Originally Posted by
chaadster
Normalized Power is not a measure of power, it is an expression of power variability in a workout, used for the assessment of training load and intensity.
It is the exact purpose of NP to reveal how a workout was done, i.e whether it was steady-state efforts or included peaky, high power, by comparison to average power. You could go in and look at a ride file or use graphs to see the same thing and get an understanding of the physiological cost of a ride, but having numbers like AP and NP make that really easy to do.
To an extent, doing a solid warmup and cooldown can toss the NP and that revelation. In an effort to burn some more KJ's, I've been adding some lower Z2 work at the end of my harder workouts. I'm already suited up and on the trainer, another 15-20min won't kill me. And is often a good cooldown.
Doing that though will give a lot lower NP than if I did a 2min warmup, slammed out intervals, then hit "stop" the second I finish the last interval. And honestly, I see riders do this for outdoor rides a LOT because the data "looks" cooler to have a faster average speed and higher NP than logging that warmup and cooldown.
This is why I say NP is more of an input to the things that really matter.
The ONE thing even Zwift gets right out of all the things it gets wrong is giving you the little "stars" for each rep you hit on target. Compliance. Compliance against the time in each zone the workout was designed to make you do. If you don't get many stars, you set your targets too high or something.
It's all about workout compliance and hitting the prescribed time in the prescribed zones. Not about the NP. NP is just a math way of simply aggregating that data into the TSS.
Best way I can put this is an example, which of the below will provide a gain in fitness and illustrates "compliance"?
Goal: 1 hour of VO2 work in the week
Athlete A: athlete hits 250w NP and 200 AP for three 30min workouts in a week........but only accumulates 15min of VO2 work
Athlete B: athlete hits 220w NP and 200 AP for three 75min workouts in a week........accumulates 60min of VO2 work, 20min per workout
So, athlete A demonstrates a pattern that may lead you to think they nailed some VO2. Solid NP. But didn't. Athlete B did a good long warmup and cooldown while hitting their 20min VO2 per workout. But had a lower NP.
Which was compliant in the plan to work on VO2?
Clearly athlete B.
The ONE time I would really pay attention to NP is for time trial or a triathlete. Your AP and NP should be pretty damn close for a good race. It makes for good data analyzing your race there. Or it could reveal how efficient you are in a road race or crit. NP is good for post race analysis, not so much for workouts.
IMO.