Normalized Power in cycling

When using a power meter, on the road or on an indoor trainer, the normalized power (or weighted average power, Normalized Power or NP) displayed on your bike computer or in your activity report is more important than average power. We explain why.

By Guillaume Judas – Photos: ©Sram/©Shimano

For cyclists and triathletes, normalized power is one of the most critical metrics to understand, but also one of the most useful. It is an adjusted measure of an activity’s average power, which more accurately reflects the intensity level of that activity.

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Power measurement in cycling, whether through a power meter in the bottom bracket, pedals, hub, or indoor trainer’s transmission mechanism, has become popular in recent years and has allowed many practitioners to progress by optimizing their training time. Indeed, power measurement instantly reflects the intensity level of an exercise, unlike heart rate measurement, which always reacts with a time lag.

=> SEE ALSO: Power Meter User Guide

But power data can sometimes be difficult to interpret. Not all efforts are equal in terms of energy cost, and small variations or increases in intensity can completely change your perception of effort as well as your ability to achieve your goal. This is why the notion of average power inaccurately reflects the difficulty of an effort, and why normalized power is more appropriate for comparing rides with each other.

Why is average power not always relevant data?

Anyone with a minimum of experience using a power meter knows that it is difficult to maintain constant power when intensity is high. And it is precisely in these conditions that average power proves interesting to note, on a climb, a time trial, or a 5 or 20-minute test for example, because it defines your fitness level and serves as a reference for determining training intensities that will aim to help you progress.

=> SEE ALSO: The different training intensities

However, average power loses all meaning in other conditions, such as over the total length of a training session taking into account warm-up, cool-down, or traffic conditions, during a race, or during a ride with other cyclists. In a race, for example, there are many moments when you stop pedaling, caught in the slipstream of the peloton, but where you have to push very hard during accelerations out of corners or to follow or initiate attacks. These repeated accelerations are very costly in terms of energy and disrupt your effort management. The average power of a race can be surprisingly low compared to the actual difficulty. Whereas, conversely, a session at a stable and regular intensity on a flat, traffic-free road or on an indoor trainer can show an equivalent or higher average power without the effort being comparable.

Wanting to follow the average power of a ride can also lead to the same excesses as only being interested in the average speed of a ride. By seeking to optimize training time by only considering this value, you might be tempted to look for the most favorable terrain to maintain sustained average power, or to neglect the recovery periods necessary for good progress. In other words, referring to average power is most often counterproductive. Hence this notion of normalized power, which is more reliable for assessing the intensity level of training sessions or competitions.

=> SEE ALSO: How to improve average speed?

Reference value

Developed by Dr. Andrew Coggan (the inventor of the famous FTP test) in the mid-2000s, normalized power reflects the disproportionate metabolic cost of high intensities, by weighting intense efforts and minimizing periods of low-intensity pedaling. Simply put, while average power is a simple reflection of the power you actually produced during a ride, including coasting periods, normalized power approximates what you could have done with the same level of effort, had you ridden at a perfectly steady pace.

The calculation of normalized power results from a complex algorithm, fortunately now integrated into all bike computers that support power meters, as well as into GPS data analysis platforms for races or training such as Strava, Garmin, Wahoo, Hammerhead, etc. On your bike computer, you can choose to display average power (not very relevant over the duration of a ride) and/or normalized power.

The democratization of power meters raises the question of their proper use.

Normalized power is also widely integrated into other metrics in most software that evaluates training difficulty or load, such as Intensity Factor, or Training Stress Score. But you can also use this concept to directly analyze your performance and guide your efforts. Normalized power can serve as a reference in a sportive to help you determine if you are adopting a good pace relative to your abilities, for example, by avoiding starting too hard. By checking your normalized power 20 or 30 minutes after the start of the event, you can assess whether you risk overdoing it or if you have every chance of finishing in the best conditions.

Personally, I display three power data points on my bike computer when using a power meter: power smoothed over 3 seconds (easier to follow than instantaneous power), the normalized power for the entire ride, and the average power between two intermediate times, which allows me to use this value only during a very specific exercise, i.e., when it is relevant as explained above. Because it is the display of normalized power that allows me to compare the intensity from one ride to another.

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