation, the more costly approximation becomes.
FTP works fine when training stress is manageable. It fails quietly when training stress matters most—during build phases, race prep, or when you're trying to thread the needle between stimulus and overreach. (We explore this tension in depth in Survivable Work vs. Stable Training.)
The Shift: From Single Point to Performance Model
This is where Critical Power (CP) and Critical Speed (CS) change the conversation.
Instead of anchoring everything to one test at one duration, CP and CS are built from multiple maximal efforts across different time domains—typically 3, 8, and 20 minutes, though protocols vary.
What you get isn't just a number. It's a mathematical performance model that describes the relationship between intensity and duration across your entire power or pace curve.
In plain terms:
- CP / CS = the highest output you can theoretically sustain without a predictable failure time
- W′ / D′ (W-prime / D-prime) = the finite "battery" you burn through when working above that line
Instead of guessing where "threshold" lives, you model the entire curve.
This is the shift from estimating fitness to understanding performance structure. If you're wondering whether FTP still has a place in modern training, we tackle that question directly in Is FTP Dead?
Why This Changes Coaching Decisions
Here's where QT2.0 separates from generic "CP is better than FTP" content.
CP and CS don't matter because they're more precise. They matter because they change how decisions are made.
Prescription
Zones are anchored to physiological behavior, not labels. Tempo, threshold, and VO₂ work are no longer blurred into overlapping ranges. Two athletes at the same CP can—and should—receive different workouts, because their W′ or D′ capacity reveals different strengths and limiters. (Learn more about how we identify and train these critical intensities.)
Evaluation
Here's where the model becomes powerful: changes in CP and W′ reveal which physiological systems responded to your recent training.
For example:
- CP increases, W′ decreases → Your aerobic system improved more than your top-end power. The training block built sustainable capacity.
- CP holds steady, W′ increases → You gained anaerobic capacity without shifting your threshold. High-intensity work paid off.
- Both CP and W′ increase → Broad-spectrum fitness gain across systems.
- Both decline → You're carrying fatigue, or the training stimulus wasn't sufficient.
This isn't about "good" or "bad." It's about understanding whether your training delivered the intended adaptation. If you programmed a base-building block and see CP rise with W′ drop, that may very well serve as confirmation that steady-state training moves the needle on your aerobic ceiling, but results in limited top-end adaptability.
With FTP alone, you'd only see a single number move—or not—and be left wondering why.
Progression
Because you understand how fitness is changing, you can make better decisions about what comes next.
Training stress can be applied right up to the adaptive edge without guessing. You can decide when to:
- Push → Both metrics trending up, systems are responding
- Hold → One system improving while the other stabilizes
- Absorb → Metrics flattening or declining, time to consolidate gains
This is based on what the athlete can actually support right now, not what a zone chart says they should be able to do. This concept of matching training to your current physiological state and adaptive opportunity is central to how QT2.0 works.
CP and CS don't tell you what to do. They tell you what the athlete can actually support right now.
That distinction is foundational to QT2.0.
CP / CS as Pillar 1 (Not the Whole System)
Here's the subtle but critical point: we are not positioning CP and CS as the answer. We're positioning them as the entry point.
At QT2, we use CP and CS as:
- The stable anchor for intensity prescription
- The common language across bike and run
- The baseline for StressLogic, durability tracking, block design, and decision-making under load
But CP and CS alone don't manage fatigue. They don't choose weekly TSS. They don't account for life stress, mindset, sleep quality, or injury risk.
That's why QT2.0 exists beyond the metric.
CP and CS give you the map. QT2.0 teaches you how—and when—to move.
What This Means for You
If you've been training with FTP or threshold pace and it's working, keep going. Seriously. There's no need to overcomplicate what's already producing results.
But if you've hit a point where:
- Workouts feel inconsistent even when the numbers match
- You're not sure if you're adapting or just accumulating fatigue
- You want to train closer to your edge without crossing it
- You're ready to move from guessing to understanding
Then CP and CS—and the system built around them—might be exactly what you need.
Not because they're more accurate. But because they change the quality of every decision you make.
And in endurance training, decision quality is everything.
Ready to experience training built on understanding, not guesswork? Explore our QT2 Base+ Training Program or work directly with our team through QT2.0 1-1 Triathlon Coaching. Whether you're looking for structured programming or fully individualized coaching, we'll help you train smarter—right where it moves the needle.
