# When trying to stick to a certain power is NP a good metric to go off?

When I want to go for a Z1/Z2 ride is normalised power a good metric to try and stick to or is there something else I should be looking at for a more accurate metric?

NP is a retrospective metric. You review the ride and time spent in zone dictates the NP. So a 1hr Z1 ride with 8x15sec in Z7 will have a very different NP to average.

So whilst riding/training it is not really a useful metric.

3sec / 5sec / 10sec power or average may be better.

Hopefully a steady Z1/2 ride, all of the power metrics would be very similar. As JulesC wrote, 3/5/10 sec would be fine. Afterwards, compare NP and average power to see how variable your ride was.

Agreed with the above. Using NP may be more useful if youâ€™re doing outdoor intervals and want to compare lap average power to lap NP, if youâ€™re looking to see if youâ€™re able to maintain relatively â€śsmoothâ€ť output at your interval target. For easy riding, Iâ€™d just use the average.

I would definitely not use NP for a Z1 ride. Example - If you ride 5 minutes and pedal for :15 and then coast for 4:45 your NP is going to be useless from what your intended goal is for the ride.

3s Average is what I stick to.

Iâ€™m not convinced that 8 brief sprints would really have much of an effect on NP.

â€¦but it will give a significantly different result to average power.

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I use NP for my 70.3 races where I want the effort to stay as smooth as possible and where there are very few stops or hard accelerations.

When Iâ€™m targeting an outdoor Z1/Z2 ride I only look at 3sec power as all of the stops and coasting will drag down AP and NP.

Just to put some data to it since I was curious.

Hereâ€™s a 1h ride at 70% (207W for me) with 8x15s @ 200% (590W)

It brought the NP up to 235W and the Avg to 220W. So a pretty good increase in both. But I would argue that 8x15s sprints is a relatively intense workout. 3-4 sprints is probably more realistic

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I recently did a 90-minute zone2 ride with 6 short sprints, each about 6-10 seconds. Pulling out the 60 minute work interval, and doing a rough analysis to remove the sprints, that took VI from 1.04 to 1.12. So depending on your definition of much, it means that for a lower z2 (using round numbers) at say 150W with 900-1000W sprints that would bump NP from 156 to 168.

If you had my Z2 power and MVDPâ€™s sprint power, it definitely would

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Thanks, thatâ€™s a bit more than I expected. Still, I wouldnâ€™t call 7% â€śvery differentâ€ť (as @JulesC did).

Yeah, I think alot of it has to do with how high the power is on your sprints. For example, if those sprints are at 250% vs 200% then the NP jumps to 255. For some people 15s at 200% is a sprint while for others itâ€™s just a surge and they might hit 250-300% which would really inflate that NP.

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NP wouldnâ€™t really be representative/come into play for at least 20 minutes so itâ€™ll be kind of awkward. I would use a rolling average or just AP.

I wouldnâ€™t call holding 250% to 300% of FTP for 15 seconds a sprint, it is more like a surge. At ~400%, my 15s MMP is crap and considered by WKO, â€śrecreationalâ€ť (I need to work on my VO2, the whole region is crap).

It depends when in your program and why you are doing the ride. Some would say itâ€™ll be better to anchor to HR for these type of rides.

The other factor is that the OP said Z1/Z2 ride so whilst the calculation that MWGlow15 did was at 70% FTP the calculation was based was therefore ALL in Z2, with absolutely no time in Z1; which clarifying was part of the OPâ€™s information given.

So in these workouts I used midway through each zone and split the total w/o to 10 min in Z1 10 min in Z2 (midway through each zone) with 8x15sec at only 1% above the Z7 Threshold so there is more head room and in reality if you can hit Z7 you are not that close to 1% and most people are clear through the threshold especially for only 15 seconds (20 seconds is the typical time Z7 is able to be held) but I wouldnâ€™t want to be accused of over egging the pudding.

If these were put into MWGlow15â€™s NP calculator app it would be greater than 7% as the lower zone is significantly lower than the one s/he used. And this is consistent with my answer to the OPs request.

EDIT realised it was an Intervals.ICU facility

I think this is based on an under reading PM FTP but the difference between NP and ave is clear.

Normalised power is ok over a sufficiently long duration (seen suggestions of 20 mins +). One strategy is to build a workout where you have 20 min laps. Then over the the full ride you might complete 6 -15 laps. You can have normalised power for the lap on display. This way you are not trying to hold power precisely at any point in time but keep it in a given range over a longer interval. It is a strategy I have used. First 10 mins just easy, then into the laps, using the first one as a guide, and then trying to match that consistently throughout the ride. Clearly common sense needs to be used if a lap contains a substantial or steep climb.