i think for me it has more to do with the looming bar exam than anything else.  there's not enough intensity in my mind, body, and soul to study for it with the required energy all day long, then still have the winner's thirst needed to dig deep and answer to the physical demands of a bike race.  i'll be back in august!

Tito, I think the conventional wisdom here is good. If I recall correctly, perpetuem is pretty light on the carbs/sugars? And if that is the case, you certainly have a better shot at not getting GI upset than if you tried something like Accelerade for the first time. Still, I'd stick with what your body knows best at this point, and just focus on making sure you are taking in some sugars/carbs every hour or so on the bike.

For me and many others, that's the hard thing...remembering to eat, keep those coals hot and fiery before they flame out completely.

@Tito. I prefer beeretuem, while it does cause frequent urination and belching (the clearly heard kind), I can drink pints and pints of it. When it's really hot I revert to drinking more of it because it makes me thirsty.

I think perpeteum or however u spell it is somewhat easy to adapt to but then again that may just be me, I throw a lot of curveballs at my stomach.
I essentially only use it for races, I don't like to train with it because its expensive and training is never as demanding as racing so I like having that buffer.

alyoshas said:

 but then again that may just be me, I throw a lot of curveballs at my stomach

That cheese looks good

Mmm. Camembert....

Paris-Camenbert?

Jules said:

More on Lactate as fuel

http://www.runnersworld.com/race-training/three-reasons-to-love-lactate

This whole business with using lactate as fuel continues to bother me. I read the article in the J. Applied Physiol. referred to in the above (crappy) article. There is interesting data about rates of lactate appearance and disposal as well as something called the metabolic clearance rate (MCR). The latter is the key to this idea of using lactate as fuel. The main conclusion of the article is that the lactate threshold represents the point where your body is unable to dispose of lactate fast enough. There is a mysterious fall in the MCR at the threshold, so the whole system works better at 10% below threshold - even if you pump exogenous lactate into the bloodstream via a catheter. Speculation about the blood being shunted away from the liver and muscle transport proteins not working as well (all speculation).

@dstokes - thanks, you just made my workouts 10% easier.

thanks @dstokes for reminding me that i know nothing

maybe they're not at a quintana/froome style threshold...where you need O2 afterwards

If there is plenty of O2 available, then why is the lactate made in the first place?

The conventional way of determining lactate threshold is to plot blood lactate levels vs. power output (see below). The inflection point of the curve is deemed threshold. And the conventional interpretation is that glycolysis (breakdown of glucose) takes you to pyruvate without having to use any O2. If you then have O2 available, you enter the Krebs cycle to produce a bucket load more ATP. If you don't have O2 available, then you make lactate and call it a day (or call it fermentation). So the simplest way to look at this is that as you increase your power, you have decreased ability to satisfy O2 demands of your muscles and you produce an increased amount of lactate. When you hit the threshold, you simply cannot keep up.

Back to gluconeogenesis. After having slept on this idea, I have the following thought. The article said that gluconeogenesis occurs mostly in the liver. That is kind of cool. It means that as your muscles are producing lactate (due to O2 debt) your liver can take in that lactate and convert it back into glucose, which can then recirculate to your muscle for reuse. OK, so your liver is now running the system backwards, using its ATP to make glucose from lactate, but you may have ATP to spare in your liver, which is just sitting around  not doing anything while your muscles are screaming for help. Liver also stores plenty of glycogen, which is a source of blood glucose as well as a source for the ATP to reconvert the lactate. I think the article said that 10-20% of lactate is disposed of in this manner, which if nothing else is a way to lower blood lactate and maintain a reasonable pH (prevent acidosis).

Owen's is strangely silent in this debate. He should know all about this by now.

  

Jules said:

@Stokes is O2 really that hard to come by at threshold?  I know the elites are now training with pulse oximiters for their V02 max efforts, but my understanding has been that even at threshold there was plenty of O2 available.

@dstokes - thanks for making my liver training 10% harder.

@ Jules CX training already? I guess all road and no play...

I am not sure what this means but I've have Willoughby Wallaby Woo stuck in my head for weeks now. 

For the coaches out there - does this make any sense to you to quote this in Watts or Watts/kg?

first day back on the bike today after 10 days of forced abstinence.  admittedly i did struggle a little to even do 30 mins' tempo as part of a 90-min session, but in terms of the positive mental effects (i.e. i was raring to get back on the bike and go fast), the rest was pure gold.

Jules said:

For the coaches out there - does this make any sense to you to quote this in Watts or Watts/kg?

Including weight seems to imply that it is a factor in how much power drops off over time - and that sounds odd to me. (Emphasis below mine)

"It shows, for example, a significant and normal power reduction of 60 watts (0.88 w/kg) between twenty and sixty minutes efforts. On average an athlete loses fifty watts in this time interval. The RPP that Froome has over two years does not seem to show any abnormality in its fundamental structure. In other words, the power data of the last two years is consistent with the profile that it represents. The performances he made on Ax 3 Domaines and Ventoux were to be expected in view of his PPR. During the last two years, his profile has not changed. It appears that the potential that he has today is similar to the one he had in 2011."

It doesn't make sense to me because, among other things, it lacks context. What kind of efforts are we considering here? Threshold? Then no, no way should you be losing 50 watts between a 20-minute effort vs a 60 minute effort. 30 watts maybe. Not 50.

At the moment I can't think of another context in which a 20 minute effort could be compared, in kind, to a 60-minute effort. Tempo? No, because then you should lose even less watts. Endurance? Certainly not. VO2? Hell no.

It's the kind of useless "expert analysis" out there that reminds me of the random power numbers, not attributed to anyone in particular that NBC would post on some graphic on their coverage of the tour. As if, "the field" itself was some monolithic rider who generated x number of watts over the last 10k. It was bizarre.

Well, if your threshold is 400W, then you might expect to lose 50. At our level, 30 or less may more reasonable. In that sense, it makes more sense to talk about % threshold.

@Jeff No data, just seems to work well for me — just this on its own for racing — makes me feel more even throughout. Although the first couple of times I tried it, it gave me a headache... so test before you race Battenkill.

I use Skratch too and like it. It has a pretty subtle taste and easy on the stomach for me. 

It's too early to know for sure, but so far, I'm really digging my late summer racing schedule of Saturday track racing, Sunday MTB racing. I think it's going to prep me for cyclocross season very well.