The Forum for Endurance Athletes


Postby JasLuc4 » Mon Jul 12, 2010 9:33 am

Just received this email from Dr. Mirkin....I haven't looked at the studies in detail so just presenting this as something new out there:

Sodas with HFCS and Caffeine May Be Best Drinks for Endurance

July 11, 2010

The limiting factor in endurance racing is the time that it takes to get enough oxygen into muscles to burn food for energy. Anything that reduces oxygen requirements allows you to race faster. Sugar stored in muscles, called glycogen, requires less oxygen than fat or protein. Anything that helps you keep sugar in muscles longer gives you greater endurance.

A study from Georgia State University shows that drinks that contain both glucose and fructose burn more carbohydrates than those containing only glucose, and allow cyclists to ride much faster over 60 miles (International Journal of Sport Nutrition and Exercise Metabolism, April 2010).

Most soft drinks are sweetened with high fructose corn syrup (HFCS). Both HFCS and conventional sugar (sucrose) contain a mixture of two sugars, glucose and fructose, in nearly the same concentrations: HFCS has 55 percent fructose/42 percent glucose, while sucrose is a 50/50 mixture. So the relative concentrations of glucose and fructose are not significant. However, the fructose in sucrose from cane or beet sugar is bound to glucose and must first be separated from it, so it is absorbed more slowly into the bloodstream. The manufacturing process for HFCS frees the fructose from glucose to makes it into a free, unbound form that is absorbed more rapidly into the bloodstream. This could cause a higher rise in blood sugar ((Pharmacology, Biochemistry and Behavior, March 18, 2010) and provide more sugar for muscles during exercise. We need to wait for more research to know if HFCS drinks improve endurance more those made with cane or beet sugar.

Caffeine increases endurance (Medicine & Science in Sports & Exercise, July 2010) by increasing absorption of sugar by muscles (Journal of Applied Physiology, June 2006). Those who took sugared drinks with caffeine were able to absorb and use 26 percent more of the ingested sugar than those who took the same drinks without caffeine.

On long rides, we drink colas for their sugar and caffeine. However, you should take sugared drinks only when you exercise and for up to an hour after you finish. Contracting muscles remove sugar from the bloodstream rapidly without needing much insulin. Taking sugared drinks when you are not exercising causes higher rises in blood sugar that increase risk for diabetes and cell damage.
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Postby PowerGoat » Mon Jul 12, 2010 8:44 pm


Yes, I read this also. That first sentence is very interesting, "The limiting factor in endurance racing is the time that it takes to get enough oxygen into muscles to burn food for energy." I would love someone with scientific understanding to explain it, agree or disagree with it, and then discuss the "time" issue. Endurance racing is slow-moving. Why is this oxygen race so important in endurance sports and not in fast-twitch events like 5k's, basketball, and etc.?

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Postby steve-born » Tue Jul 13, 2010 6:12 pm

Hi everyone -

I read this study with a significant amount of incredulity because of all we know of the health hazards associated with HFCS. There are numerous articles on our website that discuss this. Click on the KNOWLEDGE link and scroll down to the Endurance Library link. Click on that a you'll see a number of articles listed in the category of "Sugar and Sugar Substitutes." The primary ones I'd suggest are:

*** Dietary Fructose or Fructose Containing Sweeteners Negatively Impact Health
*** Fructose (Corn Syrup) is No Answer For a Sweetener
*** Fructose Increases the Rate of Aging
*** Fructose Sweeteners Negatively Impact Blood Sugar and Lipid Metabolism Inhibiting Energy Production

I read Mirkin's column and one of the sentences in it caught my attention:

"A study from Georgia State University shows that drinks that contain both glucose and fructose burn more carbohydrates than those containing only glucose, and allow cyclists to ride much faster over 60 miles (International Journal of Sport Nutrition and Exercise Metabolism, April 2010)."

What caught my attention was there was no mention of maltodextrin (complex carbohydrates) in the study; it was a glucose/fructose combination versus glucose. We know that maltodextrin is a superior carbohydrate source than any form of simple sugars (glucose, sucrose, fructose, etc), and we discuss this in detail in the article "Proper Caloric Intake During Endurance Exercise" at ... .1275.html and in the article "Simple Sugars and Complex Carbohydrates - An Incompatible Combination" at ... .2890.html

Anyway, I thought I'd pick Dr. Bill Misner's brain about this. As most of you know, Dr. Misner has long since retired from Hammer Nutrition. However, he and I correspond with some frequency so he is always very willing to discuss nutrition/supplementation/fueling topics with me.

Basically, I just wanted to get his opinion about this study. Here's what he wrote in his first reply to me:

There are a number of pathways that result in improved endurance performance, but unfortunately several of them also impose harmful side effects with use. The suggestion that HFCS enhances endurance performance demonstrates no concern for the harmful profound rise in blood sugar to insulin ratio. We know that insulin excess over time can contribute to numerous health issues such as Insulin resistance syndrome, obesity, and Diabetes II. This sort of nutritional heresy is based on an adage, "The ends justify the means." Following this sort of reasoning to improve performance, why not schedule a physician-administered injection of Anabolic Steroids, EPO, or Amphetamines prior to or during your next event?

Makes no sense whatsoever.

--- END ---

He then followed up with a short article he put together...

HFCS Now Equals Problems Later

High-fructose corn syrup's (HFCS) molecular structure is metabolized very different than common sucrose. Table sugar (sucrose) has a bound fructose molecule and a bound glucose molecule, once unbound in digestion, the fructose molecule heads off to the liver and the glucose molecule goes to the blood stream, HFCS contains unbound glucose and fructose molecules that enter the blood stream as reactive carbonyls. Reactive carbonyls are associated with weight gain, insulin resistance, leptin resistance, and diabetes II. Other problems with HFCS - according to Richard Bowen's teaching page at the University of Colorado - is flatulence, diarrhea, iron, magnesium, calcium, and zinc deficiencies, fructose malabsorption, cirrhosis, obesity, and cardiovascular pathology.

Elliot et al concluded that increased consumption of fructose (due to increase in dietary simple sugars or to the higher fructose content of HFCS) is obesity and insulin resistance. Stanhope et al show that HFCS is at least equivalent to the effects of sucrose. Bray concluded that HFCS is the cause of the current obesity epidemic. These structural properties of HFCS cause it to block insulin receptor sites. This makes more insulin available to throw into a tizzy metabolic cellular fats and sugars that could impose more harm than good.

My point is the immediate gains, if any, may mean harmful unwanted problems later.


Elliott, Sharon S; Nancy L Keim, Judith S Stern, Karen Teff and
Peter J Havel (April 2004). "Fructose, weight gain, and the insulin
resistance syndrome1". Am J Clin Nutr 79 (4): 537–43.

Stanhope KL, Griffen SC, Bair BR, Swarbrick MM, Keim NL, Havel PJ
(May 2008). "Twenty-four-hour endocrine and metabolic profiles
following consumption of high-fructose corn syrup-, sucrose-,
fructose-, and glucose-sweetened beverages with meals". The American
Journal of Clinical Nutrition 87 (5): 1194–203.

Bray, George A.; Samara Joy Nielsen and Barry M. Popkin (April 1,
2004). "Consumption of high-fructose corn syrup in beverages may
play a role in the epidemic of obesity". American Journal of
Clinical Nutrition 79 (4): 537–543.

By permission, courtesy of Professor R. A. Bowen
Department of Biomedical Sciences, Colorado State University, Fort
Collins, CO 80523
Pathophysiology of the Endocrine System @: ... .htmlbowen

--- END ---

I hope you will find this information useful and helpful. Personally, instead of putting my health at risk for a slight possible (key word "possible") enhancement to my athletic performance, I will avoid the known health consequences associated with HFCS consumption and stick with what has proven to work (complex carbohydrates), not only myself but for thousands and thousands of our athletes/clients.

Sincerely -

Steve Born
Fueling Expert
Event Sponsorship Coordinator
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