Power problem on road, but not on turbo - help!

Discussion in 'Power Training' started by nmcgann, Apr 24, 2008.

  1. nmcgann

    nmcgann New Member

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    I'm struggling with an incredibly frustrating power drop-off problem at the moment when racing (TTs in the UK) so I thought I'd ask the board for opinions.

    The background is I did quite a bit of L2 (4h rides) and L3 (2h rides) work on the road over the winter, but have done all my L4/SS/L5 on the turbo. I've been averaging 8-9h/week training over the winter. I recently got a powertap so I can see what kind of powers I've been doing and the L3 stuff is around 250W, the 2x20s at 285W-300W and the L5 5min intervals at approx 315-325W. My HRs are all consistent with the power levels and all looks good - in theory.

    So, I get out on the road to start the TT season and I am really struggling to reproduce the powers that I am routinely doing on the turbo. The usual pattern is that the first 5-6min is fine, I'm hitting 290-300W easily and my HR is rising nicely into my racing range and I'm feeling good and strong (I've been using the powertap to stop me going off too hard). Then my power just drops off to L3 levels and I simply can't pedal hard enough to raise it again, my legs just can't exert enough force. My cadence also drops markedly and if I drop a gear and try and spin faster I just go slower, so I end up doing low cadences to try and squeeze out what little speed I can. This has been going on all month, so it's not a one-off. I've not been ill all winter either, so I don't think it is a viral thing.

    Has any one seen anything like this before? Any suggestions? (my coach hasn't been able to come up with anything yet)

    Neil
     
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  2. rmur17

    rmur17 New Member

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    1. Your indoor power has still been good during this period?
    2. How does your turbo position compare to that on your TT bike?
    3. Same PM for both your indoor and outdoor work? Being careful to zero it before each w/o and race?
    4. How would you characterize the terrain over which you TT?
    all for now ....
     
  3. Steve_B

    Steve_B New Member

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    Has your diet changed in the past month or two and are you getting as much carbohydrate as you used to in the past, especially right before workouts?

    Do you have this problem if you ride L2 or L3 for the same duration, that is power doesn't drop there?

    It could very well be something medical. You could talk to your doctor and get a blood test.
     
  4. nmcgann

    nmcgann New Member

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    1. Yes.
    2. Same bike, but tend not to use the aerobars as much on the turbo.
    3. Yes.
    4. "Sporting" (the kind where the best club riders do 22m times)

    Neil
     
  5. nmcgann

    nmcgann New Member

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    Diet has always been similar since I've been TTing. I lost a load of weight the winter before last by cycling (just before I started racing) and have been eating the same diet ever since. I have wondered if I am eating enough carbs, but I am paranoid about gaining weight again. I'm never hungry when I race though, I have a carb snack a couple of hours before.

    I can do L2 and L3 fine - I did a 2 hour L3 ride last Sunday after one of my disappointing race efforts and maintained 250W+ no problem.

    If it's something medical then it's a long-standing condition since every TT I've done has had a similar pattern - it's only in the last few months that I've had a powertap and can clearly see what is going on. HR doesn't always track the clear drop off in power on 10mile races, although when I do longer TTs (25s) I often struggle to keep my HR up toward the end (it drops to L3 levels) so that is indicating something is wrong too.

    Neil
     
  6. Squint

    Squint New Member

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    Last winter, I did all my SST, L4, and L5 indoors on the erg. I've experienced very similar symptoms riding L3-L4 outside. I think the stochastic nature of riding outside results in neuromuscular or other adaptations that are lost when doing the majority of your hard rides indoors.

    I don't understand it completely and I haven't fixed it completely but I've made good progress. What I've done is lowered cadence during L3/4 indoors from 95-100 to 80-90 rpm. The latter is more representative of the cadences I ride outside on long climbs. The other thing was being forced to ride at low cadence/high force on those long climbs due to strong headwinds. Power outside is much closer to indoor power now and the feeling of not being able to generate the force required to turn over the pedals has been replaced by a much more "powerful" sensation.
     
  7. Alex Simmons

    Alex Simmons Member

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    I'd be looking into this. By not riding in the TT position very often, I'm not surprised that power drops when you do.
     
  8. Steve_B

    Steve_B New Member

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    Yeah, generally my power in my very aggressive TT position is 10-20 W lower than on my traditional road position and the discrepancy improves as I get reacquainted with the TT position every year.

    Do this: Go do a similar workout to the one that causes you difficulty on a traditional road bike. Even if you don't have a power meter on that bike, it seems like you could tell if the issue exists there too. If you don't have the problem on the road position, you might have your answer right there.
     
  9. swampy1970

    swampy1970 Well-Known Member

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    I used to find that by training in my time trial position that I'd be OK for riding hard on both the TT and road bike - but if I trained just on the road bike then I'd be up shit creek without a paddle when it came to going hard on the TT bike for a while.

    That said, my TT bike was made from 531 as a test mule, so I didn't worry too much about throwing it into the dirt and slush of winter roads and coating in sweat (the sweat that the big towel missed) from riding on the trainer.... If you have some fancy carbon bike for "testing" on then you may think twice about doing this.

    As the usual internet cop-out goes - YMMV. ;)
     
  10. Overhill

    Overhill New Member

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    nmcgann, I have the same experience, especially this spring after a long cold winter and very few outside rides. I think Squint is probably right in his analysis. Also, on the trainer, with the TT bike, I can do much better power sitting up than in the TT position. I am trying to do the hard efforrts in TT position. Good inquiry.
     
  11. Squint

    Squint New Member

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    After doing more reading and some quiet contemplation, I think it's more than simply a neuromuscular issue.

    If you look at a histogram of torque from indoor and outdoor rides at the same power, you'll probably notice that the outdoor ride has a wider "spread." There is a variety of torque values resulting from a combination of the stochastic nature of outdoor riding and a variety of cadences.

    Since force is a major determinant of muscle fiber recruitment and riding indoors results in a much more constant power and cadence (and hence torque/force), less fibers will be recruited. And of course, fibers have to be recruited in order to be trained so a lot of indoor training will concentrate all the training adaptations in a small population of fibers.

    So...what to do? I think if you do enough outdoor riding once it warms up, you'll eventually train the higher activation threshold fibers enough that your outdoor power will equal your indoor power. Of course, it would be best to try to train those fibers that detrained over the winter while maintaining fitness you built up in your lower activation threshold (slower twitch) fibers. This could possibly result in a higher outdoor and indoor FTP than your current indoor FTP since the sum of your muscle fibers' oxidative capacity would be greater.

    The recommendations I've come across for training higher activation threshold fibers are microintervals, conventional L5/6 intervals, and pre-fatiguing the slower twitch fibers. I think microintervals might be the best method but it might be hard to do them properly w/o a programmable ergometer. They are what I'm doing now and hopefully will see discernible results within the next few weeks.

    Sources: AC's old wattage posts, various studies.
     
  12. frost

    frost New Member

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    I had quite similar experiences starting this spring and looking at the indoor/outdoor power files came to more or less the same conclusions as you above. Even in a fairly flat route the power varies easily between 150 and 750 watts (well as a new power meter user I could use some time to work with the pacing) while on the trainer it's quite easy to keep within 10 watts on a 300-330w average 20min effort. While those 750 peaks being so short that they do not have remarkable effect on normalized power comparing to average power (and therefore also to metabolic prosesses at least in principle) clearly they take the best out of legs.

    The good news is that, (as the discussion in wattage posts imply if I remember right) the adaptation to outdoor riding indeed seems to be very quick. Even without specific targeting. Just simply riding outdoors is specific enough for that.
     
  13. ric_stern/RST

    ric_stern/RST New Member

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    just as a thought: when i was fit, i could generate ~15% more power indoors (on a turbo) compared to a flattish road outdoors. On a long climb i could generate the same power as indoors.

    Ric
     
  14. frost

    frost New Member

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    It would be very interesting to hear similar comparisions (turbo/bike) from indoor track (even in an indoor track the power doesn't stay constant).
     
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