Tristar athlete, as a cyclist our power output varies due to factors like wind, terrain and even other riders around us. Here’s where Normalized Power (NP) comes in. This algorithm is complicated, but it incorporates two key pieces of information:
#1 The physiological responses to rapid changes in exercise intensity which are not instantaneous, but follow a predictable time course. Many critical physiological responses (e.g. glycogen utilization, lactate production, stress hormone levels) are curvilinearly, rather than linearly, related to exercise intensity.
#2 Your NP is an estimate of the power you could have maintained for the same physiological “cost” (in terms of glycogen utilization, lactate production, stress hormone levels, and neuromuscular fatigue) for a given effort or ride if your power output had been perfectly constant (e.g., as on a trainer) rather than variable. As such, NP is always higher than average power.
NP is a better indicator than average power of how metabolically challenging your workout was. It emphasizes power surges which require a lot of glycogen (carbs) and therefore contribute to an increase in fatigue overall fatigue rates.
An example is if you pedal at 200 watts for 1 hour, you will have an average power (AP) and normalized power (NP) of 200. If you pedal at 100 watts for 20’, 200 watts for 20’ and 300 watts for 20’ you will still have an AP of 200 watts but your NP will be 239 watts.
