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 or equivalent training portal. But make sure your zones are set correctly in both you're training software and your head unit for these values to be accurate.
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.
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 normalised instead of average power is generally used for triathlon race pacing or any race pacing.
Intensity Factor (IF)
While average and normalised 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 normalised 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.