You may have noticed that in some intervals your average power is lower than your normalized power (NP). How can this be?

Normalized power is generally considered invalid for durations less than 20 minutes. It used to be hidden in both WKO and TrainingPeaks, but we had a great deal of people asking to see it despite the invalidity of the data.

Let's say you did 1 minute very hard and 1 minute off, repeating for 10 minutes. The normalized power would weight the "on" intervals so heavily that it would be an unrealistic report of what you could do for 10 minutes. The measurement doesn't become an accurate representation of the physiological toll until at least 20 minutes.

For very short intervals, normalized power can be lower than average power. This is because that when calculating normalized power, each data point in the selected range is calculated using the entirety of the 30 seconds prior to itself, which is the basis of NP. The accumulation of stress in your muscle at any point in time is affected by what has happened in the prior 30 seconds of any data point in question.