You know your FTP. You probably know it to the watt. You might even know what percentage of your body weight it represents, because you've plugged the number into a W/kg calculator at least once this season.
And that's fine. FTP is useful. But if it's the only number shaping your training decisions, you are steering with one headlight on a dark road. You can see what's directly ahead — your threshold — and nothing else. Not the five-second sprint that wins the town sign. Not the five-minute effort that decides whether you hold the wheel on a steep climb. Not the sixty-minute capacity that determines whether your twenty-minute test actually represents something you can sustain in a race.
Your power-duration curve is the full picture. It plots your best power output across every duration from a handful of seconds to several hours, and its shape — not just its height — tells you what kind of rider you are, where your weaknesses sit, and what to do about them. Most amateurs have never looked at theirs. This is how to read it and act on it.
What the Power-Duration Curve Actually Is
The concept is simple. Take every ride you've done over the past 90 days. For each one, software identifies the highest average power you held for every possible duration — your best 5 seconds, best 1 minute, best 5 minutes, all the way out to your longest continuous effort. Then it takes the best of those bests across all rides and plots them on a single chart. Time on the horizontal axis, power on the vertical.
What you get is a curve that starts high on the left (short, explosive efforts) and sweeps down to the right (long, aerobic efforts). Every rider produces this general shape. The differences are in the steepness, the flat spots, and the drop-offs.
Andy Coggan and Hunter Allen formalised much of this thinking in Training and Racing with a Power Meter, and Coggan's original power profiling work categorised riders by comparing their outputs at specific durations against population data. Tim Cusick then built the power-duration model inside WKO specifically because he saw that coaches needed a way to look at the whole curve, not just one slice of it.
Why FTP alone is not enough
FTP sits at roughly the 40-to-70-minute mark on your curve, depending on which definition you use. It tells you how much power you can sustain near your lactate threshold. That's important — it correlates well with time trial performance and it anchors your training zones.
But it tells you nothing about what happens above or below that point. Two riders can have an identical FTP of 280 watts and have completely different racing experiences. One drops everyone on the short, steep kick. The other gets annihilated on it but rides everyone off his wheel once the road flattens. Same FTP. Different curves. Different riders. Different limiters.
If you train exclusively based on FTP, you will improve the part of the curve near FTP and leave everything else more or less where it was. That might be exactly the right strategy — if your FTP is actually your weakest point relative to the rest of your profile. But for many riders, it's not. And the only way to know is to look at the whole curve.
How to Build Your Power-Duration Curve
You need data. Specifically, you need power data across a range of durations, ideally from the past 90 days of riding.
The automatic approach
If you use WKO5, it builds the curve for you from every ride you upload. It also fits a mathematical model to the curve and extracts key metrics — critical power, FRC (functional reserve capacity, closely related to W'), and Pmax — that describe the curve's shape in a few numbers.
Intervals.icu does something similar, for free. Upload your rides and it will show your power-duration curve with percentile rankings at key durations.
TrainingPeaks shows a power-duration chart in the dashboard, and if you have Premium, it lets you compare curves across different time ranges.
Garmin Connect and Strava both have basic power curve views. Less sophisticated, but enough for the general shape.
One caveat: the curve is only as good as the data feeding it. If you've spent 90 days doing nothing but Zone 2, the left side — the short, hard durations — will be artificially low. Not because you've lost that capacity, but because you haven't tested it. The curve reflects what you've done, not necessarily what you can do.
The testing approach
For a more deliberate picture, you can test specific durations directly. A useful protocol:
Day 1 — Neuromuscular and anaerobic
- 3 x 5-second all-out sprints (full recovery between)
- 10 minutes easy
- 2 x 1-minute all-out efforts (5 minutes recovery between)
Day 2 (48 hours later) — VO2max and threshold
- 1 x 5-minute all-out effort
- 15 minutes easy
- 1 x 20-minute all-out effort (your standard FTP test)
Day 3 (48 hours later) — Sustained
- 1 x 60-minute effort at best sustainable pace (this is the truest FTP test but very few people do it because it's brutal)
That gives you five anchor points — 5 seconds, 1 minute, 5 minutes, 20 minutes, 60 minutes — which is enough to sketch the shape of your curve and identify where the gaps are. You don't need lab equipment. You need a power meter, a road or a turbo, and the willingness to go properly hard on test day.
Reading the Curve: The Five Key Durations
Each point on the curve tests a different physiological system. Five durations matter most for practical training decisions.
5 seconds — Neuromuscular power
This is raw sprint capacity. How much force can your neuromuscular system produce in a very short burst? It's driven by muscle fibre recruitment, fibre type composition, and neural efficiency. Very little aerobic contribution at this duration — it's almost entirely the phosphocreatine system.
What it tells you: Can you contest a sprint? Can you punch over a short, steep rise without losing contact? Can you close a gap in a few pedal strokes?
1 minute — Anaerobic capacity
A maximal one-minute effort sits heavily on your anaerobic glycolytic system. Your aerobic engine is working, but the effort is well above what it can sustain, so anaerobic pathways are covering the deficit. This is closely related to what Alex Welburn and other researchers call W prime (W') — that finite battery of work above critical power. Your one-minute power gives you a rough sense of how large that battery is.
What it tells you: Can you survive a hard attack? Can you ride over a 2-minute climb without emptying the tank? How much work can you do above threshold before you crack?
5 minutes — VO2max power
Five minutes is the classic duration for assessing your maximal aerobic power. The effort is long enough that your aerobic system is carrying most of the load but short enough that a high-quality effort pushes you to your VO2max. This is the duration that separates riders on climbs between 8 and 15 minutes — the kind of climbs that show up in most amateur road races and sportives.
What it tells you: How strong is your aerobic ceiling? When the road goes up for five to fifteen minutes, are you hanging on or riding away?
20 minutes — Threshold proxy
The standard FTP test duration. Most coaches apply a 0.95 correction factor (multiply your 20-minute power by 0.95 to estimate FTP) though that correction varies between individuals. Twenty minutes is long enough that you can't bluff it with anaerobic power but short enough that pacing errors don't completely derail the result.
What it tells you: How much power can you sustain for a meaningful block of time? This is your time trial engine, your ability to ride at the front, your capacity to set tempo on a long climb.
60 minutes — True threshold and endurance
If you've ever done a proper hour of power, you know this is a different animal from 20 minutes. Many riders find their true 60-minute power is lower than 95% of their 20-minute power — sometimes significantly. The 60-minute mark also starts to reflect your fatigue resistance and fuelling capacity. Run out of glycogen or pace badly and your power collapses.
What it tells you: Can you actually sustain what your FTP number suggests? Is your endurance deep enough for long races, gran fondos, and multi-hour events?
Putting it together
| Duration | Primary system | What it reveals | |----------|---------------|-----------------| | 5 sec | Neuromuscular (phosphocreatine) | Sprint, gap-closing, punch | | 1 min | Anaerobic capacity (W') | Surge tolerance, above-threshold work | | 5 min | VO2max / maximal aerobic | Climbing, attacking, high-end aerobic | | 20 min | Threshold proxy | Time trialling, tempo, sustained power | | 60 min | True threshold + endurance | Race sustainability, fatigue resistance |
Rider Archetypes: What Shape Is Your Curve?
Coggan's original power profiling work identified distinct rider types based on which part of the curve is strongest relative to the rest. These archetypes are simplifications — most real riders are blends — but they're useful for understanding tendencies.
The sprinter
Curve shape: Very high on the left (5 seconds, 1 minute), drops sharply as duration increases. The slope from 1 minute to 5 minutes is steep.
Strengths: Town-sign sprints, short kickers, crits with a bunch finish, closing gaps in a few seconds of raw power.
Weaknesses: Sustained climbs, time trials, anything where the effort lasts more than a few minutes without rest. Gets dropped before the sprint ever happens.
The good news: Your neuromuscular wiring is already working. Building the aerobic base underneath — VO2max work and threshold training — lets you reach the finish with the group so you can actually use that sprint.
The puncher
Curve shape: Strong through 1 minute and 5 minutes, with a noticeable drop-off at 20 minutes and beyond. Not a pure sprinter, but explosive enough to hurt on short climbs and aggressive enough to attack.
Strengths: Short, steep climbs. Attacks. Surges in the peloton. Races with a lot of variability.
Weaknesses: Flat time trials. Long, steady climbs. Anything where raw aerobic endurance matters more than repeated bursts.
Typical limiter: The sustained end. Punchers often have strong anaerobic systems and decent VO2max power but lack the metabolic efficiency and fatigue resistance for long, steady efforts. Threshold and sub-threshold work is usually where training time should go.
The time trialist (the diesel)
Curve shape: Relatively flat across 5 minutes, 20 minutes, and 60 minutes. The curve doesn't drop much as duration increases. But it might not start very high on the left — five-second and one-minute power can be modest.
Strengths: Anything sustained. Long climbs, time trials, breakaway attempts, riding on the front in crosswinds. These riders are engines.
Weaknesses: Matching surges. When the race goes on and off — attacks, steep kickers, crit-style racing — the diesel can't respond to the spikes. Gets gapped by riders who aren't as strong overall but can produce short bursts of much higher power.
Typical limiter: Neuromuscular power and anaerobic capacity. The battery above threshold (W') is small. Sprint and high-intensity interval work — short, sharp efforts at maximal or near-maximal intensity — build the top end without compromising the diesel's strength.
The all-rounder
Curve shape: No single standout duration. All categories sit at roughly the same percentile. The curve is smooth and proportional.
Strengths: Flexibility. The all-rounder can compete in different types of events and isn't a liability in any specific situation.
Weaknesses: May not be the best at anything specific. In a race of specialists, the all-rounder gets out-sprinted by the sprinter, out-climbed by the climber, and out-time-trialled by the diesel.
Training approach: Focus on the demands of your target event. Racing crits? Sharpen the top end. Targeting a hilly gran fondo? Build the 5-to-20-minute range. The advantage is that you can specialise without creating a glaring weakness elsewhere.
A comparison at a glance
| Archetype | Best duration | Typical weakness | Priority training focus | |-----------|---------------|------------------|------------------------| | Sprinter | 5 sec – 1 min | 20–60 min | Threshold + VO2max | | Puncher | 1 min – 5 min | 20–60 min | Threshold + endurance | | Diesel / TT | 20 min – 60 min | 5 sec – 1 min | Sprint + anaerobic capacity | | All-rounder | Balanced | No standout | Event-specific focus |
Finding Your Limiter
Knowing your archetype is interesting. Finding your specific limiter is what actually changes your training.
Take your best power at each of the five key durations and compare them — either against population benchmarks or, more usefully, against each other.
The Coggan power profiling approach
Andy Coggan published tables that classify riders from "Untrained" through "World Class" at different durations and body weights. Find your watts-per-kilogram at each key duration and see which category each falls into.
Here's a simplified version for male riders (female benchmarks are typically offset by 15-20%, and dedicated tables exist for women):
| Category | 5 sec (W/kg) | 1 min (W/kg) | 5 min (W/kg) | FTP (W/kg) | |----------|:------------:|:------------:|:------------:|:----------:| | World class | 23+ | 11+ | 7.5+ | 6.4+ | | Exceptional | 20–23 | 9.5–11 | 6.5–7.5 | 5.6–6.4 | | Excellent | 17–20 | 8–9.5 | 5.5–6.5 | 4.7–5.6 | | Very good | 14.5–17 | 6.5–8 | 4.8–5.5 | 4.0–4.7 | | Good | 12–14.5 | 5.5–6.5 | 4.0–4.8 | 3.4–4.0 | | Moderate | 10–12 | 4.5–5.5 | 3.4–4.0 | 2.9–3.4 | | Fair | 8–10 | 3.5–4.5 | 2.8–3.4 | 2.4–2.9 |
If your FTP category is "Very good" but your 5-minute power is only "Fair," you have found your limiter. Your aerobic ceiling (VO2max) is not keeping pace with your threshold, which means your sustainable power is closer to the top of what your engine allows. You don't have headroom. VO2max work will give you that headroom.
Conversely, if your 5-minute power is "Very good" but your FTP is "Moderate," your aerobic engine has capacity that threshold training hasn't converted into sustainable output. Sweet-spot and threshold work will raise the floor to match the ceiling.
The internal comparison method
Tim Cusick talks about this approach often. Instead of comparing yourself to population data, compare yourself to yourself. Look at the ratios between your key durations:
- 5-min power as a % of 1-min power: If this ratio is unusually high (your 5-minute power is close to your 1-minute power), you are aerobically dominant but anaerobically limited. If it's unusually low, the reverse.
- 60-min power as a % of 5-min power: This tells you about fatigue resistance. A ratio above 75-80% is strong endurance. Below 70%, your stamina is a limiter.
- 1-min power as a % of 5-sec power: This tells you about anaerobic capacity relative to pure neuromuscular sprint. A high ratio suggests you can sustain above-threshold efforts well. A low ratio means you spike hard but fade fast.
This works regardless of absolute fitness level. A Cat 4 racer and a Cat 1 racer can both use it to find where their curve is weakest relative to itself.
W prime: the hidden limiter
Here's where it gets really interesting. Two riders can have the same critical power (think of it as a more scientifically rigorous version of FTP) and ride completely differently in a race, because their W prime (W') is different.
Dr Alex Welburn, who researches critical power and W' at Loughborough, explained this on the podcast in terms that make sense for training. Critical power is your sustainable ceiling — the maximum power you can hold for a very long time without accumulating fatigue that forces you to stop. W' is a finite amount of work, measured in kilojoules, that you can perform above that ceiling. Once it's spent, you're done. Drop below critical power to recharge, or blow up.
A rider with a large W' can attack repeatedly, respond to surges, and sprint after a hard race. A rider with a small W' must be more conservative — every effort above critical power costs a larger percentage of a smaller battery.
If you get dropped when the pace surges but time trial with the best in your group, your W' is probably your limiter. If you can attack all day but can't sustain the pace between attacks, critical power needs work. More on this in the Alex Welburn piece.
Training Prescriptions for Each Limiter Type
Every prescription below is fixable. None require a new set of genetics. They require the right stimulus applied consistently over 8 to 12 weeks.
If your limiter is neuromuscular power (5-second peak is low)
Your sprint is weak relative to the rest of your profile. This is common in riders who've done lots of steady endurance and threshold work but rarely go truly all-out for short durations.
What to do:
- Standing starts: From a near-standstill, sprint for 10–15 seconds at maximum effort. 6–8 reps with 3–5 minutes full recovery. The effort should be eyeballs-out. If you're thinking about pacing, you're going too long.
- Neuromuscular activation sprints: Mid-ride, include 4–6 x 8-second sprints with at least 3 minutes between. These train fibre recruitment, not fitness. You should feel fresh between efforts.
- Gym work: Single-leg press, step-ups, and reverse lunges with moderate weight build the force-production capacity that translates to pedal force. Nothing heavy enough to risk injury — think 3 sets of 8–12 reps at a weight that leaves 2–3 reps in the tank.
Frequency: Two sprint-focused sessions per week for 6–8 weeks. These are short and don't create much systemic fatigue, so they slot in alongside normal training.
If your limiter is anaerobic capacity (1-minute power is low, W' is small)
You can't sustain efforts above threshold. You spike and fade. Surges in races empty you.
What to do:
- 30/30s: 30 seconds hard (120–130% of FTP) followed by 30 seconds easy. Start with 10 minutes of work and build to 20 minutes over several weeks. These are brutally effective for expanding anaerobic capacity.
- 1-minute repeats: 4–6 x 1 minute at maximum sustainable effort for that duration, with 3–4 minutes recovery. Push hard enough that the last 15 seconds of each rep properly hurts.
- Over-under intervals: 2 minutes at 105% of FTP, 1 minute at 90%, repeat for 12–20 minutes. These teach your body to clear lactate while still working above threshold, which directly builds W'.
You can build these with the interval builder if you want to plug in your specific numbers.
Frequency: Two sessions per week, separated by at least 48 hours. This type of work creates significant fatigue. Make sure your easy days are properly easy — Professor Seiler's research on polarised training shows this isn't optional. The hard days have to be hard and the easy days have to be easy.
If your limiter is VO2max (5-minute power is low)
Your aerobic ceiling is holding you back. You might have decent FTP relative to your body weight, but your VO2max is limiting how much room you have above threshold.
What to do:
- Classic VO2max intervals: 5 x 4 minutes at 106–120% of FTP with 4 minutes recovery. The goal is to accumulate time at or near your maximum oxygen uptake. If you can talk during the work intervals, you're going too easy.
- 3-minute efforts: 6–8 x 3 minutes at 110–120% of FTP, 3 minutes recovery. Shorter work bouts can sometimes allow higher power, accumulating a strong stimulus.
- Ascending intervals: Start with 3 minutes at 105%, then 3 minutes at 110%, then 3 minutes at 115%, 5 minutes recovery, repeat. This is how some of the coaches behind Grand Tour riders structure VO2max blocks — it progressively challenges the system within a single set.
Frequency: Two VO2max sessions per week for blocks of 4–6 weeks, then back off for 2 weeks and reassess. This is the most potent and most fatiguing type of interval work. Recover accordingly.
If your limiter is threshold (20-minute power is low relative to 5-minute power)
Your engine has a high ceiling but you can't sustain power anywhere near it. This is one of the most common limiters in amateur cyclists, and the good news is it's also one of the most responsive to training.
What to do:
- Sweet-spot intervals: 3 x 12–15 minutes at 88–93% of FTP, with 5 minutes recovery. Sweet spot is effective because it provides a strong threshold stimulus with less fatigue than riding at true FTP, meaning you can do more total work.
- Threshold repeats: 2 x 20 minutes at 95–100% of FTP, with 10 minutes recovery. This is hard, full stop. But it's the most direct way to push FTP up.
- Progressive threshold rides: Start at 85% of FTP and increase by 3–5 watts every 5 minutes, holding until you can't sustain the target. This teaches pacing and builds confidence in sustained effort.
Frequency: Two to three sessions per week, depending on where you are in your season. Sweet-spot work is forgiving enough to run three times a week for 2–3 week blocks. Pure threshold work is better kept to twice a week.
If your limiter is endurance (60-minute power drops significantly below FTP estimate)
Your 20-minute test says you have a solid FTP, but in practice you can't hold it. You fade in the second half of long rides. Your races fall apart after an hour.
What to do:
- Long tempo rides: 60–90 minutes at 76–85% of FTP. Boring, yes. Effective, absolutely. This trains the metabolic machinery — fat oxidation, glycogen sparing, mitochondrial efficiency — that supports sustained output.
- Progressive long rides: Ride 3–4 hours with the final 60 minutes at low tempo (75–80% FTP). Teaches you to produce power when fatigued, which is the actual demand of gran fondos and long races.
- Fuelling practice: Endurance limiters often have a fuelling problem as much as a fitness problem. If you're not taking in 60–80 grams of carbohydrate per hour on rides over 90 minutes, fix that before adding volume.
Frequency: One long endurance ride per week (the weekend ride for most people), with one mid-week tempo session. This is patient work — expect 8–12 weeks before the 60-minute number moves meaningfully.
How the Curve Changes as You Age
This matters. If you're reading this and you're between 35 and 55, the shape of your curve is shifting whether you're training or not. Understanding how it shifts lets you train smarter rather than just training harder to compensate.
What changes first
Research consistently shows that neuromuscular power and anaerobic capacity decline faster than aerobic endurance as you age. Joe Friel has talked about this extensively — after 40, the left side of your curve starts to drop even if you're maintaining your training.
Specifically:
- 5-second power declines by roughly 1–2% per year after 40, driven by loss of type II (fast-twitch) muscle fibres and reduced neural firing rate
- 1-minute power declines similarly, as anaerobic capacity tracks closely with muscle mass and fibre type
- 5-minute and 20-minute power decline more slowly — roughly 0.5–1% per year — because the aerobic system is more resilient to ageing
- 60-minute power is the most resilient of all, because endurance is the last quality to go
What this means in practice: the curve flattens. The diesel gets more diesel. The sprinter loses their sprint before they lose their engine. For a 45-year-old who was a punchy rider at 30, the curve might now look more like a time trialist's curve — not because they trained for that, but because the top end eroded faster than the bottom end.
What to do about it
The temptation is to accept the decline and focus exclusively on what's holding up — your endurance. Don't. That accelerates the decline at the top end.
Protect your sprint. Include at least one session per week with truly maximal short efforts — 6–8 sprints of 8–15 seconds. This is neuromuscular maintenance, not a hard session in terms of systemic fatigue. Use-it-or-lose-it signalling for your fast-twitch fibres.
Keep VO2max work in your programme. Professor Seiler's research shows that VO2max is one of the strongest predictors of performance in masters athletes, and one of the most trainable at any age. Two VO2max sessions per week during a build phase — 4-minute intervals, 3-minute intervals, whatever gets you to maximal effort for 3–5 minutes — will maintain or improve your aerobic ceiling into your 50s.
Don't neglect force production off the bike. Muscle mass loss (sarcopenia) is a real factor after 40. Strength work — single-leg press, wall sits, step-ups, lunges — preserves the muscle that generates power on the pedals. Two sessions of 20–30 minutes with moderate resistance will do the job.
Recover more deliberately. The curve shifts partly because recovery takes longer. A 25-year-old absorbs three hard sessions in a week and bounces back. A 45-year-old often needs more spacing. Switching from three hard days to two, with genuine recovery between, often produces better results than forcing the same load and accumulating fatigue that never clears. Check the guide on reading your training data to monitor whether you're absorbing load or just stacking it.
The masters advantage
Here's a perspective that might reframe this for you. Masters riders who train deliberately often end up with a more balanced curve than they had as younger riders — because the natural decline at the top end forces them to address it, while their aerobic base remains robust. A 48-year-old who does sprint work, VO2max intervals, and endurance riding across the week is often a more complete rider than the 28-year-old version of themselves who just rode hard all the time and called it training.
The curve changes. It doesn't have to collapse. The riders who age best are the ones who train what's declining, not just what's comfortable.
Tracking Progress: What Improvement Looks Like on the Curve
You've identified your limiter. You've spent 8–12 weeks targeting it. How do you know if it's working?
Look at the shape, not just the height
The most common mistake is fixating on peak numbers. "My FTP went up 8 watts" is satisfying, but it doesn't tell you whether the shape of the curve has changed. What you want to see is the limiter duration improving faster than the rest of the curve.
Pull your curve from before the training block and overlay it with your current curve. Most software lets you do this — WKO has a date range comparison, Intervals.icu lets you compare time periods.
What improvement looks like:
- If your limiter was VO2max, your 3-to-8-minute range should lift while your 20-minute and longer numbers stay the same or rise slightly
- If your limiter was sprint power, the 5-to-15-second range should jump without costing you at longer durations
- If your limiter was threshold, the 15-to-40-minute range should rise, often bringing 60-minute power along with it
What over-training looks like:
- The whole curve drops. Your sprint numbers fall. Your threshold falls. Everything falls. This usually means you've accumulated too much fatigue and haven't recovered enough between hard sessions. Back off for a week before retesting.
How often to check
Every 8 to 12 weeks during a training block is a reasonable rhythm. Checking more often introduces noise — a bad night of sleep or a stressful work week can suppress your numbers without reflecting actual fitness change.
If your software builds the curve automatically, you can glance weekly as a trend indicator. But don't react to week-on-week fluctuations. Look at the 4-week rolling picture.
The numbers to track over time
Keep a simple log:
| Date | 5 sec (W) | 1 min (W) | 5 min (W) | 20 min (W) | 60 min (W) | Body weight (kg) | |------|:---------:|:---------:|:---------:|:----------:|:----------:|:-----------------:| | Start of block | — | — | — | — | — | — | | 8 weeks | — | — | — | — | — | — | | 16 weeks | — | — | — | — | — | — |
Include body weight because watts per kilogram is what matters on a climb. A rider who gains 3 watts at 5 minutes but loses 2 kg has improved far more than the raw wattage suggests.
You can plug your FTP into the zone calculator and your weight into the W/kg calculator to see where your updated numbers land against category benchmarks.
When to change your training focus
Once the limiter has improved to roughly the same category as your strongest duration — or once improvement plateaus — maintain that quality and shift focus to the next-weakest point, or enter a general phase to consolidate.
The curve is never finished. It shifts with your training, your racing calendar, your age, and your life stress. The riders who keep improving year after year are the ones who reassess regularly, identify the limiter honestly, and train it specifically rather than defaulting to whatever sessions they enjoy most.
FTP is one number. The curve is the whole story. Read it, act on it, and you'll stop guessing where to put your training energy — and start directing it where it actually counts.
If you want structured coaching built around this kind of analysis, that's what the Not Done Yet community is for — training plans, weekly coaching calls, and a room full of riders working through exactly this process. $195 a month, no fluff, just the work.