The Critical Power (CP) Model: A Framework with More Explanatory Power than FTP

Starting with a Stuck Athlete

I remember this vividly. A few years ago, an amateur rider working in the Hsinchu Science Park came to me—let’s call him A-Jhe. He was diligent, having run the 20-minute FTP test on Zwift several times, pushing his numbers from 245W up to 272W. On paper, his progress looked impressive. But he grew more frustrated with each session, because every time he hit a steep, short climb on Yangjin P-Style Mountain or Fengguizui, he blew up completely and couldn’t recover for what followed. Conversely, on long, gradual climbs, he actually lasted longer than anyone in his group.

He asked me: “Coach, my FTP is clearly higher than my teammates’, so why do I die every time someone throws in a surge attack?”

This question can never be answered with a single FTP number. Because FTP only tells you “roughly how hard you can sustain effort,” but it tells you nothing about “how much reserve you have above that line, and how quickly you recover once it’s depleted.” Beneath the same FTP number, there could be two riders with wildly different characteristics: one who can attack repeatedly but not for long, and another who’s steady as a rock but lacks any explosive power. FTP lumps them together as equals, which is clearly unreasonable. And that’s exactly the piece of the puzzle the Critical Power (CP) model fills in. In this article, I want to walk you through how I’ve used the CP concept with my athletes, the testing methods, and how to design interval workouts with it—complete and in full.

Conceptual Foundation: Power Isn’t a Single Number, It’s a Curve

The Power–Duration Relationship

Let’s start with the most core intuition: the power you can output is tied to how long you need to sustain it.

If you go all-out for 5 seconds, you can produce an absurd number of watts. Push for 1 minute, and it drops significantly. Hold it for 20 minutes, and it’s lower still. Stretch it to a full hour, and it drops even more. Plot these “maximum average powers for different durations” on a chart, and you get a curve that bends downward to the right, then gradually flattens out. That curve is the power–duration relationship.

What the Critical Power model does is describe this curve with a concise mathematical formula. It condenses the entire curve into two parameters:

• CP (Critical Power, in watts): The horizontal asymptote where the curve finally flattens out. Think of it as the ceiling of your “sustainable aerobic engine.”
• W’ (read as W-prime, pronounced “W-prime,” in joules): The area above CP on the curve, representing the “one-time finite work” you can do above CP.

W’ Is Your Battery

The analogy I use most with my athletes is: CP is the sustained output of your engine; W’ is the battery you carry that depletes but recharges.

This analogy works because it’s directly calculable. Since 1 watt equals 1 joule per second:

If your CP is 300W and your W’ is 20,000 joules, then when you ride at 400W, you’re using 100W above CP. W’ ÷ excess power = 20,000 ÷ 100 = 200 seconds. In theory, you can hold 400W for about 200 seconds before the battery hits empty and you’re forced to slow down.

With the same 20,000-joule battery, if you only exceed by 50W (riding at 350W), you can last 400 seconds; if you really push and exceed by 200W (riding at 500W), you’ll only last 100 seconds. This is why the CP model explains A-Jhe’s predicament—his CP was decent, but his W’ was on the small side, so when faced with repeated short surges, his battery drained quickly.

Why CP Has More Explanatory Power Than FTP

Let me clarify the relationship between CP and FTP here, because many people mistakenly think they’re the same thing.

According to mainstream sports physiology, FTP is essentially a performance-derived practical construct, roughly corresponding to the “maximal lactate steady state” (MLSS)—the highest intensity at which blood lactate production and clearance reach equilibrium. CP, on the other hand, is a physiological boundary calculated from a mathematical model, marking the line between the “heavy” and “severe” exercise intensity domains (TrainingPeaks, PMC review).

The significance of this line is critical:

• Below CP: Physiological markers (oxygen uptake, blood lactate) can stabilize, allowing you to sustain effort for a long time with slow fatigue accumulation.
• Above CP: Fatigue accumulates rapidly in a predictable manner, and the moment W’ is depleted, you can no longer continue.

In other words, CP doesn’t just give you a “line”—it also comes with W’, the information about “how much reserve you have above that line.” FTP gives you only one number; the CP model gives you two parameters, doubling the information content. That’s the fundamental reason it has “more explanatory power.”

The table below summarizes the differences:

Aspect	FTP (Functional Threshold Power)	CP + W’ (Critical Power Model)
Nature	Performance-oriented single value	Two parameters from a mathematical model
Physiological correspondence	Roughly corresponds to MLSS	CP marks the heavy/severe domain boundary
Information content	One number (intensity ceiling)	CP (engine) + W’ (battery capacity)
Can it explain short-surge tolerance	No	Yes, directly calculated via W’
Common tests	20 min × 0.95 or 60 min	3-minute all-out test or multi-stage tests
Guidance for intervals	Weak, only sets zones	Strong, can calculate recovery and recharge

One thing to note: for many people, CP tends to be slightly higher than FTP measured from a 20-minute test, and the metabolic responses at various intensities aren’t identical either. So don’t try to force the two numbers together. They’re two different languages.

Practical Methods: How to Measure Your CP and W’

With the concepts covered, let’s get to what everyone cares about most: how do you actually measure them? In coaching my athletes, I primarily use two methods.

Method 1: 3-Minute All-Out Test (3MAOT)

This test protocol was proposed by Vanhatalo et al. in 2007. The core concept is clever: as long as you pedal all-out, the W’ battery will be depleted within about 150 seconds; once the battery is empty, the power you can still sustain equals CP.

Research has observed that in a 3-minute all-out test, power drops to a stable level within about 135 seconds, and CP is taken as the average power of the final 30 seconds; W’ is the total work done above CP during the entire test (PubMed, Medium explanation).

Its biggest advantage is that one test gives you both CP and W’ simultaneously, saving time. But that’s also where the cruelty lies—you must go “truly all-out” from the very first second; no pacing, no holding back. This is a huge mental challenge.

3-Minute All-Out Test Procedure:

1. Warm up thoroughly: At least 15 to 20 minutes, including 2 to 3 high-cadence sprints of 10 to 15 seconds each to wake up the legs.
2. Set a fixed resistance: If using a smart trainer, make sure to switch to linear/slope mode (not ERG mode), because ERG locks the power and you won’t be able to produce your true explosive output.
3. Go all-out from the first second: Don’t hold back, don’t pace. Mentally treat it as “these 3 minutes are everything.”
4. Never give up: Even if your power drops very low and it’s extremely painful in the second half, keep pedaling all-out until the 3 minutes are up, because the final 30 seconds are critical for calculating CP.
5. Extract the data: Average power of the final 30 seconds = CP; the integral of work above CP over the entire test = W’.

I usually warn my athletes beforehand: you’ll feel like throwing up after this test. Rest fully for 48 hours before doing it, and it’s best to have someone nearby to call out the time and cheer you on.

Method 2: Multiple Time-Trial Protocol (CP3/12 or More Intervals)

Another more “classic” approach is to perform several all-out tests of different durations separately, then use math to solve for CP and W’. A common setup is a 3-minute and a 12-minute effort (some coaches add shorter or longer intervals), done on different days, or on the same day with sufficient rest in between.

The logic is: each all-out effort is “using up part of W’, plus the amount sustained by CP.” With data from two or more efforts, you can separate CP (the asymptote of the slope) and W’ (the intercept).

The advantage of this method is that the numbers are usually more stable and reliable (especially for well-trained riders, a single 3-minute all-out test can sometimes give a biased W’ estimate); the downside is that it requires multiple efforts, which is time-consuming and painful.

The table below compares the two testing methods so you can choose based on your situation:

Test Method	Number of Efforts	Parameters from One Session	Advantages	Best Suited For
3-Minute All-Out (3MAOT)	1 effort	Both CP + W’	Time-efficient, done in one go	Those short on time, want quick values
3+12 Minute Two-Stage	2 efforts (can be on separate days)	CP + W’ derived from calculation	More stable numbers, higher reliability	Intermediate to advanced, seeking precision
Multi-Stage (adding 5 min/20 min, etc.)	3+ efforts	Most complete curve	Minimal error	Competitive athletes, coach verification

Practical Tips for the Taiwan Context

When testing CP in Taiwan, I specifically emphasize a few things:

• Avoid the humid midday heat: Taiwan’s summer afternoons are hot and humid, with perceived temperatures often above 33°C. Outdoor CP testing is not only dangerous, but the data will also be dragged down by heat stress. I recommend early morning or evening, or simply test indoors on a trainer in an air-conditioned room with a fan.
• Use a powerful fan indoors: Indoor riding has poor heat dissipation. A large fan can significantly reduce heart rate drift and give you cleaner data.
• Venue selection: If doing multi-stage testing outdoors, riverside bike paths (such as along the Xindian River or Dajia River) with flat, traffic-light-free sections are suitable for longer efforts; for shorter efforts, a steady, gentle climb (such as the early section of Fengguizui) also works.
• Hydrate and replenish salt before testing: Taiwan’s humidity causes heavy sweating. From the day before through the test day, make sure to fully replenish fluids and electrolytes—dehydration will distort both your performance and the data.

Designing Interval Training with CP and W’

This is where the CP model truly shines. With CP and W’, interval workouts are no longer set by feel—you can use battery logic to calculate “how long to push, how long to rest.”

Core Logic: Discharge and Recharge

Remember two things:

1. Riding above CP = discharging (depleting W’). The discharge rate depends on how far above CP you are.
2. Riding below CP or resting = recharging (W’ replenishing). The recharge rate depends on how far below CP you drop; the easier you rest, the faster it recharges.

So designing intervals is essentially arranging the rhythm of “discharge periods” and “recharge periods,” allowing you to complete more high-intensity work in total than continuous riding. Note that W’ recharge is neither linear nor instantaneous—if you don’t rest enough and W’ isn’t fully topped up, the next effort will hit empty sooner.

A Concrete Calculation Example

Using the data A-Zhe later measured as a demonstration: CP = 290 watts, W’ = 18,000 joules.

Suppose I want him to do intervals that consume about one-third of W’ per effort (about 6,000 joules), with the sprint power set at 370 watts (80 watts above CP):

• Time per effort = 6,000 ÷ 80 = 75 seconds
• Each effort uses about one-third of the battery; theoretically, three efforts with no rest would hit empty exactly, so rest must be scheduled in between to allow recharging

With this calculation, the workout goes from “roughly push for a bit over a minute” to a well-founded “370 watts × 75 seconds.” That’s the precision the CP model brings.

Three Ready-to-Use Interval Workouts

The three workouts below are templates I commonly give to athletes with different goals. Adjust the power based on your own CP/W’ values.

Workout Name	Goal	Content	Intensity Setting Principle
Micro-Intervals (Recharge Practice)	Raise CP, extend W’ tolerance	40s (CP+15%) / 20s (CP-40%), 13 reps per set, 2 to 3 sets	Short discharge, short recharge, very large total volume
Classic VO2max	Improve aerobic ceiling, raise CP	3 to 5 min (CP+8~12%) / equal time easy riding, 4 to 5 reps	Each rep approaches but doesn’t fully deplete W’
Repeated W’ Depletion	Train “bigger battery” and pain tolerance	All-out until power drops (about 60~90s) / rest 5 to 8 min, 4 to 6 reps	Fully drain W’ each rep, fully recharge before the next

The cleverness of micro-intervals lies in this: the 40-second discharge and the 20-second “relative rest” still involve pedaling (just dropping below CP to recharge). Because each rep consumes little and recharging is ongoing, you can accumulate a very large volume of high-intensity work, which is particularly effective for raising CP.

The key to the VO2max workout is that each rep should “approach depletion but not completely blow up.” If you use up all of W’ on the first rep and collapse on the second, the intensity is set too high and needs to be adjusted downward.

Repeated W’ depletion deliberately drains the battery to empty on every rep. This workout is very hard—at most once a week—and its main purpose is to train W’ capacity and your tolerance for deep fatigue.

Real-Time W’ Balance: The Dashboard During a Race

More advanced platforms (some bike computers, training software) will estimate your current “W’ balance” in real time, just like a fuel gauge, letting you see how much battery remains during a race. This is extremely useful in practice.

Take the Wuling example: the entire long climb is mostly around or below CP, a “slow charging” pace; but the decisive moments are often a few steep sections or the final sprint, where you’ll discharge rapidly. If you know how to read W’ balance, you can deliberately ease off slightly before a steep section to let the battery recharge, saving your bullets for where they’re truly needed, rather than burning through W’ halfway and struggling at a crawl afterward.

I often tell athletes targeting a specific event: A race isn’t about who discharges the hardest, but who spends their W’ in the right places. This is precisely where the CP model offers its most practical tactical value over FTP—FTP only tells you “don’t exceed this power for too long,” while CP plus W’ balance tells you “how much you can exceed it right now, for how long, and when to back off.”

One caveat: the W’ balance recharge model is an estimate, and different software uses different algorithms. Don’t treat the numbers as absolutely precise, but they work great as a “dashboard for relative trends.”

The Relationship Between Fueling, Recovery, and CP

Many people think CP and W’ are only about “leg strength,” but energy intake plays a critical role behind the scenes, especially for longer rides.

Carbohydrates Are the Fuel for High Intensity

In the severe zone above CP, your body relies heavily on carbohydrates for energy. If your glycogen stores run dry, forget about W’ discharge—even CP will be forced downward. This is the so-called “bonking.” So your fueling strategy during long rides (e.g., Wuling, one-day Taipei–Kaohsiung) directly affects whether you can hold CP in the later stages.

General principles (not a precise prescription; adjust based on body weight and intensity):

Ride Duration	Hourly Carbohydrate Intake Guideline	Local Taiwanese Approach
Under 1 hour	Usually no extra intake needed; focus on hydration	Plain water or diluted sports drink
1 to 2.5 hours	About 30 to 60 grams of carbs per hour	Energy bars, bananas, convenience store rice balls
Over 2.5 hours	Can push toward 60+ grams per hour, and watch sodium intake	Gels, electrolyte drinks, salty snacks

One big advantage for Taiwanese riders is the high density of fueling stops: even in mountainous areas, convenience stores are common, and their rice balls, bananas, Pocari Sweat, and salt candies are very convenient. But don’t just eat anything because it’s easy—food that’s too greasy or hard to digest during high-intensity riding can easily upset your stomach.

Hydration and Electrolytes in Humid, Hot Conditions

Taiwan is humid and hot, and a long ride produces a massive amount of sweat. Dehydration will simultaneously lower your CP performance, push your heart rate higher, and impair focus. A general recommendation is about 500 to 800 ml of water per hour (adjust based on body size, temperature, and sweat rate). When sweating heavily, you need to replace sodium as well to avoid hyponatremia and cramps. If you’re a “salty sweater” (with a white salt residue on your clothes after a ride), be even more proactive with electrolytes.

Recovery Determines Your Next CP

The long-term capacity of W’ and the continued improvement of CP are both built on recovery after training. Sleep, protein intake (to aid muscle repair), and not pushing every single session to the absolute limit are the foundations for steadily raising CP. I’ve seen too many athletes stuck at the same CP, and the problem isn’t that their training plan isn’t hard enough—it’s that recovery is insufficient. Training hard every day with poor sleep gives your body no chance to adapt.

Cross-Validating with Heart Rate and Rate of Perceived Exertion

Power numbers are objective, but don’t ignore the two free sensors on your body: heart rate and rate of perceived exertion (RPE).

• Heart rate (bpm): Riding near CP, heart rate is usually close to but not at maximum. If heart rate is unusually high at the same power, it could be a sign of fatigue, dehydration, heat stress, or poor sleep.
• Rate of perceived exertion (RPE): Rate yourself on a 0 to 10 scale. Near CP, it typically falls in the 7 to 8 range—“very breathless but can still hold on for a while.” Once you’re into W’ discharge, it quickly climbs to 9 or 10.

I teach athletes a practical habit: every time you do a CP-related workout, record power, heart rate, and RPE together. If one day the power target hasn’t changed, but heart rate is noticeably higher and RPE feels unusually hard, that’s often your body telling you, “I didn’t come in fully charged today.” That’s the time to lower intensity or rest, not to push through. This kind of cross-validation is more reliable than looking at any single number.

CP Model FAQ

Q1: I don’t have a power meter. Can I still use the CP model?

Strictly speaking, CP and W’ are defined in watts and joules, so without a power meter, precise quantification is difficult. But the concepts still apply—you can use the intuition of “sustainable pace” for CP and “short-burst tolerance” for W’ to structure your training. In the long run, if you want to take CP seriously, investing in a power meter is worthwhile.

Q2: My CP came out higher than my FTP. Did I do something wrong?

Not necessarily. As mentioned earlier, for many people CP will be slightly higher than an FTP measured from a 20-minute test, because the definitions and calculation methods differ. The key is to stay consistent within one system: if you set workouts with CP, keep using CP. Don’t mix CP one day and FTP the next with conversions—that will only create confusion.

Q3: How often should I retest CP?

Generally every 4 to 6 weeks, or when transitioning between training phases. Taiwan’s climate varies greatly, so I recommend testing once in the cool season and once in the hot season, because heat stress will significantly change your sustainable power.

Q4: Can W’ be trained to be larger?

Yes. Through repeated high-intensity short intervals (like the W’ repeated depletion workout mentioned earlier), both your W’ capacity and your tolerance for deep fatigue can improve. However, individual variation is large—don’t compare absolute values with others; just compare your progress against your own past.

Q5: Is the CP model suitable for complete beginners?

For those just starting out who haven’t built an aerobic base yet, I usually recommend accumulating easy miles first to build the engine, then moving on to CP testing and intervals. If you rush into CP tests and hard intervals without a solid base, you’re more likely to get injured or burn out.

Common Mistakes and Fixes

In all my years coaching athletes, the CP-related mistakes I’ve seen can almost all be grouped into the categories below. Check whether any apply to you.

Mistake 1: Pacing the 3-Minute Test

This is the most common and most critical error. Many people instinctively try to pace themselves when they hear “3 minutes,” holding back a little at the start. But the entire math of the 3MAOT relies on the assumption that you truly go all-out in the first segment, rapidly depleting W’. If you pace yourself, the power in the first segment isn’t high enough, W’ isn’t fully drained, and the power in the final 30 seconds will be overestimated, giving you an inflated CP.

Fix: Treat it like “a 3-minute time trial where the first part is all-out.” Before you start, take a deep breath and tell yourself there’s no holding back.

Mistake 2: Using ERG Mode for All-Out Tests

ERG mode on a smart trainer locks the target power—whether you pedal faster or slower, it delivers a fixed wattage. This is a disaster for an all-out effort test, because you simply can’t push beyond it.

Fix: For CP testing, always switch to slope/linear resistance mode, so the power is determined by your legs.

Mistake 3: Treating CP as a Permanent Number

CP and W’ change with training status, fatigue, and season. The CP you measured three months ago may no longer be accurate. Using old numbers to set workouts means the intensity won’t match up.

Fix: Retest every 4 to 6 weeks, or when transitioning between training phases. For Taiwan, I recommend scheduling retests in both the cool season (autumn/winter) and the hot season (midsummer), because heat stress significantly affects your sustainable power.

Mistake 4: Training Only CP, Not W’ (or Vice Versa)

A-Jhe’s original problem was only piling on long endurance miles (training CP) without any short-burst repeats (training W’), so his battery was both small and fragile. Conversely, some people only love short bursts, their CP never rises, and they fall off on long climbs.

Fix: Train both. Use the “micro-intervals/VO2max” from the earlier table to build CP, and use “W’ repeated depletion” to build battery capacity, adjusting the ratio based on your weakness.

Mistake 5: Ignoring That W’ Recharge Needs Enough Rest

Many people shorten their rest intervals based on feel, arbitrarily cutting them down. W’ recharge takes time; if you don’t rest enough, the next repeat bottoms out early, the quality of the entire session collapses, and you’re more prone to injury.

Fix: If you notice power dropping noticeably in the later repeats, or a severe loss of speed, it’s usually insufficient rest between intervals. Extend the rest—better to do one fewer repeat than to sacrifice quality on every one.

Actionable Advice for Readers of Different Levels

By now, you might be wondering: where do I actually start? I’ll give you three paths based on your level.

Just Getting Started (Riding for less than a year, no power meter)

• Don’t rush into testing CP. At this stage, your main focus should be accumulating a stable aerobic base mileage—2 to 3 times a week, at least an hour each time, at an easy intensity where you can still hold a conversation while riding.
• If you only have a heart rate monitor, you can start by using heart rate zones combined with Rate of Perceived Exertion (RPE) to get a feel for things.
• Once you have a power meter and your riding is more consistent, then move on to CP testing. Build the engine first; talk about how to use the battery later.

Advanced (Have a power meter, trained for a year or two)

• This is the group that benefits the most from the CP model. Start with a 3-minute all-out test to find your CP and W’, and write them down.
• Observe whether your W’ is relatively large or small compared to your CP to decide your training focus: if your W’ is small (like A-Zhe), add more short sprint repeats; if your CP is stagnant, do more VO2max and micro-interval work.
• Retest every 4 to 6 weeks, using the numbers to verify whether your training is effective, rather than just relying on feel.

Racing / Advanced (Targeting Wuling, KOM, race results)

• It’s recommended to use multi-stage testing (3+12 minutes, or even adding 5 and 20 minutes) to measure your power curve more completely, minimizing the error in CP/W’.
• Design your training plan around the “terrain rhythm” of your target event: for long climbs like Wuling, focus on CP as the main axis; for one-day races with repeated attacks, focus on W’ tolerance and rapid reconstitution.
• If conditions allow, work with a coach or use an advanced platform to incorporate real-time W’ expenditure and reconstitution into your race pacing strategy. This is extremely helpful for avoiding blowing up mid-race.

Second Case Study: A Long-Distance Rider with High CP and Small W’

The opposite of A-Zhe, I also coached a student who was more of a “pure endurance” type. Let’s call her Xiao-Hui. She rode along the riverside regularly and had completed several one-day Taipei-Kaohsiung rides. Her CP relative to body weight was quite good, and she was the most stable in the group on long, gradual climbs. But whenever the group ride involved hard accelerations from stoplights or a final sprint, she couldn’t keep up at all and would always get dropped.

When we tested her, sure enough: her CP was high, but her W’ was small. Her engine was great, but her battery was pitifully small. So any situation requiring short bursts of power, rapid discharge, and reconstitution put her at a disadvantage.

Our approach was similar to A-Zhe’s but with a different focus: we kept her existing aerobic base and added one “short sprint repeat” session per week—for example, all-out efforts of 15 to 20 seconds, resting 2 to 3 minutes, for 8 to 10 reps—specifically to stimulate W’ capacity and neural recruitment. At the same time, we deliberately practiced “anticipating starts” during group rides, so she would downshift and get ready before reaching a stoplight, using technique to compensate for part of her battery deficit.

A few weeks later, she reported that the most noticeable change wasn’t in the data, but that “she finally wasn’t getting dropped at every start.” What this case study is meant to tell you is: the “configuration” of CP and W’ varies from person to person; there’s no standard answer. The key is to measure it first, understand your strengths and weaknesses, and then address them accordingly. This is also why I’ve always said the CP model has more explanatory power than a single FTP number—it helps you see “whether you’re an engine type or a battery type,” and this has a huge impact on your training direction.

How to Read Your Power Curve Shape

Going a step further, once you’ve accumulated data from multiple test stages and plotted your own power-duration curve, you can observe two characteristics:

• The height of the asymptote (CP): The higher the curve levels off, the stronger your sustainable aerobic engine.
• The magnitude of the upward bulge in the short-duration range (W’): The higher the curve bulges on the left side (short durations) and the farther it is from the CP asymptote, the larger your W’ battery.

Putting these two characteristics together, you can roughly categorize yourself:

Rider Type	CP	W’	Common Performance	Training Focus
Engine type (e.g., Xiao-Hui)	High	Small	Stable on long climbs, weak at sprinting	Strengthen sprint repeats to build W’
Battery type	Medium	Large	Good explosive power, fades on long climbs	Raise CP, build aerobic base
Balanced type	Medium-High	Medium	Average across the board	Fine-tune based on target event
Developing type (Beginner)	Low-ish	Small-ish	Overall still growing	Build aerobic base mileage first

This table isn’t meant to label you, but to remind you: training isn’t about copying someone else’s plan; it’s about understanding your own curve first, then deciding what needs to be improved. The same interval workout means something completely different for an engine-type rider versus a battery-type rider.

A Reminder for Everyone

Regardless of your level, don’t let the numbers override your body’s sensations. CP and W’ are great tools, but they are models and estimates, not absolute truths. If one day your data looks great but your body feels unusually fatigued, your heart rate is abnormally high, or you experience any discomfort like chest tightness or dizziness, please stop and seek medical attention if necessary. In Taiwan, medical care is convenient and National Health Insurance access is easy—don’t push through it. Tools are meant to help you train smarter, not to push you into injury.

Conclusion: From a Single Number to a Whole Language

Back to A-Zhe’s story. After we tested his CP and W’, we found that the problem wasn’t his FTP at all, but his small W’ battery. We added targeted micro-interval and W’ depletion workouts, and a little over two months later, when he rode Fengguizui again and faced his teammates’ attacks on the climbs, he could finally hold on and keep up. He texted me: “Coach, it turns out what I was missing all along wasn’t an engine, but a battery.”

This is the most valuable aspect of the CP model. FTP gives you a single number, telling you “how hard” to go. CP and W’ give you a whole language, letting you understand “how big your engine is, how full your battery is, how fast you discharge, and how slowly you recharge.” When you can use this language to read your own body and design each interval, training upgrades from “following a prescribed plan” to “truly understanding what you’re doing.”

If you’ve been riding for a while and have a power meter, I sincerely suggest you find a cool morning and do a proper 3-minute all-out test to get to know your own CP and W’. Those 3 minutes will be painful, but your understanding of your own body will be forever changed.

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This article is for educational purposes and does not replace individual diagnosis and treatment advice from a physician, physical therapist, or nutritionist. If you have a history of cardiovascular disease, hypertension, diabetes, or other conditions, please consult a physician and perform high-intensity all-out tests under professional supervision.

References

• TrainingPeaks — FTP vs. Critical Power: Are We Measuring the Same Thing?：https://www.trainingpeaks.com/coach-blog/ftp-vs-critical-power/
• PMC Review — The Application of Critical Power, W′, and Its Reconstitution：https://pmc.ncbi.nlm.nih.gov/articles/PMC7552657/
• PubMed — A 3-min all-out cycling test is sensitive to a change in critical power：https://pubmed.ncbi.nlm.nih.gov/18685519/
• Medium — 3 minute all out test for critical power：https://medium.com/critical-powers/3-minute-all-out-test-for-critical-power-including-video-37d8befd4f01

Related Reading

• Critical Power (CP) vs FTP: Which Is Your True Threshold?
• The Science of Power Training: From Cycling to Running Power, Advantages, Controversies, and Application Boundaries
• Power Meter Training for Beginners: A Complete Guide to FTP Testing and Five-Zone Workout Design
• The Complete Guide to CP and W′: The Hyperbolic Model That Understands Pacing Better Than FTP, from Wuling to Criterium Racing