Normalized Power (NP)™
by Andrew R. Coggan, PhD

Normalized Power™ (or adjusted power) incorporates two key pieces of information:

1. The physiological responses to rapid changes in exercise intensity are not instantaneous, but follow a predictable time course.

2. Many critical physiological responses (e.g., glycogen utilization, lactate production, stress hormone levels) are curvilinear, rather than linearly, related to exercise intensity.

By taking these factors into account, normalized power provides a better measure of the true physiological demands of a given training session - in essence, it is an estimate of the power that you could have maintained for the same physiological "cost" if your power output had been perfectly constant (e.g., as on a stationary cycle ergometer), rather than variable. Keeping track of normalized power is therefore a more accurate way of quantifying the actual intensity of training sessions, or even races.

For example, it is common for average power to be lower during criteriums than during equally-difficult road races, simply because of the time spent soft-pedaling or coasting through sharp turns during a criterium. Assuming that they are about the same duration, however, the normalized power for both types of events will generally be very similar, reflecting their equivalent intensity. In fact, normalized power during a hard ~1 hour long criterium or road race will often be similar to what a rider can average when pedaling continuously during flat 40k time trial - the normalized power from mass start races can therefore often be used to provide an initial estimate of a rider's threshold power.

Normalize Power (NP)™, Intensity Factor (IF)™, and Training Stress Score (TSS)™ are all registered trademarks of Peaksware, LLC.