Normalized Power vs. Average Power?

Discussion in 'Power Training' started by lnyndhlp, Jul 3, 2008.

  1. lnyndhlp

    lnyndhlp New Member

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    I've found that the averge power I get from the Mean Maximal Average Power Curve in the WKO+ software is fairly accurate for determining the power I can maintain for most local training rides. I don't expect it to be as accurate when it comes to TTs because it's a closed course and the curve I have was made over local routes which includes a lot of hills and the occasional stop. I was wondering if anyone had an opinion on whether the Mean Maximal Normalized Power Curve would be better for estimating the power I can sustain for prolonged periods on a closed course.


    As a follow up question, what can I learn from the NP that I can't from the AP?

    Thanks
     
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  2. daveryanwyoming

    daveryanwyoming Well-Known Member

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    That depends on how you ride courses during training. If your courses are ridden with big power bursts followed by easier periods you might find your NP for typical rides is higher than AP and a better estimate of your abilities. But I base TT pacing off of the AP of my typical long (20-40 minute) training intervals performed on roads without traffic stops or interruptions, not NP.
    The effective metabolic stress on your body during a ride that isn't very steady. It's very useful for understanding why a crit for instance is hard even when the average power isn't all that high. Coasting in the corners tends to drive AP down for a ride like that but the jumps out of the corners are pretty tough lap after lap. AP alone would make you think a crit is a pretty easy ride and would be easy to recover from (not too much overall stress) but NP does a better job of accounting for all those power spikes and the training stress they create.

    -Dave
     
  3. Alex Simmons

    Alex Simmons Member

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    Whether a planned workout is feasible.
     
  4. lnyndhlp

    lnyndhlp New Member

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    How do you mean?
     
  5. kmavm

    kmavm New Member

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    Suppose you're training L5, and your current FTP is 250 (just to have round numbers). You've been doing 5x5s (with 3 minutes of active recovery) for the last couple weeks, and you're beginning to adapt to them, so you schedule, let's say, 8x5s this week. You're doing these intervals at, say, 300W.

    My NP spreadsheet suggests you wouldn't be able to finish this 8x5 workout. 8 segments with 5 minutes of 300W and 3 minutes of 150W yields a normalized power of about 270W, over a little less than one hour.
     
  6. kmavm

    kmavm New Member

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    (Oops: 8 * 8 minutes is a little more than an hour, not a little less.)
     
  7. daveryanwyoming

    daveryanwyoming Well-Known Member

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    Or to be really explicit, your ability to do a certain workout is limited by both the average power you can sustain for the duration and the normalized power you can sustain for the duration.

    For short interval efforts with high peak power followed by short rests the average power might be within your capabilities but it's very possible that the normalized power is beyond what you can sustain for the length of the workout.

    It gets back to what I said above, normalized power models the effective stress created by non steady efforts. If that effective stress is higher than you can sustain for the duration you won't be able to complete the planned workout.

    -Dave
     
  8. Animator

    Animator New Member

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    Is this something that you wrote? It sounds fun to play with.
     
  9. kmavm

    kmavm New Member

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    It's just the NP algorithm in spreadsheet form: a column for segment time (A), one for segment AP (B), an intermediate step of A*B^4 (C), and finally (SUM(C) / SUM(A))^(1/4). Nothing fancy. Almost anybody with better Excel skills would put together something nicer... Note that the user is responsible for making sure the segments are greater than 30 seconds.
     
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