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Old 06-13-2004, 06:41 AM   #1
Paul Kayley
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Big race coming soon... need information regarding the effects of fat intake upon rate of rehydration. I want to eat fats during my 10 hour race but dont want to compromise race-hydration... has anyone encountered research which might indicate impaired gatric emptying/intestinal water absorption due to fat ingestion??? Either that or your thoughts?
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Old 06-13-2004, 07:57 AM   #2
Ross Hunt
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Paul,

Are you planning on eating just fats?
I'm no nutritional expert, but it seems like doing a 10-hour fat fast in conjunction with a race is a recipe for ketosis, so wouldn't eating only fats for the race cause massive dehydration?

Just a shot in the dark,

Ross
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Old 06-13-2004, 09:28 AM   #3
Paul Kayley
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Sorry Ross, I didnt make myself very clear... in a rush as usual! I want to eat MCTs in form of coconut oil combined with chocolate, AS WELL AS my carbohydrate/electrolyte drink. Intend to try in training first but reading existing research would be nice.

PS that was meant to be 'gastric'!
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Old 06-13-2004, 09:38 AM   #4
Paul Kayley
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I think what I'm asking is...
"Does eating fats during exercise, slow down the absorption of water from the intestines?"

I know that reseach has found that drinking a fluid too rich in carbs/electrolytes can slow gastric emptying and therefore rehydration potential.
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Old 06-13-2004, 05:50 PM   #5
Jay Edvardz
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Possibly a bit off topic; when I eat a good deal of fat and drink a good deal of water, I tend to feel extremely nauseous.

-Jay
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Old 06-14-2004, 09:49 AM   #6
Neill S. Occhiogrosso
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Paul:

How do you intend to use the coconut oil? I bought some too, for MCT purposes, without realizing that it was solid. I have no idea what do to with this stuff now.
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Old 06-14-2004, 11:07 AM   #7
Brian Hand
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Neill, the coconut oil is solid at room temperature, but just barely, at least that's what I've found. If you leave it in a warm spot, I'd guess 80 deg F, it turns liquid. The kitchen cabinet over my refrigerator is warm enough to keep it liquid in the summer. I'm not sure if it will be the same for all brands.

It works okay solid for frying and in the blender in a protein shake.
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Old 06-14-2004, 02:28 PM   #8
Paul Kayley
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Neill, I use it in making curries generally, but I want to try mixing it with cocoa and sugar as a chocolate race bar.
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Old 06-14-2004, 10:33 PM   #9
mark twight
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Paul,

During your next long training efforts (i.e. before the race) try eating according to your heart rate.

The issue you asked about is gastric emptying, which can be compromised by food intake at high heart rates. Carbohydrate gels are the obvious solution because they are in and out of your stomach before much blood is robbed from circulatory system where it is needed to transport O2 and dispose of the byproducts of muscular contraction. Steal too much and performance declines. In relation to hydration: if water is in short supply stick with carbohydrate gels as the primary energy source because these require less water to digest and absorb than other sources that include fat and/or protein.

During long effort (these days) I eat only carb gels if my HR is above 150 BPM. When it's 130-135 or lower I eat anything because even if blood is robbed to prepare the food for digestion I am so far below my threshold that I have it to spare. Between 135 and 150 I am careful to limit intake to small volume, low calories but I still eat more or less anything.

Prophylactic protein intake reduces muscle catabolism and speeds recovery. So you should eat some during the race, in low-calorie (under 100) doses.

A 4-hour effort (which implies a low level of work intensity) is fueled predominantly by fat:
4:00+ hours = 62% energy from fat, 30% from blood glucose, 8% from muscle glycogen.
As duration exceeds four hours the percentage of energy derived from fat metabolism during sub-maximal exercise may be as much as 70-80%.

You probably have plenty of fat "on board" to fuel the whole race. That said, fat intake is likely helpful during long effort. I don't necessarily believe you will be taking advantage of the calories you eat -- if memory serves it is easier (or faster) for the body to metabolize stored fat than to metabolize recently eaten fat. I think fat intake during effort lets your body know more fat is available and that it is OK to release stored fat for energy production. A "mystic" connection to be sure but one experienced by many endurance athletes. Another advantage is that acidity levels may be controlled though fat intake; by eating fats that have an acid buffering effect like sesame seeds and sunflower seeds (go for the unsalted if you can get them down as this will further reduce acid burden). I have had good success lately with fat intake during effort as long as I am disciplined enough to ingest small doses and maintain carb intake as well.

It is important to maintain blood glucose levels in order to metabolize fat. This is the basic process (too simple for the academics but as understandable as I can make it): Fatty acid breakdown requires plenty of oxygen and the continual background support of carbohydrate catabolism, meaning the body stokes the fire that burns fat by oxidizing carbs. These carbs come from stored (muscle) glycogen and, as that declines, blood glucose. When stored glycogen is used up, and blood glucose levels dip, fat metabolism slows. To combat this the liver donates liver glycogen to maintain blood glucose levels in order to burn fat. Once liver glycogen is near depletion the body has burned through all easily accessible forms of stored glycogen and the liver must convert lactate, pyruvate, free fatty acids and amino acids, into blood glucose (through a process called Glyconeogenesis). The initial source of these amino acids (that are being converted to glucose) is the blood where the Branched Chain Amino Acids Leucine, Isoleucine and Valine are found. These amino acids are essential to both aerobic and anaerobic exercise. After roughly an hour of conversion all these BCAAs have been extracted from the blood so the body cannibalizes muscle to access them. This process may account for 5-12% of energy during long term effort but the downside is diminishing muscle volume and ammonia, which is a byproduct of breaking down protein (muscle) to access amino acids. Ammonia is a very powerful catabolic and highly toxic to the cells. Excess ammonia in your body compromises physical performance and causes a decline in cognitive function.

Maintaining a supply of BCAAs in the blood (through consistent supplementation during effort) helps prevent muscle catabolism. Supplementing BCAAs during effort can also forestall increasing levels of free Tryptophan in the blood that occurs as other BCAAs decline. Tryptophan competes for entry into the brain via the same amino-acid carrier as Leucine, Isoleucine and Valine and as they decline the Tryptophan crosses more easily. Higher levels of Tryptophan in the brain promote the formation of the neurotransmitter 5-hydroxytryptamine (5-HT) which induces sleep, depresses motor neuron excitability, influences autonomic and endocrine function, and suppresses the appetite. This has a negative effect on decision-making capacity so if the race is anything but mindless, consequnce-free effort pay attention to the Leucine and Valine supplementation.

I just previewed the post and it's way longer than I thought. If it sparks more questions I'll try to answer -- if I don't it's a time management issue. And if it helps your race nutrition I want to read about it.


Mark T.


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Old 06-15-2004, 05:06 AM   #10
Larry Lindenman
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Mark, wow. In light of your excellent answer this sounds like a stupid question but. . .what do you eat prior to a CF like workout? ie. short duration high intensity. By the way, I have a masters degree in exercise physiology (1986) and this has to be one of the top three posts I've ever read!
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