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

Originally Posted by nmcgann

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

Originally Posted by nmcgann

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.

Originally Posted by rmur17

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 ....

Originally Posted by Steve_B

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.

Originally Posted by nmcgann

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

Originally Posted by Alex Simmons

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.

Originally Posted by Steve_B

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.

Originally Posted by nmcgann

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

Originally Posted by Squint

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.