How are people getting 100g+ carbs in a bottle?

Is there science to show this?

Question isn’t a condemnation, I’m genuinely interested as I consume ‘sugar water’ on the bike.

Thanks!

Absolutely. Happy to clarify.

100g sucrose = 292 mOsmol/L

50g fructose = 277.5 mOsmol/L

50g maltodextrin with average strand length of 10 (1801g/mol) = 36mOsmol/L

36 (malto) + 277 (fruc) = 313.5 mOsmol/L

From the Gonzalez paper (GONZALEZ_2017_Glucose plus fructose ingestion for post-exercise recovery-Greater than the sum of its parts.pdf (1016.7 KB)
image

Also this paper shows super high exogenous oxidation rates using 1:1 ratio.
JENTJENS & JEUKENDRUP 2005 ‘1-1 ratio is good!’ high-rates-of-exogenous-carbohydrate-oxidation-from-a-mixture-of-glucose-and-fructose-ingested-during-prolonged-cycling-exercise.pdf (194.5 KB)

4 Likes

There is no need to keep concentration as low as the oft-cited 6-8%, or even 10-12%.

With some practice lots of folks tend to handle 12-18% just fine, especially in colder weather where hydration is less likely to become compromised.

120g/hr could be consumed with 750mL + 1000mg sodium via Sodium Citrate and you’re good to go.

FYI: Sodium Citrate has about 1000mg sodium per tsp. Table salt is about 2000mg sodium per tsp.

1 Like

Is citric acid the same thing as sodium citrate? I can buy citric acid at my local supermarket.

No, unfortunately. Sodium citrate replaces three hydrogens on the three hydroxyl groups of citric acid with sodium molecules. Once dissolved sodium citrate turns into 3 x Na+ and 1x citrate ion.

Once dissolved citric acid only has hydrogen ions to donate. Okay for sweetness-reduction. Useless for meeting sodium needs though!

Total FYI:
Using sodium citrate in place of table salt allows your gut to tolerate more sodium consumption during training. Sodium citrate has 3 sodium molecules for every 1 citrate molecule. Sodium chloride has 1 sodium molecule for every 1 chloride molecule. That means that for the same amount of sodium consumption, there will be a greater number of molecules ingested, if using table salt, rather than sodium citrate. Osmolarity is the number of molecules per unit volume of solution. Our gastrointestinal tracts are sensitive to very high osmolarity solutions. During normal daily living, consumption of very high osmolar solutions (lots of molecules per liter) causes a laxative effect 20-60 minutes after consumption. During exercise, it causes gut cramping, THEN a laxative effect. My personal experience with this can be described as “not fun!”

4 Likes

Bummer, thanks for the great response though.

I mix 1/2 cup maltodextrin, 60 grams of carbs, with 2 TBSPS of fructose, 33 grams of carbs, and a lemon lime flavor packet in 24 ounces of water. That’s around 375 calories. A gram of Maltodextrin or fructose yields about a gram of carbs. It would be easy to increase that to exceed 100 grams of carbs. I wouldn’t want to do a 1 to 1 ratio of glucose to fructose because it would be too sweet tasting.
I do several long slow rides/week, 3+ hours at around 75% of my FTP which burns around 1,300 or more calories. I drink a few swallows from the bottle every 30 minutes or so throughout the ride. At the ½ way point I stop at a c-store and have a Starbucks vanilla double shot, 210 calories, and a Natures Bakery fig bar, 200 calories. That comes to about 785 calories total for the ride. When I finish I have 16 ounces of chocolate milk for a recovery drink, about 360 calories. I typically have a serving of cereal with milk and blueberries and 3 eggs for breakfast before the ride.
If I’m going to ride longer and/or harder I’ll take two bottles. In the summer I fill a camelback with just water and add a little bit of sodium citrate to the bottle. I live in north central Texas and it gets very hot here in the summer. Lots of sweat!
I am taking in fewer carbs during the ride than I’m burning but not by much.
Describing this is making me hungry!

2 Likes

Is it energy density that matters or the ultimate number of particles that the carbohydrates are broken down before absorbed in the bloodstream? I guess it doesn’t matter if only adding carbohydrates to water. So how much water do we need then, it looks like 50g of fructose per liter gives about the right osmolarity, does that mean we should aim for 1L of water per 50g of carbs, regardless of where they came from?
Although I just did 1 bottle of 800ml with 120g sucrose and 60g of maltodextrin plus 1 bottle of only water, for a 2 hour workout. That felt quite good.
Will try a higher concentration of fructose next.

Thanks for the resources.

Now wondering if/how a GLU+FRUC mixture differs from a straight SUC solution?

There is no need to break the G-F mixture (as there is with SUC) for absorption, so what effect does this have on the body (e.g. hormone release, etc.)?

Sucrose works virtually identically to glucose plus fructose.

1 Like

100-150g/L usually works out well.

Energy density matters more than osmolarity (molecule number) by a wide margin. So much so that some of my peers pay absolutely no attention to osmolarity anymore.

Alex,
what are your thoughts/tips on using a concentrated bottle for nutrition?

For the bike leg of my last IM I mixed 280g of maltodextrin in an 800mL bottle, which would last for 4h (so 70g of carbs per hour). After every sip of the concentrate, I would take an equal sip of water in order to avoid any stomach issues. While it did seem to work, I am interested in improving the mix by adding fructose.

Thanks for your contributions, it has been interesting reading.

1 Like

That’s precisely what my wife and I do. Usually 250-500g carbs in a 1 L bottle. Swig the carbs, then chase with water.

Read more throughout this thread here Help me calculate an at home "maurten" drink (im bad at math) (Page 2): Triathlon Forum: Slowtwitch Forums

Look for the pics of my wife’s bottle prep for her single-day Festive500.

2 Likes

I am getting so confused between the types of sugar.

So feasibly you could just mix 100g table sugar (sucrose?) with water and you’d have a even split (50-50) between glucose and fructose?

But in your slowtwitch posts, you suggest mixing Gatorade with table sugar, is that to make it more palatable as 100g of table sugar would be too sweet? What type of sugar is in Gatorade? Isn’t it a mix of glucose and fructose already? :exploding_head:

Thanks for posting btw, it’s useful to be able to clarify.

2 Likes

This bit still hurts my head a little. I always wondered how fuelling anything under an hour could help as I always hear people saying you need to fuel 3 or so hours before a ride. So how does fuelling while on a 60 minute trainer session help? :flushed:

The 3 hours in advance thing is when you have a complete meal as part of normal nutrition. You might eat more carbs than normal in preparation of an intense workout and what this does is fill up your glycogen storage, I believe this is in the liver and in the muscles.

During the workout it only makes sense to ingest quick carbs that are much faster absorbed. So sugar in water just takes minutes. For workouts shorter than 1 hour it is not an absolute necessity to eat, because you should have enough energy stored.

But, ingesting quick carbs during the workout, also shorter ones, for me makes the workout easier and that is also what others have experienced. I can imagine a few reasons why:

Our bodies are not digital on/off machines and there are mechanisms in place to protect you from dying if you forget to eat. So your glycogen storage is not like a fuel tank that can be used at full speed until empty, rather your body starts to slow down fuel consumption before it runs out. So by ingesting glucose, you will stay longer out of the almost empty zone where less glycogen is delivered to the muscles.

For fructose I can also imagine that although it takes a long time before it is actually used as glycogen, just absorbing it might already tell your body that glycogen is on the way and it could already release more of the stored glycogen. I know it works like that if you just rinse your mouth with something sweet.

3 Likes

Nice reply, many thanks!

Maybe it is a coincidence, but if you dissolve carbs in water, then having the same energy density also means roughly the same osmolarity once all the molecules are split into glucose and fructose.

Yup! Correct.

I like the taste. :wink: It’s still similarly sweet, but with a lower flavor intensity than if you were to do 100% Gatorade powder to get to the 100g, and with more optimal sugar ratios and cheaper cost.

Gatorade is sugar, then dextrose, per their ingredients list. Companies won’t give away their industry secrets like sugar ratios. I’ve asked! If they’re smart, it’s almost entirely sugar. If not, it’s probably close to 1:1 sucrose to dextrose, which yields 2:1 gluc:fruc ratio. I’m guessing it’s that, because Gatorade is a huge 2:1 proponent.

FYI: dextrose = glucose. Dextrose = outside the body. Glucose = inside the body. Silly nomenclature, alas.

@mrpedro nailed it. Intra-workout carbs increase cognitive drive and keep blood sugar elevated (ideal!) during training. Pre-training meals 2-3 hrs before, stock a bit of glycogen and pre-boost blood sugar for training start.

Osmolarity of glucose + fructose is almost double the osmolarity of sucrose for an isoenergetic solution, I believe, but have not checked the math. Maltodextrin + fructose almost matches sucrose for osmolarity of an isoenergetic solution.

I don’t believe that sucrose is hydrolyzed (split) into gluc + fruc when dissolved in water. Only once an enzymatic breakdown occurs would osmolarity increase, and I need to brush up on precisely where and in what parts of the GI tract that occurs, and at what rates, and by what mechanisms :wink:

I tend to stay quite “applied” in my research and once I find the answer like “sucrose works as well as malto+fruc” I tend not to dive too deep mechanistically. Too many rabbit holes and too great of time-cost. And many of the greatest misconceptions in sport science have come from mechanistic understandings without actual testing in vivo! (see 30/60/90g/hr fruc/gluc/sugar dogma! lol)

3 Likes

Yea, in water it doesn’t split. But it looks like all the sugars are split into glucose and fructose before it goes through the intestinal lining. See for example: What Is the Difference Between Sucrose, Glucose & Fructose? | Healthy Eating | SF Gate

I can see the bit where you just want to focus on results. There are too many correlation-not-causation things going on, where we don’t fully understand the underlying mechanisms and are too quick coming to conclusions.

For me, I must say that the 2 times I did use sugar during a workout it really made the long intervals around threshold much easier.

1 Like