Aerobic Decoupling (Pw:Hr and Pa:HR) and Efficiency Factor (EF)

Aerobic Decoupling and Efficiency Factor are two metrics that measure aerobic efficiency.

Efficiency Factor (EF)

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What is it?

Efficiency factor (EF) is the ratio of Normalized Power to heart rate (cycling) or Normalized Graded Pace to heart rate (running) for a given activity.  An increase in this value for steady-state, aerobic endurance intensity rides may indicate an improvement in aerobic fitness.

How to find it

To view an EF of a workout, the workout must contain power and heart rate (for cycling) or pace and heart rate (for running).

  1. Open a workout in which you performed a long, steady-state effort* in your endurance training zone.
  2. In the expando, highlight the section of your workout on the graph that contains the long, steady-state effort.
  3. In the right-hand explore, look for the 'EF'.  That is your Efficiency Factor or the ratio of your NP to heart rate (NGP to heart rate for running).

*EF is only a valid metric for aerobic, steady-state workouts. Shorter intervals at higher intensities require anaerobic energy contribution which invalidates EF as an aerobic metric.

How to Use it

EF is a great tool to determine if your aerobic fitness improves over time between workouts.

  1. Perform a sustained, steady effort in your endurance zone. e.g. 2 hours at a constant endurance heart rate.
  2. Take note of your EF.  It may be helpful to write a post-activity comment with your EF number so you can easily search for it later.
  3. Repeat the workout again and take note of your EF.
  4. If your EF improves, your EF number will increase.  An increase in EF means that your output (power or pace) for the same input (heart rate) increased. In other words, you're going faster for the same input.

Aerobic Decoupling (pw:hr, pa:hr)

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What is it?

Aerobic Decoupling compares the Efficiency factor from the first half of an activity to the second half. A smaller change in EF (less than 5%) from the first half to the second half may indicate improving aerobic endurance.

How to find it

To view the pw/pa:hr of a workout, the workout must contain power and heart rate (for cycling) or pace and heart rate (for running).

  1. Open a workout in which you performed a long, steady-state effort* in your endurance training zone.
  2. In the expando, highlight the section of your workout on the graph that contains the long, steady-state effort.
  3. In the right-hand explore, look for the 'pw/pa:hr'.  That is your Aerobic Decoupling, or compares the Efficiency factor from the first half of an activity to the second half.

How to Use it

Aerobic Decoupling is a great tool to determine if aerobic endurance for a given duration and a given output is strong enough to remain aerobic for a single workout.

  1. Perform a sustained, steady effort greater 20 minutes or greater* 
  2. Open the workout in TrainingPeaks.  
  3. Highlight the effort.
  4. Your pw/pa:hr will appear for that highlighted section in the right hand explore.
  5. <5% good aerobic endurance at that duration for that power output

*Aerobic Decoupling values for efforts under 20 minutes in duration aren't as valid

Viewing EF and pw/pa:hr on the TrainingPeaks Mobile App

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EF and Aerobic Decoupling may also be viewed on the TrainingPeaks mobile app.

  1. Open the TrainingPeaks mobile app
  2. Find the workout of interest
  3. Click the workout
  4. On the tabs above, click Map/Graph
  5. Scroll down to the workout summary
  6. You will see EF and pw/pa:hr in the summary of the workout provided there's a power and a heart rate for cycling and pace or heart rate for running.
  7. Highlight sections on the graph of interest to prompt TrainingPeaks to calculate EF or pw/pa:hr for specific intervals.

 

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