Critical power (or rFTPw – threshold power) is the single-most important value to run and train with power effectively. This value tells the athlete how much power they can produce for a set time frame (that time frame varies by person) and the value can be scaled for any race duration. There are some differences between critical power and functional threshold power, but for now we will treat them as the same thing. There are several ways to estimate or determine your critical power.

Read first – Running Functional Threshold Power – A Primer (October 31, 2017)

By Steve Palladino, coach and consultant, Palladino Power Project

What is Functional Threshold Power (FTP)?

Some insight and advice on CP/FTP testing. This article is for cycling with power, but it still largely applies to testing in general, not only for cycling.


Methods for estimating CP:

  • 3/9 test
  • 30-minute time trial
  • 3/6 lap test
  • Mean-maximal power curve
  • Recent race result – using The Secret of Running table OR Stryd Powercenter.

The 3/9 test:

  • Warm up 15 minutes, preparing for a hard effort at the end of it.
  • Conduct a 3-minute interval at maximal effort.
  • Recover with a 5-minute walk, 10-minute very easy jog, 5-minute walk, 5-minute easy jog, and 5-minute walk again (30 minutes total).
  • Conduct a 9-minute interval at maximal effort.
  • Cool down 10 to 15 minutes.

Determine CP: Add the 3-minute average power value to the 9-minute average power value. Divide that total by 2. Take 90 percent of the quotient; that is your estimated rFTPw value.

Reference: Vance, Jim. Run with Power: The Complete Guide to Power Meters for Running (Kindle Locations 857-875). VeloPress. Kindle Edition.

The 30-minute Time Trial:

  • Warm up 15 minutes, preparing for a hard effort afterward.
  • Start a 30-minute time trial (best effort) on a flat road or track, collecting power data (collect pace and HR data as well, if possible).
  • Cool down 10 to 15 minutes.

Take the average power for the last 20 minutes of the time trial; this is your Critical Power

Reference: Vance, Jim. Run with Power: The Complete Guide to Power Meters for Running (Kindle Locations 896-904). VeloPress. Kindle Edition.

The 3/6 Lap Test:

  •  Warm up for 5 minutes. Do two to three 100-meter strides at approximately 80% maximum effort during warm up to enhance the blood circulation and ready your muscle for intense use.
  • Run 800 meters Easy-pace run. Two laps on a 400-meter track, please use the innermost lane. Run at an easy pace, such that you can comfortably maintain conversation.
  • Warm up for another 5 minutes.
  • Run 1200 meters Maximum-effort run. Run at a consistent pace throughout the test, but so that you are nearly exhausted at the end of the test.
  • Recovery for 30 minutes. Throughout the 30-minute recovery period, the runner should walk or jog slowly.
  • Run 2400 meters Maximum-effort run. As was the case for the three-lap run, it is important to maintain a consistent pace during this run instead of dramatically changing pace (and effort) during the run.
  • Cool down.


Reference: Stryd Powercenter

Mean-maximal Power Curve:

Once you’ve trained with Stryd for several weeks or months, you can develop your personal power-duration curve for estimating various race performances. Here, you can see my curve for the past two months of training. I don’t have any races or all-out efforts within this curve, so my CP will be estimated fairly low. Ideally, you will want to race or have all-out efforts to better estimate your CP.

Here you can see that my CP is about 293 watts and FTP is very close, at 284 watts. This is about 3.45 watts/kg and and 3.34 watts/kg, respectively.

My Mean-Maximal power Curve

Recent race result:

In this instance, you just need your last race result and the table below. Find your distance, your closest time, and then select your your estimated CP in watts/kg.

You can also use Stryd Powercenter to estimate your CP based on a recent race result in a similar fashion.

Race Day CP

Reference: Dijk, Hans; Megen, Ron; Rumery, Anne. The Secret of Running: maximum performance through effective power metering and training analysis, Meyer & Meyer Sport, 2017.