I ❤️CARBS! (and so should you!)

[trpnhntr]

Here’s my zone breakdown for the last few weeks for context. During weeks 14 and 15 below I did 2 threshold workouts, 1 sweet spot, and 3 endurance. I added between 30-60 minutes of endurance to the end of every workout

This week isn’t quite finished - in an hour or so I will be doing this

Its first thing in the morning - so I won’t eat before. I’ll have a gel during the warm-up, a gel before the first set, a gel before the second set, and 100 calories of jelly beans before the third set. I will then have a banana and some strawberries during the extended cooldown in zone 2. Will total around 730 calories during the 2.75 hours I intend to ride, but with the intent of letting my stores get a little low during the last endurance area

Edit: This is what this ended up looking like in practice. I ended up extending the warmup since I wasn’t feeling only 10 minutes of warmup before diving into that workload

[bbarrera]

@trpnhntr

This week isn’t quite finished - in an hour or so I will be doing this

It got hot this week and that means allergies are kicking my ass and I wake up “allergy sick” - best case I’ll get an easy two hours in this afternoon. That makes this week a non-starter for the beginning of another 4-week block, like those 2 weeks in March. Big sigh, at least I’m now at a point where most workouts are above 1000kJ…

[admigo]

I wrote this on the other malto thread. Would be interested in some ideas…

Maltodextrin or Glucose for fueling?

Puzzling for me are the isotonic dilution rates. I understand Maltodextrin requires 3.3ml/g and Fructose 26ml/g in order to be isotonic. If that’s true then for 80g of 2:1 glucose to fructose you’d need 864ml of water. Correct? So what dilution is really being aimed for here?

Any thoughts?

[DazzaW1]

@Captain_Doughnutman

g you’ve topped up glycogen levels.

I think this’ll be key you have to eat well the day before, consuming enough healthy low GI carbs to feed and repair your muscles otherwise you’ll run at a loss and in that is a slippery slope. The Grand tour riders in Europe are a classic example of on going depletion leading to poorer performances later in the 21 days.

[magnanienrico]

Hi everyone!

I have tried commercial products (e.g., Maurten, GUs, …), honey, maple syrup, and sugar water… I think they work really well to decrease RPE and fuel the workput/race. However I really don’t like to have very processed food, or very simple sugars in excess or on a daily basis (the other day I looked at the bowl with 150g of white sugar before putting it in the bottle… it is a LOT).

For training/everyday rides above 1hr, why don’t time other carbs based on the relative digestion timing?

For example, if rice takes 45min, I eat some rice bars at the start of the workout and they should kick in in the 2nd hour. Or, if I eat sweet potatoes maybe 1h30m before, I should obtain the same effect…

What do you all think?

I did not find a good source of “digestion time” for different food online… still looking.

Thanks!

[wysbf2]

You’re effectively looking for a list of Glycaemic Index values … e.g. like this tool: http://www.glycemicindex.com/foodSearch.php
( GI is based on a reference value of 100 for glucose, and measures rise in blood glucose 2 hours after eating)

[shawrx]

Your post is so big its even got its own T-shirt!

I Love Carbs Tee

[Simo429]

Runners how are you fuelling? Maurten gels are expensive but other gels seem worthless when you look at how many carbs they have

[rawjunk]

Is there a reason why highly branched cyclic dextrin is rarely used in endurance sports?

[matthew.weigel]

It’s a little more complicated than that, and you’re probably looking at needing more water to process more carbs.

Here’s what Tailwind has to say:

However, the anticipated stomach emptying benefits have not materialized in practice because the chains begin to break on contact with saliva, so osmolarity increases before getting to the stomach. Then, in the small intestine, the remaining linked molecules must be broken apart in the small intestine before they can be absorbed.

I was listening to a presentation on nutrition and race fueling from some local coaches recently, and they brought up the same issue: even if you put enough carbs down your throat, you probably need to drink more water than you thought to digest it all. This gets you to trying to balance the amount of liquid you can empty, so that you’re not sloshing around, too. I think improving on this is Maurten’s claim to innovation.

My general thought is that I can expect my gut to process the appropriate volume of carbs and water faster and better if I practice it, and doing that on the trainer (not too hot, not too sloshy, no worries about balance, etc.) has worked pretty well for me so far.

[cwiggum]

And most discussions on here always talk about this subject in terms of the fastest ways to get carbs absorbed. What always gets overlooked is hydration. How you get max carb intake without sacrificing hydration does require more water vs just looking at it from carb perspective. And you hit on this

We hear alot about stomach emptying rate, which maltodextrin has an advantage . Dont hear much in this forum about small intestine absorption rate, which maltodextrin has no advantage AFAIK. Which is the real limiter? My feelings has always been that it’s the intestines, as long as your only throwing simple sugars in your tummy.

[admigo]

Thanks for the insights. I knew in reality it was not as simple as a isotonic osmo calculation, and I guess this is where Maurten’s claim to fame is. I used to work in colloidal science, and I know physical chemistry is complex, but what got me thinking is that I know too that when you have the right concoction it’s pretty simple from there out in. Hydrogel formulations are impressive, you can encapsulate these things into blob emulsions until it reaches the target point. Still, on the other hand, I knew some cowboys who just mixed some crap together and got lucky.

I think the real complexity is what you all alluded too is the breakdown of sugars at which point. The classic example is chewing bread for long enough until apparently you end up with a harribo. I would say now my gut is relatively well trained for sugars. I had some issues, but it is significantly better. I am looking to avoid being dependent on high cost products though - Maurtens is making something that works for many, but their marketing is also a well-driven machine and us athletes here I would argue in many cases tend to game it too much, and a simple case of necking some fuel (malto + water + additional component) is most likely enough.

Now where did I put my larger bottles?

[cwiggum]

@redlude97

hydrolysis takes place at a much faster rate than the rate of absorption across the gut barriers via transporters

I really have appreciated our past discussions on this topic and your knowledge. But everytime we have this discussion, it’s always about the carb. Which was the point of my previous post. We talk about glucose transporters and gastric emptying. But our discussion never addresses hydration, which my understanding is that it is effected by the caloric load of your small intestine. The more calories in the intestines, you have to match that with more water intake or it will draw water from your blood. I hope I explained that clearly as I’m interested in your thoughts on how caloric load effects hydration.

[bobw]

I’ve held off using either gels or sports drinks (commercial or home made) during workouts until today.

Did Huxley+1 which is a whole load of type two fun! I think I prefer Mary Austin and Leconte

Experimented with a homemade sports drink of 3 tablespoons of sugar (about 40g) and a large pinch of salt in 750ml of water. Used that for the first fifty minutes or so then switched to plain water for the last twenty. Whether it made any difference I don’t know but the normalised power for each set, including the minute recoveries, was within 2W for all four sets. The third set felt particularly hard so I thought the last set was going to be a real struggle but I managed to hold on (with a bit of self-encouragement). So it’s possible that the drink did help.

My homemade concoction tasted pretty much the same as the commercial ones I’ve tried, well from memory as it’s probably five or six years since I’ve used one.

[Captain_Doughnutman]

@bobw

sugar (about 40g) and a large pinch of salt in 750ml of water…it’s possible that the drink did help.

The 40g of sug provided 20g of instant fuel (glucose); the 20g of fructose were still processing even after you got off the bike.

Hux +1 requires ~250g carbs; you should have had that much via stored muscle glycogen, ergo, you most likely didn’t need the sug. However, it probably reduced RPE, which is always beneficial esp. during the harder workouts.

On the other hand, when I first started chugging sugar water, I was using “anywhere from 75-100g/hr” – that was like rocket fuel and really reduced RPE, but most likely a very unnecessary intake for actual work completion (and proper diet).

[bobw]

I’m certainly not bonking on any of the workouts up to 90mins/2hrs so I’ve more than likely got enough storage (that’s my excuse and I’m sticking to it ).

As I noted the third set felt hard but the last set didn’t feel as hard as I thought it was going to be so possible that it took awhile for the sugar to hit. The intervals at sweet spot up to FTP certainly felt very easy but they were only a few minutes long. The next hard workout is Mount Alyeska+1 then Mount Major+2 and Geiger+1 so I’ll keep on with things and see what happens in particular regarding RPE.

Workouts like Huxley are atypical for my target events - they are more like Baxter, Baxter, Pettit, Baxter, Leconte, Baxter, … so being fat adapted, but not necessarily keto, and maybe fasted is preferable. I do need the top end but it’s a very small part of things and it’s mainly age related in order to keep muscle mass. Drinking that amount of sugar for 16hrs per day for several days on end wouldn’t be nice - my dentist moans at me as it is! Also I’m not used to sugary drinks of any sort, it’s at least two months since I last had any pop (soda), so the taste is unusual.

[cwiggum]

It is this passive process of moving water across the lumen that I am talking about. Haven’t made it all the way through the article, but some points so far.

While consumption of many beverages occurs for pleasure or from habit,6,15 the resultant intake of fluids will cause their water content to enter the body water pool following ingestion. How quickly this occurs is dependent on many factors, of which the 3 main elements are the rate of gastric emptying, the rate of intestinal absorption of the ingested beverage, and the speed at which the absorbed water enters the water pools.

Agreed on all 3 of those elements. It’s the intestinal absorption element that I am talking about.

The presence of nutrients such as carbohydrates, fats, and proteins in beverages not only supplies energy, it also affects the solutions’ organoleptic properties and their rate of absorption in the small intestine.

I think we can agree we are not talking about fats and proteins in this discussion because we are ingesting only carbs with the goal of quick absorption. In the 2nd sentence, it is this “effecting” of absorption of water, specifically, that I am talking about.

It is thought that the rate of gastric emptying is the main limiting factor in the assimilation of ingested fluids.8 Because of the complexity of the mechanisms that control the gastric emptying process, it is not surprising that there is considerable interindividual variation in emptying rates.24,28,29,31 However, most individuals do appear to be relatively consistent in the rate at which they empty the same solution on different occasions.27–29, Many factors have been shown to influence the rate of gastric emptying of solutions.
Apart from the receptors that respond to the volume of the stomach,32 the majority of receptors that regulate gastric emptying are found in the duodenum33,34 and ileum.35 These receptors appear to function primarily by initiating neural and hormonal responses that modify gastric and duodenal muscular tone and the frequency of contraction. The position of the receptors in the small intestine suggests their main function is to inhibit gastric emptying and, thus, prevent the absorptive capacity of the intestine from being overwhelmed.

So if the absorption in the small intestine can limit gastric emptying, then it could be said it is more important than gastric emptying. Part of the gastric emptying limitation seems to be in place to keep the small intestines from getting overloaded.

Then there is “Table 1” which you have posted.

• Increased volume in stomach increases the rate of emptying. This goes with what I am saying about also increasing the water volume when increasing your caloric intake.

• High energy density of beverages reduces emptying rates. Also coincides with what I am saying. If you are increasing the energy in your drink, you need to match it with more water.

• High osmolality of beverages slows emptying rates. Same as I said above for energy density.

Surprisingly, the rate of gastric emptying is regulated such that approximately isoenergetic amounts of carbohydrates, proteins, fats, and alcohol 34,42,43 are delivered into the duodenum. It is now well recognized that solutions with a carbohydrate content of ≤2.5% empty from the stomach at essentially the same rate as that of equal volumes of water,47 and most studies have shown that carbohydrate levels ≥6% unequivocally slow emptying.48 Even glucose concentrations of 4%–5% produce small but significant slowing of gastric emptying.

So again if we are trying to get this through the stomach and intestines as quick as possible, we need to keep the concentration low. Therefore adding carbs to your rate of ingestions needs to be matched with water.

While it is clear that osmolality is a major controlling factor for solutions with no nutrient content, this is not the case for fluids that contain energy.51 Substitution of glucose polymers for glucose monomer can be used to reduce the osmolality of the solution while maintaining the total carbohydrate content. Several studies have examined the effect of replacing glucose monomer with polymers on gastric emptying, but the findings are not consistent. Most investigations have found little or no difference in gastric emptying of isoenergetic solutions of glucose monomers compared with glucose polymers, despite the often large differences in osmolality. This lack of difference implies that hydrolysis of the polymers occurs before reaching the small intestinal osmoreceptors. Therefore, the osmolality of the isoenergetic solutions are, in fact, equal at the point at which they come in contact with the regulating osmoreceptors.

That paragraph doesn’t sound that great for maltodextrins claim to fame.

And somehow you pulled me back into the gastric emptying discussion again . But I did learn water is very important for gastric emptying as well. My main concern has actually been about not decreasing hydration by effecting absorption of water in the small intestine.

The current concept of net water movement across the intestinal wall is that water flux is passive and dependent on osmotic, hydrostatic, and filtration pressures. Water absorption from the intestine is considered to be a passive consequence of solute absorption, resulting from local osmotic gradients that promote net uptake of water from the lumen across the intestinal mucosa.

It is because of this passive nature of water absorption that I bring this up. Although glucose uptake has an active process in place, we have to set ourselves up for success in terms of water for us to hydrate properly. A caloric dense intestines isn’t going to passively absorb water the same as one with a lower density. The active pathways for glucose are 1 way. The passive pathways for water are 2 ways. It’s my understanding that you can pull water from the blood across the lumen into the intestines, essentially dehydrating you.

• Gastric emptying rate: Also supports that more water will speed up this process

• Osmolality: Water absorption rates are faster with a solution that is less dense, hence more water

• Carb content: So some water gets transported along with glucose through active mechanisms, which I already knew. Maltodextrins are helpful here as they create low osmolality. But at this point wouldn’t it already be broken down to glucose? And the trend here is saying lower osmolality is better, hence more water.

Well, that’s as far as I have made it so far. Hopefully my formatting pans out as I’m a novice at this. Great link btw!

But in summary, what I am saying is this. If I have a water bottle containing say 150 calories of simple sugars and I normally drink 1 bottle an hour. If I want to double my hourly caloric intake, I should drink 2 bottles of the same concentration instead of cramming more calories into 1 bottle. It’s the hydration side of things I’m more concerned with.

[Scapewalker]

Have you guys tried eating dates and bananas only during 2-3h rides?

[Captain_Doughnutman]

There is a lot of fructose in dates, not a great choice of fuel for a 2-3hr duration. You’d need to scarf down a dozen dates just to get ~20g glucose. Plus all the water to wash those down.

Bananas have to be eaten in a very ripe/black stage to get the greatest amount of sugar (vs starch). Even then it can still be ~40% fructose. For a medium banana, you’ll get ~10g of glucose…and a ziplock full of Wet Wipes.

Save the fistful of dates and smooshy banana for those longer rides.

[Beneluxrider]

So what would be some natural good sources then? I have good experiences with dates on 2-3 hour rides, especially if taken at the beginning of such a ride.