Comments On Long Chain or "Slow Burn" Carb Fueling

Presenting long chain or "slow burn" carbohydrates for athletic fueling has been a great marketing story, but is of no value to the exercising athlete who is ingesting carbs and other foods during an event. In fact, in a prolonged event, such advice will lead you to one place – bonking! “Fast burn” carbs, also called high glycemic index carbs, include dextrose, the principal carb found in Eload(TM). “Slow burn” carbs, also called low glycemic index carbs, include fructose. Interestingly, many companies advocating use of “slow burn carbs” are referring to maltodextrin, amylopectin starches and glucose polymers, which are all fast burn or high glycemic carbs! The question is: When do you need your carbohydrate, now, or later? If you are working even moderately hard for prolonged periods, you better believe it, you need it now! If you are out for a family stroll in the park, then eat all the slow burning carbs that you want – you won’t need them anyway at such a low level of activity!

Lets look at it another way. If you are burning carbs at a rate of 60 grams/hour, then you need to be absorbing these at the same rate, otherwise you are headed for eventual bonking. What good is a bunch of carbohydrate sitting in your gut for long periods of time, as all slow burn carbs do, when your muscles, heart, brain, liver and kidneys are all crying for carb now, this second! The truth of the matter is that the more rapid the carbohydrate release during exercise, the more your body is readily supplied with glucose – NOW, WHICH MEANS NO BONKING!

Carbohydrate Comparisons

There are several commonly used carbohydrates in sports drinks. These should be compared based on their effects on the following:
1. Gastric Emptying
2. Gastrointestinal Irritation
3. Digestion
4. Absorption
5. Exercise Fueling
6. Post Exercise Glycogen Recovery
7. Effect on Fluid/Sodium Absorption
8. Glycemic Index

Go to this link to see our carbohydrate comparison chart.

Sports Drink Sweeteners

Sports drinks must be sweetened to enhance their taste, there's no doubt about that. Studies have also shown that flavor drives your thirst mechanism, while water, without flavor actually shuts off your thirst mechanism. Again this shows why water is not a very good choice for hydration. Currently, there are several ways to sweeten a drink:

1. Artificial Sweeteners:
These include Nutrasweet(TM) (Aspartame), Splenda(TM) (Sucralose) and Sweet One(TM)/Sunette(TM) (Acesulfame K). At e load(TM), we don’t like artificial sweeteners, for several reasons:

i. They do not supply carbohydrate energy because they are not carbohydrates.

ii. Sucralose is not even absorbed into the body, and its presence in the gut in high concentrations may contribute to bloating, gas and diarrhea.

iii. The safety of both all of these products is still a concern in some circles.

2. Natural Sweeteners:
While there are many natural sweeteners, most commonly used in sports drinks are fructose (fruit sugar) and sucrose (cane/table sugar). Fructose has been mentioned several times, and its low glycemic index, along with its known potential to irritate the gastrointestinal tract, makes it a bad choice for a product designed to help athletes in the heat. These negative effects increase in direct proportion to the fructose concentration in the product.

Sucrose is the logical choice for e load(TM). It is natural, provides a good source of carbohydrate energy (sucrose has a GI of 64), and does not produce gut irritation. It is easily absorbed and pleasantly sweet, improving palatability. Some people are concerned about sucrose, and some companies take advantage of this concern by continuing to perpetuate the myth that a little table sugar is somehow going to lead us to our destruction! In truth, no one single carbohydrate should be the principle carbohydrate in our diets, and for some people, sucrose is the principal carbohydrate ingested on a daily basis. The medical staff at e load(TM) agree that this is not ideal for optimum health. However, some sucrose in our diets is perfectly fine, and as a palatable, non-nauseating sugar that offers rapid absorption and fueling, sucrose works very well, especially in the heat.

A final note is the stevia plant, which produces a natural, no calorie sweetener that is being used more and more in various foods/products on the market. Our problem is this: if it doesn’t have any calories, it is of no use during exercise i.e. it is analogous to any of the other non-caloric sweeteners like aspartame, sucralose or acesulfame K in this regard.

Insulin and Glycemic Index

As mentioned, the Glycemic Index (GI) is a scale that has been developed to measure the ability of foods to elevate blood glucose levels. Since insulin is elevated in response to rising blood glucose levels, the glycemic index can also be an indicator of how much insulin will be released from the pancreas in response to meal ingestion. The higher the number on the index, the more rapid the food can elevate glucose in the bloodstream, and the more potent the potential stimulus to the pancreas to secrete insulin. Carbohydrates like dextrose, amylopectin and maltodextrin, are very high on the GI (about 100), and therefore can be a strong stimulant to the pancreas to release insulin. Sucrose has a more moderate GI of 64, with a more moderate release of insulin. Fructose has a GI of 24, galactose 22, and fats and proteins are also low on the glycemic index. Therefore, in order to keep insulin levels balanced, choosing foods lower on the glycemic index is advocated as a way of controlling the secretion of insulin. However, these principles are only relevant during non-exercising times.

What Happens During Exercise?

It is well established that different sets of rules operate during exercise, where secretion of catabolic/counter regulatory hormones is high, and secretion of insulin is low. In fact, the more strenuous the exercise, the lower the levels of insulin, regardless of the types of food and drink you may be ingesting. This balance of hormones helps ensure that a steady supply of glucose and free fatty acids are available to provide energy to muscle cells, and helps explain why hypoglycemia secondary to insulin release is not observed during exercise.

Insulin - Your Friend and Enemy

Insulin, made in the pancreas, was first discovered in 1921, and has many different bodily functions, all of which are directly related to cellular metabolism. Its major function is to regulate total body glucose in all body tissues except the brain, and it achieves this effect by stimulating glucose uptake primarily in muscle and fat cells. It is secreted by the pancreas into the bloodstream in response to rising blood glucose levels after a meal. Rising amino acid levels (found in proteins) also stimulate insulin release, though to a lesser extent. Insulin is an anabolic hormone, which means that it is responsible for building and storing various substances within. An example is glycogen, which is the animal storage form of glucose, primarily found in liver and muscle cells. Without insulin, the cells in our muscles and liver could not absorb glucose and therefore could not make glycogen. This is contrasted to catabolic hormones, such as adrenalin, glucagon and cortisol (also known as counter regulatory hormones), which are responsible for helping our bodies break down and utilize various substances, including glycogen and fats. Under the influence of these catabolic hormones, glycogen is broken down to glucose, and fats are broken down to free fatty acids. Both glucose and free fatty acids are important for sustaining exercise.

Some people cannot make insulin, or their bodies’ cells have reduced sensitivity to insulin. Both of these problems are features of diabetes. We also now realize that too much insulin, known as hyperinsulinemia, can also be a problem, and can be associated with many illnesses including high blood pressure, high cholesterol and heart attacks, to name but a few. Normal insulin levels are therefore important for healthy living.