I am new to training with power. What is the difference between average power and normalized power? Is there any relationship between two of them? Would using normalized power for IM pacing be a good strategy?
If I ride some hard intervals- should I have average or normalized power on my Garmin?
thanks !
Average power is just what it says, straight forward averaging of all the individual power readings assuming your power meter is set to record all power values (i.e. include zero values) and doesn’t have any ‘smart recording’ enabled.
Normalized power is intended to estimate the effective steady state stress put on your body by bursty non steady efforts. It basically attempts to estimate the way short intense bursts above your average power with short rests or easier periods stresses you or looked at another way it estimates the effective steady state average power that would cause the same stress as the actual bursty ride that you did. Normalized power really only applies to longer efforts as in 20 to 30 minutes or longer and shouldn’t really be applied to very short efforts.
Not everyone buys into the NP premise or the math behind it so some like it, some don’t but personally I find it useful for evaluating certain types of rides like hard punchy group training rides or racing criteriums or other bursty events. But in the end average power is what drives the bike regardless of the stress the body may feel so for purposes like predicting speed for a given power, AP is where it’s at and NP is best used for estimating things like effective training stress.
NP is also used to derive other power metrics like Intensity Factor (IF), and Training Stress Score (TSS) and the related short and long term daily average of that stress score (ATL and CTL). So it plays into other power metrics but again for those that don’t buy into the NP idea or the math behind it those other metrics are suspect as well.
Google ‘power411’ for some good reading on these and other power training concepts.
-Dave
NP can also be useful for pacing long, hill or technical time trials.
If you know from training that your best ironman effort is, say 200 watts, but the race in question is very hilly, you will want to pace higher power on the uphills and lower on the downhills and try to hit around 200 NP rather than AP, which might end up being too hard.
AP is straightforward - the average of recorded values.
NP is a mathematical model that essentially represents the body’s response to mixed intensity efforts. In other words, NP is roughly the perceived average power of your ride, had it been a steady effort.
More specifically, power values are weighted based on their proximity to some reference value (say, AP). If you attack a hill, then noodle down the back side, the two efforts may balance each other out when averaged. However, the physical expense of attacking the hill causes greater specific stress than the same duration at AP. Accordingly, NP is a representation of cumulative stress, over a specified duration.