Much about muscle metabolism is clearly understood. Glucose is converted to ATP and other substrates to produce "energy".

That being known, the limiting factors become the ability to deliver and maintain glucose stores in the areas needed by muscles to perform work.

Of course, so many other factors influence glucose transport, enviroment, intensity of exercise, mechanics of exercise etc, that this will always be the "crux" of the matter.

So my question is, how do you predict glucose needs in a big ride if you do not know the"pace" or intensity you will be maintaining before hand? When does lack of fat or protein ingested become a limiting factor?

First, keep in mind that glucose is NOT converted to ATP. Glucose is broken down to water, plus carbon dioxide. There is another process the body uses from taking one of the ions of glucose and using it to drive another reaction of ADP + phosphate= ATP. How much ATP is produced is dependent on if the process is done during anaerobic efforts or aerobic efforts.

See the post I did recently about the Krebs cycle for a better understanding... I greatly simplified this explanation I gave above for the sake of time. The thread with the better explanation: https://bikeforums.net/showthread.php?s=&threadid=20602

If you're planning for a long endurance ride, the best thing you can do is carbo load the night before, then bring some snackies on the trip that will convert energy over several hours upon eating, like a powerbar, or a banana.

If you're just planning for a shorter endurance ride, consider eating a light carbo meal before leaving (like a half an hour so you can fully digest the meal and not ride on a full stomach) and carry a snackie along just in case. You never know if you consumed enough carbs!

If you've got a high intensity ride you're planning, best to eat about half an hour before leaving- something high carb. Then you'll probably want something the body can quickly use for a glucose source in case you start to feel like you're bonking. In this case, something with simple sugars is best- gatorade and Gu are the first things that come to mind.

Proteins have little to do with this- it's not entirely useless, but when you're needing a quick energy source, it's easier for the body to break down say a bananna for energy than a steak! So for your optimal performance, choose that bananna over the steak anyday as your quickie energy source!

Fats are a bit different. I'm not sure what you're meaning by lack of fats, except maybe foods high in fat? Or lack of fats in the diet?

When eating for performance, just think carbs- simple (gels and gatorade) vs. complex (banannas and energy bars) and consider which situation you'll be riding under, then eat for your optimal performance!

Koffee

<<<<<Glucose is converted to ATP and other substrates >>>>>

What part about other "substrates" don't you understand? Yes, my statements are technically inaccurate.

However, I would suppose, the answer is: Just continue to "top off" your energy stores during a ride and hope the slight "overload" isn't detrimental to performance.

The gist of my question was to solicit comments about intensity and length of exercise in realtionship to supplying differing blends or ratio of carbohydrates and or fat, protein, bulk etc.

Many athletes are turning to energy replacement formulations containing 20-25% percent protein. These athletes are using these products from the start of a given event.

My own suspicion, is that the best performance would be had by delaying or skipping the use of protein/laden products for events less than 12 hours.
However, I still wonder if in fact, with less intensity, that the protein containing product, could be beneficial to future performance if used from the start of an event.

Please excuse my over simplification, I have neither the time nor inclination to frame and describe my hypothesis in a technical manner.

Thank you for all your wonderful posts, you are truly a valuable resource.

IMO you should always start with your glycogen carb stores topped up and then you are good for up to a few hours without refueling depending on intensity.From there my refueling is determined by intensity and duration.For quick bursts of high intensity I will go with mostly high glycemic refined carbs(honey etc.) and more sustained high intensity still mostly carbs but mix in some easily digested lower glycemic less refined simple carbs
(dried apricots,other fruit +honey etc.).For lower intensity I will go with a combination of lower glycemic more complex carbs plus fat (and a small/moderate amount of protein)with the % fat increasing as the intensity decreases(dried apricots,complex carb based energy bar +pitaschios,dried coconut etc.).When I am in a range where I'm utilizing a large percentage of fat for fuel I find including some fat intake for fuel helps .Keep in mind the protein,fat and complex /low glycemic carb choices need to be made with what you can easily digest in mind . As the duration of the lower intensity increases I may go back towards more refined sources of the above focusing on whatever I can digest.
So I guess I increase the protein somewhat as the intensity decreases and the duration increases but my objectives include avoiding muscle loss not just pure performance.Still I generally save the high protein intake for the post exercise recovery phase.

It is better to be technical and detailed in your posts so that we understand what it is you're asking for and don't waste half an hour out of our valuable time explaining something that you're not interested in.

My apologies. I had no idea that you were headed in that direction.

I'm sure someone out there can answer your question better.

Koffee Brown

My comments on what's already been said:
I have limited experience with adding protein to the on-the-bike regimen. I bought a can of Accelerade and used it for various intensity rides. I never *noticed* any benefit. For shorter, intense efforts, I felt it was worse than a carb-only beverage. I also tried it in a plenty difficult timed century with ~10,000 ft of climbing. By the end of the event, my kidneys hurt. Never had that happen before, and I don't know if it's related. Thanks anyhow... I was hurting enough! I'll stick to carbs. For 12 hour events, I dunno. Try it, see what you think.

As far as prep, RWTD nailed it. Why would you do anything other than top up the stores? If it's prep for a special event, also taper and pay close attention to carbo loading, etc.

Finally, gotta disagree with Koffee on the pre-ride meal. If it's gonna be hard at all, I eat 2-3 hours before. BTW, this meal always includes protein, usually in the form of 2 eggs. In fact, it's not too different from my normal breakfast. (It's the meal the afternoon or evening the day before that makes the big diff for me.) If the event is a major objective, and particularly hard, I'll eat a powerbar 1 hr before the start, and an energy Gel 20 minutes before. It comes down to this... once you're putting out, about 300 calories per hour is all yer gonna get. Choose 'em wisely.

One point I'd like to clarify is that a banana just harvested and green does start as mostly starch but as it ripens it converts to sugar so that a ripe yellow banana is mostly sugar in the form of sucrose.

RWTD,

sounds like you track carbos/glycemic index, the way I was trying to introduce a possible balance or scale torward the introduction of fat and or protein even before post event recovery....

The "top off" scenario I'm referring to is much like TDF riders fueling and drinking between any possible "maximal" efforts that may be presented.
(not pre-event total loading -- that's a given)

However, in a TT or iron-man like event, everything is kind of "metered In" so you don't end up with full bladder..or risking possible digestion-induced, "heavy legs"

In any case, I'm going to try some protein-containing products for end-of-ride use. Sometimes I already do, low-fat chocolate milk!

Haven't done the accelerade thing, was thinking, sustained energy....

Thanks for the comments.

The risk beyond the digestion problem is that if I eat too much protein while still exercizing I seem to go into the recovery phase while I'm still riding and want to stop and rest alot rather than continue on.Too much milk in particular seems to do that to me and the lactose can be a problem for some people but I think your taking the right approach to gradually try this too see how it affects you.Some of the protein powers that are included in the sports drinks/bars are very light and easily digested.In fact recently I have been using a fairly balanced as to nutrition bar called "Soy Advantage" that in addition to having 14 grams of sugar and 5grams of fiber out of 23 grams total carbs has 15 grams of protein(mainly soy isolate)and 5 grams of fat(palm oil/ground almonds) plus a variety of added V&M's .It is very easily digested and I seem to do well on it for quick as well as sustained energy.Only problem is I bought them cheaply at a store that keeps rotating their inventory so I don't know where to find them when I run out of my current supply lol.