Is this an example of when NP is not an accurate reflection of FTP?

Discussion in 'Power Training' started by tommyrod74, Sep 13, 2010.

  1. tommyrod74

    tommyrod74 New Member

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    So...

    I've been training with power for a coupe of months now, and have seen some improvements. My current tested 20 minute power is 270 watts (average power), so I've estimated my FTP at 251 watts. I'm 148 lbs, if that's germane for this discussion.

    I did a particularly hard crit on Saturday. It was the second crit of the day, and was a P/1/2/3 race (I'm a Cat 3, and had done the 3 race a couple of hours earlier), so I was somewhat pre-fatigued.

    I popped off the back of the front group after 6-7 laps, and continued solo, catching other dropped racers and moving up gradually, finishing 24th. For me, it was great, as it was a super-tough course and I REALLY wanted to stop halfway through.

    The course was 0.6 miles per lap. 100 feet of climbing per lap, and it was steep for a bit of it. This is relevant as it meant I spent a big chunk of time in anaerobic-land each lap. It also means that, like everyone else, I was recovering on the backside of the course, occasionally even coasting when tucked in behind someone.

    Here's the interesting thing. My average power for 57:30 of race time was 236 watts. But NP was 313 (!), a VI of around 1.4.

    So, here's my question: as a decent MTB racer (Cat 1, won 2 races this year, always a podium threat) with a well-developed anaerobic engine, does this NP just represent a nasty effort of suffer-recover-repeat that doesn't reflect any increase in FTP?

    I wouldn't even ask, but I did just spend 6 weeks just training tempo and threshold (no racing due to recovering from shoulder injury in a MTB race). Maybe the training has really helped...

    Thanks for any input, I'm new here :)
     
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  2. daveryanwyoming

    daveryanwyoming Well-Known Member

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    Yeah, it seems at least like a good example of a ride where NP for an hour may not be the best reflection of FTP.

    Seems like a good candidate for an NP buster, but hard to say if you don't have a recent reliable FTP number to compare to. But your description of the course with what I'm guessing was a hard section of out of the saddle climbing every lap is a good way to see some really high NP numbers. If you were out of the saddle going hard every lap it's pretty easy to see why it might not reflect your more typical seated FTP efforts as you're repeatedly bringing additional muscle groups into play.

    -Dave
     
  3. lanierb

    lanierb New Member

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    I'm going to go opposite of Dave and say that, provided your power meter was properly zeroed, based on this ride your FTP is almost certainly near 300 watts, and certainly much closer to 300 than to 250.

    The only caveat is that, as Dave said, it is perhaps the case that you did a lot of standing efforts during the race, and that might mean that to achieve close to 300 for an hour you would have to stand a lot. However, that's still a measure of your FTP over certain terrain.
     
  4. tommyrod74

    tommyrod74 New Member

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    A few things that might matter:

    1. I've only done 2 20 minute tests, ever. I'm likely still learning how to nail a good number on the test.

    2. IF was 1.28 for the race. I've seen 2 4+ hour rides with IF > 0.91 recently.

    3. I did the hill in the crit standing for the first 5 or 6 laps, then in the saddle except for maybe 2-3 other laps. 34 laps total. Not surprisingly, the standing climbs are higher wattage (peaks 800-1000 watts vs. 500-600 seated). Climb was ~1 minute in duration.

    So is there anything I learn from this file? I guess at least I can safely assume I should retest FTP.

    Thanks again for the help, really trying to learn how to use this to improve my weaknesses (TT power, sprint) and maintain my assumed strength (anaerobic efforts).
     
  5. daveryanwyoming

    daveryanwyoming Well-Known Member

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    Yeah, 4 hour rides at .91 aren't impossible but they're still very stout rides that should leave you trashed. Well basically any rides racking up 300+ TSS are very big days so that's a clue that your FTP might currently be lowballed and supports Lanier's thoughts.

    But other things you can take from that are that 34 minute long repeats at the power range you listed says very good things about both your AWC/one minute power and your sustainable power since you continued to recover from them at least enough to finish the race.

    You also mentioned how hard the race felt and how badly you wanted to stop before the end. Have you ever dug that deep during a 20 minute training interval or testing session?

    FWIW a lot of us don't put a lot of faith in the 95% of 20 minute approach to establishing FTP. If you do regular 20+ minute intervals in training on steady terrain what do those numbers look like? If you do those off road or on rolling, non steady terrain what does the NP from those or longer efforts (aside from that crit) look like?

    Sounds to me like you've got more fitness and more FTP than you thought, you should be able to do a lot with those kind of numbers at 67 kilos...
    -Dave
     
  6. tommyrod74

    tommyrod74 New Member

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    Those 2 rides I mentioned were 4:10 and 4:13 in duration, and TSS of 346 and 352, respectively. Wasn't trashed afterwards but was certainly tired. The first ride I was chasing down a group ride from behind for the first hour and set my best hour power (229 avg, 255 NP) during that hour.

    Last 2x20 set was 251 and 248 (avg and NP identical, good flat roads). Try to do intervals on flat or slightly rolling terrain.

    And nope, they didn't hurt nearly as hard as that crit:)
     
  7. tommyrod74

    tommyrod74 New Member

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    Peak 20 minute power in a 2 hour group ride recently was 292 NP (227 avg)...
     
  8. daveryanwyoming

    daveryanwyoming Well-Known Member

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    I'm with lanierb, your FTP is closer to 300 watts than 240.

    The question is why you don't see anything near that for 20 minute training intervals on steady terrain. Do you have sustained sections of road without traffic stops, are you able to pace steadily or do you go out hot and fade? Some folks struggle to do iso-power and TT like Threshold efforts, but most don't have peak 20 minute APs nearly 20% below their repeatable hour long NPs. Are you using the same PM for these rides?

    -Dave
     
  9. tommyrod74

    tommyrod74 New Member

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    Same PM, yeah, though it's been back to Saris 3 times in the last 6 weeks for recalibration... it works fine until it doesn't. Zeroing torque regularly. To their credit, Saris has been great with turnaround and hooked me up with a great deal on a Joule head unit for my trouble.

    I may (due to the MTB background) just be really conditioned to peaky efforts and short recovery periods, and better able to post good numbers that way than in a TT (isopower? is that the word?) type effort.

    I'm decent at CX, too, and went to Cat 2 within my first 6 races... similar to MTB efforts, I guess.
     
  10. wfrogge

    wfrogge New Member

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    This....


    Myself I come from a speed skating background and can do surges and short attacks like nobody's business but can never lay down a decent 20 minute or 1 hour FTP test to reflect the NP numbers I have seen in hard crits or road races (hour or longer events).... I feel your pain :)
     
  11. tonyzackery

    tonyzackery Well-Known Member

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    Yep, any 'up and down', hill repeats type crit course will give you an inflated NP number. The Tuesday night crit course in Vancouver (at UBC) is exactly this (even without the out-of-saddle efforts) and I usually get NPs in the neighborhood of 30-40w greater than my FTP...
     
  12. Alex Simmons

    Alex Simmons Member

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    NP is what it is, provided the algorithm has been correctly applied and the input data is valid then NP itself won't be inflated. Something to check is some head units (e.g. Garmins) can screw with the data making any calculation of NP suspect.

    What might be inflated however is our interpretation of what NP is telling us.

    Nevertheless (and provided NP calculation properly applied and input data is accurate), then NP from a hard 1 hour race like this will still be closer to FTP than Average Power will be.
     
  13. tonyzackery

    tonyzackery Well-Known Member

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    NP taken from Saris' Power Agent software.
    Head unit - Saris' CPU Powertap Comp wired.
    NP 387w for 30min, 'up and down' crit. At least 30-40w (more like a good 50w) above my FTP.
    Did I leave out any pertinent information you may need for your analysis/interpretation??

    So, I'm curious to know your interpretation of this NP on this particular type of crit course...deflation? be my guest...
     
  14. tommyrod74

    tommyrod74 New Member

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    I'm not Alex, but I'd guess... it's only a 30 minute effort? Any chance you could have that kind of NP in a 1-hour crit? Doesn't the "hard race" need to be ~1 hour in duration to be a reasonable estimate of FTP?


     
  15. tonyzackery

    tonyzackery Well-Known Member

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    ^^^Thanks for trying to be helpful, but...

    On a 20min effort, conventional "wisdom" says to subtract something like 5%. On a 30min effort, you subtract what percentage? For discussion sake, let's say 3%. So, 387 x .97 = 375. Still 35-40w higher than my FTP.

    As I've so valued Alex's opinions and always looked forward to his contributions over the years, perhaps he'll deflate my "inflated" interpretation...
     
  16. JibberJim

    JibberJim Member

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    Alex didn't actually say the NP was a true reflection of your FTP, just that the NP for the ride would be closer to your FTP than the AP of that ride, was it? ie was your AP for the ride 50 or so watts below your FTP?

    Personally I don't hold much importance to there being a single FTP - the functional part is too important and some folks will have a much higher FTP on an undulating power course than an iso-power one. I get a higher AP on an undulating course than I do in a flat one - partly I think it's because I will always change my position to more aero when I'm hitting 25mph on the flat, and partly because isopower just doesn't work well for me.

    If you want an FTP value for using it in a PMC - have specific ones to your position/nature of ride (so your 25mile TT derived one for flat TT rides, your 1 hour NP crit dervied one for your Crits, a typical undulating course one for your general riding. If you just want one to compare with your friends, pick your biggest or your smallest depending on if you want to under or overplay it.

    For me, my 25 mile TT bike position effort from a TT bike derived FTP is ~300watts (305 for 56)
    My flat riding Flat riding road bike position FTP is ~320 watts (from 10mile TT's and 1 hour flat TT efforts)
    My hilly crit riding FTP from 1 hour NP of hard sessions is ~340 watts (from 50-55 minute efforts in undulating roads)

    I could take any of those numbers as my FTP, but if I did, and if I used it to then set training zones I would be very much under or over training (I couldn't it 85% of my last derived FTP on my TT bike for example, or would ride around ultra easy on the hilly crit if I did it at my 25 mile TT derived FTP) And if I used a single number in the PMC that wasn't appropriate to the type of riding I was doing individual rides could be 20% under or over valued depending on their nature!
     
  17. tonyzackery

    tonyzackery Well-Known Member

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    ^^Preaching to the choir in most respects, but thanks for your input...I'm more interested in hearing Alex's interpretation of the information I provided. Hopefully he will provide his expert analysis, and if he needs additional info, he'll let me know...
     
  18. Alex Simmons

    Alex Simmons Member

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    1. I don't know if Saris software correctly calculates NP.

    2. Assuming it does, then WRT inspecting NP with a view to seeing if FTP could potentially be underestimated, then you'll need a race of about an hour. Even then it will be within 5% and NP will be closer to FTP than AP will be. Remember that one of the seven deadly is sins is "NP from a hard race of about an hour".

    3. 30-min crits are too short and you can definitely have an IF of > 1.05 from a 30-min crit. I have.

    4. It is possible to have an "NP buster" but they are exceptionally rare, when truly verified (validated FTP, validated power meter accuracy, validated NP calculation). I've seen one, maybe two from tens of thousands of files.

    5. 5% off the Average Power of a 20-min effort in most cases still overestimates FTP. I generally find FTP to be more like 5-10% less than best 20-min AP (92-93% of 20-min power is typical). 20-min Normalised Power wouldn't even be in the ball park if talking a hard surging race type effort and I wouldn't even attempt to place a ratio on 20-min NP to FTP.
     
  19. tonyzackery

    tonyzackery Well-Known Member

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    "Normalized power" - in essence, it is an estimate of the power that you could have maintained for the same physiological "cost" if your power output had been perfectly constant (e.g., as on a stationary cycle ergometer), rather than variable (thank you Dr. Coggan).

    Appreciate the confirmation Alex that my interpretation of what NP was telling me after that race - it was hard and above my FTP (IF > 1.0) - wasn't inflated/img/vbsmilies/smilies/cool.gif...That's all I took from that race on this particular course, and that's all really I use NP for.

    Truth be told, I don't follow these numbers too closely - don't use PMC, WKO, Training Peaks or any of those other programs. My exact FTP? I couldn't care less due to the fact, as previously mentioned, it's not a static number as so many may want to believe. Different courses, varying weather conditions, different nutritional status, different bike positions, different day, different hour of day, different mood, different color socks, etc...all coordinate to ensure that FTP falls, I would guess, within a range of 25w. Furthermore, why would I be a "slave" to an 'hour power' number when 95% of my races are < 1hr?

    I like having the data and use it (1hr FTP) in a general sense to set-up my intervals and track TSS (via Power Agent), but do I really care of NP>FTP<Average Power for a given race? Nope, not really...those numbers basically are simply confirmation of what I already know from my perceived exertion...

    Power numbers are fun and a worthwhile piece of information in setting up a training program, but IMO folks can get carried away and caught up with the details in these numbers. Our physiology is just not that precise from day-to-day, variances are too great for a person to say "my FTP is X" and then plug in that number to a program...Different strokes for different folks, but my training has become much more simplified as I learn more - not the other way around...
     
  20. Alex Simmons

    Alex Simmons Member

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    Yep, sounds like NP is reflecting what you felt - it was very hard.

    Pithy Power Proverb: "If it feels hard, it is hard." - Andy Coggan

    For the record, I'm not advocating analysis paralysis for anyone. The depths of analysis that one might go into depends on each individual circumstance. Whether or not one needs FTP, NP and the application of an impulse response model based on those numbers is up to them or their coach.
     
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