A Quick Guide To Power Terms

If you’re new to training with power, there can be a bit of a learning curve with terminology.

Photo: John David Becker

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Power what? A quick guide to help you understand power terms.

If you’re new to training with power, there can be a bit of a learning curve with terminology. Here are some common terms you will see after logging and uploading that first ride to Training Peaks. Make sure your zones are set correctly in both your training software and your head unit for these values to be accurate.

Average Power
Exactly what it sounds like, it’s a measure of your actual power over the course of the session, including zeros. Because average power does not describe the work performed during a session, it is not usually a good indicator of how fatiguing a session was.

Normalized Power
Through a complex algorithm, this is the predicted effort you could have held if you had maintained an even effort versus a variable effort. This number seeks to better quantify the relative effort of a session, thus normalized instead of average power is generally used for triathlon race pacing.

RELATED: How To Use A Power Meter In A Race

Intensity Factor (IF)
While average and normalized power are objective measures, intensity factor defines how intense a given effort is to you personally, as it is the percentage of threshold power maintained over a period of time.

Variability Index (VI)
Your normalized power divided by average power. Your goal race type, terrain and pacing plan determine optimal VI. Generally, for triathlon, a VI of less than 1.05 is desirable.

Watts per kilogram of body weight is the way to compare riders of different sizes. Performance gains can come from working on either the body weight side or the power increase side of the equation. According to Dr. Andrew Coggan’s power profile, a watts/kg ratio at threshold of 4–4.5 equates to a Cat 2 cyclist.

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