Sorry I missed this inquiry!

Depends on your sweat rate as to how much sodium citrate you ought to add to the beverage.

Your carb math looks great. Right in line with our

Should be a sodium video coming out next week or the following!

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Thanks for getting back. I tried the mix with High 5 bit it didn't sit well.

There is a fairly new brand here in the UK called STYRKR, very similar to Maurten but 90g carb (2:1 malto to fructose mix), with 2g electroloyte and 3g of L glutamine. It's a very pleasant mix and cheaper than Maurten, but still pricey for anything other than key sessions and racing.

I bought bulk bags of the ingredients and now mix my own, although looking to up the fructose by 10g. I'd be interested to hear your thoughts on the addition of L glutamine.

This is all in a small bottle, 500ml of water.

Glutamine is generally pretty useless, and if it does what it's marketers say, which is often something like assisting with recovery via blocking inflammation (it probably doesn't), then it may actually HINDER your adaptations to the training you're doing. In general, things that help you "recover" better do so by reducing inflammation. Reducing inflammation tends to reduce adaptation to training, unfortunately! I wouldn't bother with the glutamine.

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I used the information in this thread in a surprisingly useful way.

I have type 1 diabetes and most of my fueling strategies revolve around controlling that. As a side benefit I end up fairly well hydrated and really well fueled. Drinks are Skratch, Cytomax, Gatorade, plus gels, bars, chews, even granola bars.

The unique problem I fight is unexpected low blood sugar within a workout. Treatment is easy, 20-30g of carbs quickly and within half an hour it’s fine. This is in addition to the typical fueling strategy for the workout. Gels have been my go-to but I get kind of tired of them and if I don’t need them then two gels have just been mashed up in my pocket for no good reason.

What I’ve done based on this thread is mix 15g Gatorade powder with 30 grams table sugar and 1/16 teaspoon sodium citrate in a gel flask half full of water. I backed off the sodium from 1/8tsp initially. In addition to whatever planned nutrition, I’ll bring this for unexpected lows. It goes down quickly (if a touch strong), absorbs quickly and if it’s not needed I’m only washing a few pennies of sugar down the drain.

Thanks for the great idea!

I think this problem is one area where your body still behaves like someone without T1D. Muscle sensitivity to carbs goes way up (as you've noticed, clearly) during exercise and if you're not on top of consistent fueling, even absent insulin dosing, you can have blood sugar lows. Glad the Gatorade+sugar approach has been handy :)

In case you want to resurrect low blood sugar faster, I suspect if you use a bit more water in that gel flask, you'll get faster absorption of the sugar into your bloodstream.

Peak fluid absorption rates tends to happen below 8% solution, but that's not the case for peak carb absorption rates. I don't know if optimal beverage concentration for peak carb absorption rates has been well studied yet, but I'd bet it somewhere above 8%. Probably 10-16% solution if I had to hazard a guess, but I could see it being higher in a well-hydrated state if exercise intensity is low.

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Just posting this here after a DM discussion with Dr Alex. I want to preface this by saying that he knows where I'm coming from and I'm not trying to undermine his work. I've been using his mix (dubbed Alacrity Mix) for a few months now and haven't had an issue with it. I've adapted to the 100g CHO/hour and everything is ticking along. I've started seeing a dietician and she asked about my intra-training mix. When I told her, this was her response and after asking Dr Alex for his opinion and insight into her response, we decided it best to post it here so Alex could respond and hopefully enlighten the rest of us.


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The reason I queried this is because of the following;

• Glucose (one of the forms of CHO you're taking on, approximately 52% of your current mix) maximally oxidises at 1g/min - which obviously then caps us out at 60g/hour. If this is 52% of our mix, this means we are roughly getting 52g/hour.
• To achieve higher CHO oxidation rates during exercise, we need to use multiple transportable forms of CHO. These limitations are based on intentional absorption of CHO. (Glucose needs the sodium-dependent transporter SGLT1 for absorption across the basolateral membrane of the intestinal lumen).
• This is achieved with the introduction of fructose (as it uses the GLUT5 transporter) which maximally oxidises at 0.6g/min (36g per hour). Fructose makes up the other 48% of our mix or 48g/hour.
• This puts us at a maximal oxidation possibility of 96g/hour, if 60g was coming from glucose/sucrose and 36g was coming from fructose.
  

Things to additionally note:

• The calculations I've done are based on the assumption that the "table sugar" i.e. sucrose is 50:50 glucose:fructose as accepted in the literature. I looked up the proportions of glucose:fructose in one container of gatorade and subbed those values in as well, see table at the end of the email.
• Intensity and time both play roles here too. At high intensity, any exercise <2.5 hours should only maximally need 60g/hour and can be kept to one type of CHO (i.e. glucose alone). Lower intensities require lower amounts of CHO. Once we get up past 2.5 hours (and if intensity is still high) that's when we drift up to 90g/hour.

So, what does all of this mean? Basically, unless you are a freak of nature, you can't possibly be absorbing all of that CHO per hour, which means we can do some tweaking. However, I am very aware of athlete's comfort zones, and not wanting to mess around too much outside of what they feel comfortable changing.


Gatorade Powder - 560g weight, 324g Glucose, 180g Fructose, 4080mg Sodium, 1800mg Potassium
Table Sugar - 2000g weight, 1000g Glucose, 1000g Fructose
Totals - 2560g weight, 1324g Glucose, 1180g Fructose, 4080mg Sodium, 1800mg Potassium

20g serving - 10g Glucose, 9g Fructose, 32mg Sodium, 14mg Potassium
52/46% split between Glucose and Fructose

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Fire away Dr Alex!

I've been following this thread for a bit. The science and info in here is super-interesting.

Assuming your gut can support the intake & your hydration level supports your sweat rate, I'm curious on what the downsides are to consuming say 90carbs (1:1 Glucose/Fructose) an hour when perhaps the math says you only need ~70 over the duration of your event?

Haven't these two bullet points been amply disproven in recent literature? I thought it was commonly accepted that maximum CHO intake was trainable and that there were lots of examples of 120+ g/hr (I've heard of up to 140 g/hr).

Alex,

How much does body weight/LBM affect the commonly referenced 90g carbs/hour metric? Surely this was based on a specific x grams/kg/hour in some study and subsequent literature?

I would imagine somebody 100kg would require more fuel, and also assume that person would be able to process more per hour?

I am 100kg/220lb and hover around 10% BF/~195lb LBM consistently, so wondering how much I should trust the “standard” numbers and if you are aware of any literature on this subject that would help make this a bit more secofic

Thanks!

Actually very little. Gut tolerances are minimally affected by body mass. Probably more affected by height, actually, due to larger organ size and greater absorption surface area. The aforementioned statement about height is mostly conjecture, but I'd place a small bet on it.

Certainly higher requirements, but less of a boost in absorption ability than I'd like, while I sit here at 94kg :)

I wouldn't trust the standard numbers at all. You're very likely to need >>90g/hr. The app I'm writing to handle all this will have an upper limit of 150g/hr, but I think it's truly a rare person who can absorb that amount. Much less rare is the ability to absorb 120-130g/hr on the bike.

Thanks![/quote]You're right that all the "standard" numbers have come from studies reporting only sample averages. Most of those studies have mean body weights of 65-85kg. I suspect higher lean body mass folks with years of high fuel intake rates historically, are capable of the greatest exogenous carb utilization during exercise. It'll probably be another 10-20yrs before that's well studied in the scientific literature because good luck finding a large group of college students (typical research subjects) who possess a very high LBM and also enjoy high volume endurance training. The time it takes to develop substantial muscle mass alone makes this a virtual impossibility.

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Excellent info - thank you v much for the detailed response. I am 6’6 so good point about organ size. Out of curiosity, have you seen any data on correlation between height and organ size?

One concern I have, and assume a number of other people have as well, is the demonization of sugar (for good reason in the standard American diet). I assume the negatives associated with this (inflammation, etc) are negated by the immediate use of the sugar as fuel, but curious if you have any thoughts on this topic?

Also assume this is why many supplement companies use alternative “complex” carbs.

Absolutely.

See end of video here regarding demonization of carbs.
https://www.youtube.com/watch?v=F-1JJqMblvc

Also see the more recent monosaccharides video, as I believe Michelle touched on it too.

The TLDR is: body, pancreas, and most organs, handle sugar vastly differently during exercise and there is strong evidence that it does not pose a long-term risk to health. (I'd be dead if it did)

Biggest risk = dental health. Chase with water.

One of my favorite canned texts to share with folks:
In the greatest irony of ironies (in my very small sport-nutritionist mind) many of the supplements that are principally maltodextrin are marketed as "complex" or "not sugar." Maltodextrin is viewed virtually identically as sugar by the pancreas, and other organs responsive to sugar because by the time it hits the blood stream (just as fast as pure sucrose, dextrose, or fructose) it is already fully broken down. The same thing is true for things like highly branched cyclic dextrin or just branched cyclic dextrin (HBCD & BCD). Body responds to it just like sugar. The primary reason any of them are used is actually to enhance the speed and ease of absorption in the gut (there are better ways and no it's not worth your money), but the irony there is that is precisely the purpose of plain sugar too!

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Hey BNothling, thanks for posting this here, and for your patience for my response. Wanted to do this one justice. Your dietitian is honestly better than average if I were to sample all dietitians for their prescriptive quality and rationale. Better than average even for CSSD's (sport dietitians), too, so I won't blame her for missing the mark in the very small ways that she may have here. Her recommendations are generally considered "best practices" by RD's in general. It's just that the body of ACEND and most RD's are not intimately familiar with endurance sport nutrition and the last 10 years of the most recent literature. So, honestly, kudos to her for being able to make very specific recommendations in the first place.

And, she's lightyears ahead of where I started when I made the plunge into endurance sport nutrition.

Fun anecdote: I once prescribed a male cyclist 75 grams of carbs, TOTAL for a 4-hour bike ride. He told me he was bonking after about 90-120minutes, and so I upped it to 125 grams of carbs. He reported still bonking after ~120-150 minutes, and having a miserable remainder of his 4-hr group ride. Just no power. Needless to say, he, rightly, did not renew his coaching package with me.

(this was circa ~2015, when I didn't have the first clue about endurance sports, and it was that utter coaching dumpster fire that compelled me to get out of weight room nutrient timing & glycogen repletion literature and into actual endurance fueling literature)

To whomever that was, if you ever read this, I'm truly sorry! Happy to credit you with 3 months of free nutrition coaching if ever you stumble into this thread, or lifetime free use of the app I'm writing.


I tell this anecdote to say to anyone learning to write endurance nutrition programs, or implement their own, I promise you already know more than I did when I started, and you're doing a great job.

Okay, let's dive in.

Not quite. Depending on who you ask, it's probably somewhere between ....


(EDIT)


60-72g/hr for pure glucose (as far as study averages go). FWIW: One poster on ST has reported consistently using 90g/hr of either pure maltodextrin or pure dextrose for all their carbs with no gut issues. The rate of total carb oxidation in the literature is more like 1.5-2.0g/min, IIRC, but with relatively higher incidences of GI distress above 60-70g/hr when consuming pure glucose.

Most importantly, to achieve 60g/hr oxidation of glucose, it requires >60g/hr intake because. If you're capable of oxidizing 100g/hr, total, it may actually take 120-130g/hr intake to cause such an exogenous sugar oxidation rate. This is true for all forms of sugar, independently, and in any combinations. Exogenous glucose oxidation rates exceeding 60g/hr (1g/min) are often found with sugar intakes ranging from 70-120g/hr.


TLDR: You must intake more than will be oxidized. Only way to get those numbers to be identical is to move ever lower towards 0g/hr intake rates.

(END EDIT)

Correct.


Correct.


Also correct.
This is probably just an inconsequential misuse of wording here, and I'm only pointing out the semantic error here for the edification of readers.

Trasporters don't oxidize. They transport. Oxidation happens later, in metabolism.


Her cited fructose max transport rate appears to be higher than I've seen reported by an RD before. Cool! Also a bit overly-specific, as is commonly taught in most RD education programs. (My wife is an RD and was remotely educated so I got to witness lots). Usually what is cited is 30g/hr. I'd say that 30-36g/hr is a good rule of thumb for max fructose trasport rate for that one transporter type: GLUT5.

GLUT2, however, is pretty neat. See my wife's recent video about monosaccharides, and watch the fructose section for why it matters. Short answer: more fructose intake hourly is possible when combined with glucose intake. The "36" number comes from fructose-only consumption studies.


Who knows exactly where it puts max oxidation potential, but I'd posit that if you're not having gut issues, you're transporting all of it peaceably through your GI tract.


She's a nerd. I love it.

BNothling's dietitian wrote:

I looked up the proportions of glucose:fructose in one container of gatorade and subbed those values in as well, see table at the end of the email.

Super nerd. Fantastic. This is above and beyond service from most sport dietitians. I'm curious what she found for those proportions. I've seen multiple ratios cited.

BNothling's dietitian wrote:

Intensity and time both play roles here too.

Correct.

BNothling's dietitian wrote:

At high intensity, any exercise <2.5 hours should only maximally need 60g/hour and can be kept to one type of CHO (i.e. glucose alone).

Depends on the person. Some people are going to get hypoglycemic as heck at 60g/hr. She's citing Jeukendrup's work, which has been cited most recently in position stands of the ISSN, which he co-authored. He's excellent, as has been his research. However, the recommendations that he puts forth are very generic, and have led to the under-fueling of probably 30-40% of athletes, to the extent that the believe their fitness is far lower than it actually is.


Yes, but intensities have to be VERY low to not merit fueling up to 90g/hr out in the 3-4hr realm, especially for a reasonably well-muscle or high-fitness person. Yes, higher fitness folks are usually capable of burning more fat, both absolutely, and relative to their total fuel oxidation, but they're also simply capable of burning more in general, including carbs. High muscle, high fitness, or both often demand >90g/hr unless we're at recovery intensities, once activity exceeds 2.5 hours.


Yes, and sometimes as high as 120-150g/hr is necessary and tolerable for large, muscular, or high-fitness athletes.


Not true.


The AVERAGE of the people studied in all the studies has shown that 90-120g/hr optimizes performance, in the sampled populations. Higher fitness, higher muscularity, or just higher carb burning ability genetically or via training adaptations, can absolutely drive those numbers up 20-50%. I'd posit the 40-50% range (ie. 140-150g/hr) is where you're getting into freak of nature status.


When a study claims to have found the "highest ever exogenous carb oxidation rates" what they mean is that the average of their study subjects produced that record rate, compared to the average of all other study's sample populations. Assuming normal distribution (or where mean ≅ median, roughly) that means literally half the subjects in that study experienced personally higher oxidation rates than the number that is statistically reportable in publication.


Research is especially lacking on larger endurance athletes with very high chronic fuel intake rates because it's never been broadly recommended. If there is anything at all truthful about the "train your gut" movement, I suspect we'll see even higher carb intake, absorption, and oxidation rates in the years to come as wider swaths of athletes start implementing >100g/hr periodically, when it matters.

@BNothling, I think this is a great opportunity for you to show her that you are indeed using all the carbs. She's allowing you to keep fueling at high rates. Might be fun to report back "hey, so I felt even better when I did 110g/hr." The same thing happened to me when I had an athlete say they'd tried 140g/hr for the first time and felt fantastic on a 5-hr ride. Opened my eyes to the magnitude of human variation that is possible.

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Alex,

I stumbled across this today - is this accurate? If so, seems maltodextrin would be preferred on the surface, esp for limited water carrying capacity (running, etc.), thoughts?

Fantastic question.

The math may be true. (I did not check)

The implications are not true.

Reason: osmolarity is not the primary determinant of gut tolerance, gastric emptying rate, or absorption rate for water, carbs, or sodium, or anything during exercise, for that matter.

Energy density and absolute energy intake rates and amounts are primary. Secondary is probably optimizing glucose:fructose ratio. Distant tertiary is osmolarity management. Presence of sodium with carbs probably matters more than keeping osmolarity low, too, tbh.

Yes, it may be true that the optimal glucose:fructose ratio is slightly shifted towards 2:1 from somewhere between 1:1 and 2:1 in cases of low water carriage capacity, for reasons of osmolarity reduction, but I bet if that is indeed true, it would be incredibly hard to discern the magnitude of such a shift. I'm really getting down in the theoretical weeds here. There would still be half a dozen other factors affecting things more than purely osmolarity management because when hydration ability is compromised, all other nuances of fueling strategy begin to matter progressively more.

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I don't know that I ever saw this reply but just stumbled into it. Apologies for redundancy if I indeed did reply earlier in this thread.

Correct, I'd call that a "no" for any modification of nutrition strategy towards attempts at increasing fat metabolism.

Reason: any changes are likely to be smaller in magnitude and impact than the negatives they cause (ie. decreased carb oxidation ability). Not to mention, lost opportunity to practice race fueling strategy, cause gut adaptation towards greater ease of race fuel implementation, increased RPE in training and reduced training recovery speed.

I won't ignore the argument that having high fat metabolism ability is critical for success in ultra-endurance performance.

I just posit that high fat oxidation ability shouldn't come to fruition, by way of nutritional modifications.

Rather, get good at burning fat by getting fitter and better at fat ox via training. This can and should be accomplished in the presence of very high carb fueling during long training sessions.

Sorry for missing this until now!

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This 2018 study suggests alginate doesn't help performance.

https://www.scienceinsport.com/...sted-sodium-alginate


Limitations on the study I can see (there will be others!):
* n=14
* Research at behest of one of the products, doesn't say it was double blind.
* Used products rather than studying alginate per se - there are differences in pH and carb composition as well as alginate.
* Not particularly high fuelling rates
* Much lower sodium compared to the Alacrity Endurance recommendations
* Only 2 hrs exercise

For sure. Sodium alginate is marketing, and is better replaced by sodium citrate.

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Dear Alex,

Can this sodium alginate be a cause of making my guts ‘work’ or is it more to find in the composition of Maurten.
I have had many full distance races go bas due to stomach problems.
In 2019 i did a ironman distance race on about 70 grams of plain dextrose powder, salt and a electrolyte tablet in a 750 ml bottle and drank 1 bottle an hour.
That worked although i came a bit short on fuel in the 2nd half of the marathon, but no stomach issues.
At some point i came to the conclusion fructose might be the cause.

Started with Maurten this year and can drink about 110-120 grams of Maurten in the bike but after a 5hr bike ride as soon as i get hime i have to take a stop ar the toilet for a code brown. Long runs, the same at about around 90-110 min in long runs when i use Maurten i have to get out of the pants.
No further stomach issues, so that’s good, but the shitty part is….wel pretty shitty. As so i had to get out of my run pants twice during my last ld race in september.

Any idea what could be the cause this gut ‘thing’? It just happens with Maurten, but most other sports drinks give my stomach issues.

Would it be an idea to get back to my dextrose mix and just try to add fructose by 10 grams portions and see at what level it might give me stomach problems?


Thanks

Jeroen

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Owner at TRIPRO, The Netherlands

The thing that makes maurten work: more fructose than most other beverages. It's 1:0.8 malto:fructose which is the same/better as 1:0.8 dextrose:fructose. Both achieve delivering 1:0.8 ratio (almost 1:1) of glucose:fructose. Maurten was the first product to do this. And it's why it works for so many people. The fact they use alginate might be slightly better than chloride, but the hydrogel thing is pure marketing. If alginate is better than chloride it's purely because you don't end up getting an overload of chloride in the gut. Sodium citrate manages this better, or can use a mix of mostly sodium citrate with a bit of table salt and achieve the same thing.

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Is that actually true?
Powerbar gels are also 2:1 glucose:fructose and there's other brands too.
Also, it's my understanding that a lot of the studies about mixing carbohydrates were made by Gatorade?

Yes. Maurten was first to do 1:0.8 ratio. This is not an endorsement of maurten.

I endorse sugar.

Yes, lots of the studies were done and influenced by Gatorade. They're a (the) primary reason you hear the numbers 30/60/90 & 2:1. Science isn't that pretty. Marketing is.

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so basically the "real" innovation of Maurten is simply increasing the proportion of fructose and going from 2:1 to 2:1.6.
I remember reading about the ration and not fully understanding why would Maurten decide to have a slightly different ratio.

If an athlete were to go over 90 g/h is there a benefit to hold that 1:0.8, assuming they can tolerate the high fructose or would it be better to have a different ratio?

Table sugar is supposedly 1:1. Is that an option for >120g of carbs per hour?

Yes.

&

Yes.

:)

Welcome to the dark side.

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But could the higher fructose rate could lead to the gut activity in your opinion or doesn't fructose have anything to do with it. I have read there are people with a fructose intolerance or havinf problems with fructose absorption.

regards,


Jeroen

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Owner at TRIPRO, The Netherlands