Variability Index (VI)

Variability Index (VI) provides a deeper insight into the physiological demands of a workout or Event.

What is Variability Index (VI)?

Variability Index (VI) is the ratio of Normalized Power to Average power for a workout or workout selection. The greater the VI, the more variable and less continuously aerobic the effort.

What do I need to calculate VI?

For TrainingPeaks to calculate VI for your ride or segment of the ride we require three things:

  1. You need a power meter.
  2. A device that records the power channel from your power meter e.g. Garmin, Wahoo, Suunto device.
  3. A power threshold that is specific to your completed workout.  Make sure that you have a power threshold set in your account settings.

Where can I find my workout's VI?

Workout Expando Summary


Workout Expando Selection


TrainingPeaks Mobile App


VI reference values

Variability Index for Common Rides

Type of Ride Variability Index
Steady isopower workout (endurance ride) 1.00-1.02
Flat Road Race 1.00-1.06
Flat Time Trial 1.00-1.04
Hill-Climb Time Trial 1.00-1.06
Flat Criterium


Hilly Criterium 1.13-1.50
Hilly Road Race 1.20-1.35
Mountain Bike Race/Cyclocross Race 1.13-1.50


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