Sugar Absorption, Hot Supermodels, and Half Iron Nutrition

Triathlon Forum
1

OK. So my post has nothing to do with supermodels, but since you are here… :slight_smile:

In this months (Sept 2006) Bicycling magazine, there is a good article about Sugars. It talks all about how different sugars are processed by the body, and how to best use them in training. Among the statistics, it says that traditional scientists (used to?) think that the max rate the body could absorb glucose, was about 1.1 grams per minute. Then they go on to say that Asker Jeukendrup of the Univ of Birmingham uses a sugar blend (2:1 mix of maltodextrin to fructose) to oxidize at 1.5 grams per minute. Another unnamed study showed that fructose and sucrose could bump the levels to 1.7 g/min.

The articles then goes on to say that if an athlete is trying to intake 300 or so calories an hour, then the appropriate amount of sugars required to yield those calories would be “more than most can tolerate.” He then touches briefly on bars but only consludes that eating them “all at once can also be hard to stomach”, but doesn’t speficy any amounts, or shed any light on whether or not bars (containing some protein and or fat) can yield more digestible calories than sugar, per gram per hour.

My conundrum, is that I’ve assumed (with my utter lack of scientific equipment) that if I can indeed start to consume gel and/or gatorade during a race, a half ironman for example, and I keep the gels or gatorade flowing, my body should be able to absorb a conservative 1.25 grams per minute. That means that I’m oxidizing 75 grams over an hour. That’s right around the 300 calories per hour that some would heartily recommend for a race of HIM intensity. (maybe a 5-5:15 hilly pace; I’m doing Grand Columbian Half in Grand Coulee, WA in Sept. Avg temp 90, low humidity, etc.) Is this really to much to stomach?

More specifically 24 oz of gatorade (with 45g of carbs, and 174 Cal) and 1 Gu (with 24g carbs and 100 Cal), puts me right about where I think I need to be in terms of what my stomach can absorb, per hour, with enough calories to keep me going for 5-6 hours.

So…what’s the question?

  1. In order to maintain the most optimal osmality (sugar to water ratio for best absorbtion), I’m looking at my 24 oz of gatorade, my theoretical 1 gu, and another 16 oz. of water to balance out the Gu, per hour. In training, even at high intensities, that’s way more than I’m used to drinking (like, double). Not to mention that putting on 24 oz of liquid an hour makes me have to pee a ton, at least once an hour. And peeing three times on the bike just seems excessive. Double the liquid, and I’m peeing all day long. Is this normal? Do I cut back on my liquid intake, and just try to survive with less calories? Do I just pee lots and accept that good nutrition for this kind of race is going to keep me flowing?

  2. Since I’m drinking extra water to offset the Gu, should I just stick to pure Gatorade, or is there some beneift to mixing the sources of energy. Or do I look at some other type of gel, bar, or energy drink to combine or replace the Gatorade? (I’m leaning away from drinks that aren’t available on course, but welcome suggestions)

  3. I’ve heard all kinds of stuff about salt this and salt that. But I’ve never really seen any quantifiable starting point for hourly salt tab intake for a higer-intensity HIM performance. So Since I have six weeks to practice my nutritional regimen before race day, can anyone give me a jumping off point for salt tab intake with the above theoretical situation? Or will Gatorade Endurance do the trick, and eliminate or minimize salt tab needs?

  4. Do I need more calories than 275 an hour? And if I do, how do I get it if my stomach, according to these scientists, can’t absorb more carbs than it already is in my theoretical scenario???

As always, I thank you in advance for your comments, insight, or totally off-base anecdotal and non-relevant comments.

2

I would consider more gel, no Gatorade, whatever water it takes to get the job done. Use eGel/Crank and get as much or more sodium than that awful sugary Gatorade.

3

Go to infinitnutrition.com and look around. Read up on their take on multiple types of carbohydrates and calorie uptake, and on osmolality.

I took in nearly 40oz/hour (using infinIT with ~550mg sodium per 20oz) during the bike at Eagleman without any GI issues. Peed once on the bike and once on the run.

Rough estimate: 300 cal swim, 2100 cal bike, 1600 cal run, total 4000 calories. Figure 75% from carbs (if you are working reasonably hard) for 3000 carb calories. You have ~2000 carb calories stored, say you use 80% of them, or 1600, net deficit now 1400 calories. Figure you have 700 calories in your digestive system from a hearty pre-race breakfast, net deficit now 700 calories. Take in 275 calories per hour on the bike, total ~700: net deficit zero.

As always, YMMV.

4

Is it really average temperatures of 90 degrees in mid-September at Grand Coulee? Hm. Oh well-- I’m getting my heat training in.

I don’t know how to answer your actual question although I wonder if you have to pee every 15+ miles on training rides too. If so, seems like you could try some things out in training to see if other approaches yield better results. The thing about published (or unpublished) studies are they are generalizations about a population and don’t necessarily tell you what YOU need to do to optimize your experience. If you’re peeing too much, experiment with less fluids or stronger concentrations, whatever. Find out what works for you and what doesn’t.

I’ve never had to pee in a half ironman, although I come in fairly well hydrated off the bike but am not able to take in lots of fluids while running, usually water supplemented by a little goo and lots of salt tablets. But then I sweat lots.

Why don’t you do the ITU Long course distance? More people should sign up for that.

aliciap

5

Go to www.infinitnutrition.com and all your problems will be solved.

You don’t hafta worry about the osmolality, they do that for you. You can mix and match carbs, protein, amino acids, electolytes, even antioxidants and caffeine if ya want 'em (I didn’t).

I was able to very comfortably get down close to 500 cals / hr at IMLP on the bike using my custom InfinIT blend. Zero digestive issues. No cramping.

For a half I usually only need about 300-350 cals / hr. Since I’m going harder, it’s harder to take in and digest more cals; and since the race is shorter, I last longer on my pre-race cals before my during-race nutrition needs to kick in.

6

I agree to ditch the Gatorade and go with more Gu or gels and drink water. The simple sugar in Gatorade has a limited absorption rate, but the maltodextran and other complex sugars can be absorbed at a higher concentration - up to 2-3x and mixing them compromises this. There are articles along these lines provided by Hammer Nutrition, that of course push their own products, but from my experience work better than Gatorade.

7

My bad.

The average temp in Grand Coulee in September is 75. I guess I’m assuming the worst due to rampant global warming! :slight_smile:

And I didn’t want to the the ITU long, since I like the challenging bike for the half better. And I have some bets with friends that are doing the Half.

In regards to peeing. I usually pee every 45 min to an hour during training rides, and just kind of assumed that was the way it was. Even in most Oly races I’ve done, I’ve had to pee twice on the bike, and get pretty full during the run. Maybe I’m just overhydrating, but based on weight lost during excercize, I don’t think I am.

Thanks for the tip on infinit. I’ll have to check them out and give it a try.

8

You should try and find information about how much water the body can absorb as well. I’ve heard anywhere from 4-5 oz. per 15 mins btu I could be wrong. But there could be a study on it out there like the one you found on sugar absorption. 40 oz seems like too much.

9

So my post has nothing to do with supermodels, but since you are here… :slight_smile:

Damn! I’ve been duped!

10

<< Even in most Oly races I’ve done, I’ve had to pee twice on the bike, and get pretty full during the run. Maybe I’m just overhydrating >>

Maybe?? Not maybe, definitely. “Put down the water bottle, step away from the aerobottle, and come out w/ your fuelbelt unfastened and hands up!” :wink:

I’ve never peed during an Oly (well, not counting the nervous standing around and peeing in my wetsuit beforehand :wink: Out of 3 HIM’s I had to pee once. On a 5-6hr training ride I might hafta pee 2 or 3 times.

I’ll go out on a short limb and say that, if you hafta pee during an Oly at ALL, you are overhydrating. You (generic you) could probably finish an Oly w/ zero fluids or calories consumed. Yer not gonna die from malnourishment or dehydration during a 2-3hr event.

The fine folks at Hammer nutrition have some great info about hydration on their website (and also in a handy little booklet). Bottom line is, you probably only actually need 16-24 oz of fluids / hr. Maybe if it is insanely hot and humid you might need as much as 32oz / hr.

11

You should try and find information about how much water the body can absorb as well. I’ve heard anywhere from 4-5 oz. per 15 mins btu I could be wrong. But there could be a study on it out there like the one you found on sugar absorption. 40 oz seems like too much.
Gordo stated on his forum that he once drank 13 liters of fluid during a 6 or 7 hour bike ride.

12

I am also a fan of Infinit nutrition cuz of the osmolality. I can tolorate 300 cals per hour easily with it in 20 oz of liquid. I have been sucessful in combining it with GU also.

I have also done 3 gels (GU) per hour with water but I lack the electrolytes with that formula.

The best info I have read about this subject is in the book the “Lore of Running” by Tim Noakes. He presents several different energy models and their pros and cons.

jaretj

13

I agree to ditch the Gatorade and go with more Gu or gels and drink water. The simple sugar in Gatorade has a limited absorption rate, but the maltodextran and other complex sugars can be absorbed at a higher concentration - up to 2-3x and mixing them compromises this. There are articles along these lines provided by Hammer Nutrition, that of course push their own products, but from my experience work better than Gatorade.

Great thread. It is good to see that we are now starting to be aware of these issues. This stuff is being talked about more and more at the coach and nutritionist levels.

As far as simple sugars and limited absorbtion, that is not really what the science says. Actually if you mix maltose with a glucose and a sucrose or even fructose (not my fav carb in the world because it can cause some GI issues) you can increase your ability to oxidize carbs by up to 40%. That is a huge number. I am a huge believer of as many carb sources as you can get. Even if you are a carbo-pro user, throw some gatorade powder in there and it will be FAR more efficient.

There is some interesting SOLID reasearch being done about protein right now that looks very promising. I will post when it is final.

my 2c

14

<< Even in most Oly races I’ve done, I’ve had to pee twice on the bike, and get pretty full during the run. Maybe I’m just overhydrating >>

I’ll go out on a short limb and say that, if you hafta pee during an Oly at ALL, you are overhydrating. You (generic you) could probably finish an Oly w/ zero fluids or calories consumed. Yer not gonna die from malnourishment or dehydration during a 2-3hr event.

The fine folks at Hammer nutrition have some great info about hydration on their website (and also in a handy little booklet). Bottom line is, you probably only actually need 16-24 oz of fluids / hr. Maybe if it is insanely hot and humid you might need as much as 32oz / hr.

I’ll call your " limb " Murphy’s Law.

In general , I would pretty much agree entirely with everything you are saying.

Although I do disagree with " You could probably finish…during a 2-3 hour event ".

If you are in most climates, with average ,to low humidity and temperatures below 25c ( I would suggest) ,I would agree with you , provided the individual was properly hydrated and glycogen levels full.

IN HOT (25C and higher ) HUMID ENVIRONEMENTS:

When humidity increases , the body’s ability to cool itself is further impaired / slowed , which substantially alters the necessity for sodium supplementation.

I presume ,it would be possible to “complete” as per se , but I would put money on medical attention being required.

I live and train in 30c plus , daily , with high humidity. On the rare ( unfortunate ) occasions where incorrect planning / strategy ,regarding nutrition , has forced me to not have correct supplementation… the preliminary signs of heat exhaustion are obvious.

I could quote numerous factual examples supporting my argument , but think you are probably on the same page as I am.

Great weekend ahead !

15

Not to mention that putting on 24 oz of liquid an hour makes me have to pee a ton, at least once an hour. And peeing three times on the bike just seems excessive. Double the liquid, and I’m peeing all day long. Is this normal?

One thing that I would offer up to you is that while exercising, you may find that you won’t have to pee as often. The reason for this is your increased amount of sweating. Sweat is water exiting your body so it is used and excreted before becoming waste.

17

I also use Infinit and have had good luck. Adjusting the formula is great. One thing to look out for. If you push the osmolality on your infinit to the top of the range, then add additional sodium from another source, then you’ll be way over and risking problems.