Guides
What Are Power Curves in Training Apps? (Explained)
The short answer
- A power curve plots your mean maximal power: the best average watts you have held for every duration, from one second to several hours.
- Read left to right: the short end (5 to 60 seconds) shows sprint and anaerobic ability, the right end (20 to 60 minutes) shows your sustained aerobic engine.
- The shape reveals your rider type: a steep drop-off means a sprinter or punchy rider, a flat curve means a diesel time-triallist.
- Curves come from your real ride history, so they are only as honest as your power source: a consistent, well calibrated trainer matters more than the headline number.
- Use the curve to spot weaknesses and to track progress over a season, not to judge a single ride.
A power curve is a graph of your mean maximal power: for every duration, from one second up to several hours, it shows the highest average watts you have ever held for that long. Training apps such as Zwift, TrainerRoad and intervals.icu build it automatically from your ride history, then plot watts on the vertical axis against time on a logarithmic horizontal axis. Read the shape and you can tell whether you are a sprinter, an all-rounder or a diesel time-triallist, and exactly where your weaknesses lie.
I have spent the last three winters staring at my own power curve on the turbo. Below is how I read it with the riders I coach, what it can and cannot tell you, and how to make sure the numbers are honest before you trust them.
What a power curve actually is
Every time you ride, your head unit or app records a power reading roughly once per second. A power curve takes that whole history and asks a simple question at every duration: what is the best average power you managed to hold for one second, for five seconds, for one minute, for twenty minutes, and so on?
The result is “mean maximal power”, often shortened to MMP. Plot each of those best efforts and join the dots, and you get a line that starts very high on the left for the shortest durations and slopes downwards to the right as the durations get longer. That is your power curve.
Most apps draw the time axis logarithmically, so the gap from one second to ten seconds takes up as much width as the gap from ten minutes to one hour. That stops the short, spiky efforts being squashed into the corner and makes the whole curve readable.
How to read it: left to right
The easiest way to make sense of the curve is to split it into four regions. Here is how I talk through it with riders.
| Duration | Energy system | What it shows | Typical effort to set it |
|---|---|---|---|
| 1 to 15 sec | Neuromuscular | Raw sprint power | Standing sprint, gate start |
| 15 sec to 2 min | Anaerobic | Punch and repeatability | Short hill, attack, micro-bursts |
| 2 to 8 min | VO2 max | Top-end aerobic ceiling | 5 min test, hard intervals |
| 10 to 60 min | Threshold / aerobic | Sustained engine, FTP | 20 min test, long tempo block |
The far left of the curve (one to fifteen seconds) is your neuromuscular sprint: pure peak watts. The next section out to about two minutes is anaerobic capacity, the punchy stuff that decides whether you can follow an attack or close a gap. From roughly two to eight minutes you are looking at your VO2 max region, the top of your aerobic ceiling. And from ten minutes out to an hour you are reading your threshold and sustained aerobic engine, where your FTP lives.
A point worth remembering: your FTP is just one spot on this curve, around the 20 to 60 minute mark. The curve is the whole story, FTP is a single sentence from it. If you want the deeper version of this, I cover it in my guide to understanding power readings on your turbo trainer.
What the shape says about your rider type
The single most useful thing the curve tells you is your rider type, and you read that from its shape rather than the absolute numbers.
The sprinter or punchy rider
A curve that launches very high on the left and then drops away steeply belongs to a sprinter or a punchy criterium rider. Big peak watts, big one-minute power, but the line falls off a cliff before you reach the long durations. These riders win bunch sprints and short, sharp climbs but suffer on a long drag.
The time-triallist or diesel
A flatter curve that does not fall away much from five minutes out to an hour belongs to a diesel: the classic time-triallist or sustained climber. The peak watts may be modest but the engine just keeps going. On the turbo these are the riders who quietly grind out a brutal sweet-spot block and barely change colour.
The all-rounder
Most of us sit somewhere in between, with no dramatic spikes and no glaring dips. That is fine, and it is often the most useful starting point for structured training because you can develop in any direction.
Where to find your power curve
You almost certainly already have one. The most common places riders look at it:
- Zwift Companion / zwiftpower shows your best efforts and a power profile after each ride.
- TrainerRoad has a dedicated power curve view in your career and career progressions.
- intervals.icu is the one I use most: free, brilliant, and it lets you compare any two date ranges on the same chart.
- Strava (with a subscription) shows a power curve under your analysis tab and lets you compare time periods.
- Garmin Connect plots a power curve from any rides recorded on a Garmin head unit.
If you want to understand how that ride data gets out of one app and into another so you can build a fuller picture, I have a full walkthrough on how to export your training app data.
How honest is your curve? Check the power source
This is the part most articles skip, and it is the part I care about most as a coach. A power curve is only as truthful as the data feeding it. Garbage power in, a flattering or misleading curve out.
Years of testing trainers have taught me to treat the curve with suspicion until I know the power source, because the differences matter:
A solid direct-drive trainer like the Tacx Flux 2 tracks within roughly a couple of percent of my pedals, so its curve is trustworthy. A cheaper wheel-on or, worse, an estimated “virtual power” setup based on speed and a resistance table can be wildly off, especially in the short, spiky efforts that define the left of your curve. A spongy tyre or an inconsistent roller pressure adds noise on top.
Using the curve to actually get faster
A power curve earns its keep in two ways: finding weaknesses and tracking progress.
To find weaknesses, look for the duration where your watts per kilo sits furthest below where you want it. Then train it deliberately. A weak two to four minute section calls for VO2 intervals. A weak one-hour section calls for threshold and sweet-spot work. A weak sprint calls for short maximal efforts with full recovery.
To track progress, compare the same 90-day curve across different points in your season. On intervals.icu I overlay my winter base curve on my spring curve and you can literally watch the threshold section lift after a block of sustained work. This is far more honest than chasing a single FTP number, because it shows whether you actually improved at the duration you trained.
For the bigger picture of how apps stitch all this together over time, see my guide on how training apps track progress. And if you want to build the sessions that move specific parts of the curve, start with structuring a basic turbo training session.
My coach’s verdict
The power curve is the single most useful chart in any training app, and most riders barely glance at it. Used well it tells you what kind of rider you are, where your weak link sits, and whether a block of training actually worked. Used badly, on a noisy or estimated power source, it just gives you a number to fool yourself with.
So my advice is simple: get yourself a consistent, accurate power source, set real maximal efforts across the durations you care about every few weeks, and read the curve as a season-long trend rather than a verdict on today’s ride. Do that and it becomes the most honest training partner you have, far more honest than the rider staring back at you from the garage wall.