The Science of e load ™
In the heat, especially when exercising, taste perception changes, when things that taste normal at rest suddenly seem overpowering, even nauseating (11,12). e load™ is formulated to reflect this fact. When mixed according to the instructions, e load™ actually tastes a little "dilute" from a flavor perspective than when sampled at rest, but has a full, refreshing flavor during exercise.
Additionally, with our "natural only" policy, e load™ contains only natural flavors, and nothing artificial.
Finally, e load™ has no syrupy, sticky taste, purposely being formulated with a 5.4% (54 grams per litre) carbohydrate concentration compared to a range of 6-8% (60-80 grams per litre) in most of our competitors. Again, in the heat, this is an important consideration in preventing nausea.
Marginally dilute taste at rest; full taste during exercise
Not too syrupy during exercise; no "pasty" mouth feel
Absolutely nothing artificial!
•The most important sweat electrolyte is sodium, with an average concentration of 800 mg/litre (39), and with an average as high as 1000-1100 mg/litre, especially in hotter, more humid environments (14, 40). Under-replacing sodium can lead to heat illnesses including dehydration, muscular cramping, headaches, gastrointestinal upset, nausea, fluid retention and hyponatremia.
•Potassium is the second most important electrolyte in sweat. Under-replacing potassium can substantially affect sodium balance, contributing to heat illnesses.
•Calcium, magnesium, zinc and choride are also important electrolytes found in sweat. Calcium and magnesium deficienies may contribute to muscular cramping.
•The sodium:potassium ratio in sweat is about 3-5:1 - your drink should reflect this.
•The calcium:magnesium ratio in sweat is about 2:1 - your drink should reflect this.
Electrolytes (sodium, potassium, calcium, magnesium, zinc and chloride) are an incredibly important part of a sports drink for performance in the heat, and all are lost through sweating. Electrolytes are responsible for maintaining many functions in the human body, including normal muscle contraction, blood pressure, nerve conduction, heart rate and gastrointestinal motility, to name a few. They also play an important role in energy metabolism. Allowing electrolyte concentrations to fall below normal through the process of sweating can contribute to the many problems discussed in the "Heat Stress and Heat Illness" section, including muscular cramping (13). This is a crucial issue in managing heat stress; however, most sports drinks have minimal and/or incomplete concentrations of electrolytes, and do very little to counter the electrolyte depleting effects of sweating.
Average Amounts in Sweat
The sodium concentration in sweat averages 800 mg/litre (39), and may average as high as 1000-1100 mg/litre, especially in hotter, more humid environments (14, 40), and varies by diet, sweating rate, hydration, and degree of heat acclimation (39). Sweat glands reabsorb sodium, but the ability to reabsorb sweat sodium does not increase with the sweating rate; thus, at high sweating rates the concentration of sodium in sweat increases (17). The potassium concentration in sweat averages 195 mg/litre; that of calcium, 50 mg/litre; that of magnesium, 25 mg/litre, and that of zinc, a trace mineral, less than 1 mg/litre (45). Gender, maturation, and aging do not appear to affect sweat electrolyte concentrations markedly (39).
Compare this with most sports drinks, which typically have between 120-430 milligrams of sodium per liter, falling far short of the ideal. A higher sodium drink helps prevent heat cramps and other manifestations of heat illness, stimulates thirst, reduces urination, and enhances dextrose (glucose) absorption from the small intestine (4, 13).
Also, compare most sports drinks, which typically have between 80-115 milligrams of potassium per litre. Falling potassium levels can contribute to all of the heat illnesses, including cramping and hyponatremia (15, 16). Deficiencies in one or both of these important electrolytes can have detrimental effects on exercise performance, especially in the heat. In addition, the sweat sodium : potassium ratio in humans is between 3:1 and 5:1. We are amazed at how many formulas out there ignore this important physiological truth. Some drinks even have more potassium than sodium in them. This would be great if your sweat had more potassium than sodium in it, but this isn't the case.
Also, the calcium : magnesium ratio in sweat is about 2:1, and your drink should reflect this. Replacing these important electrolytes in these ratios is important in order to optimize your function and performance, especially in the heat. Calcium is important for normal muscle contraction and nerve conduction (hence, it probably has a role in preventing muscle cramps), and replacing calcium may have role in protecting bones from reduced bone mass secondary to inadequate replacement of sweat calcium losses (38). Magnesium may also have a preventative effect on muscle cramping (13). Most sports drinks offer no calcium or magnesium. Finally, e load™ also contains zinc, another important electrolyte lost in sweat that is associated with optimal energy metabolism, endurance and tissue regeneration. Athletes may have a zinc deficiency induced by poor diet and loss of zinc in sweat and urine (41).
Being specifically formulated for the heat, e load™ has 1.095 grams of sodium citrate per litre, and 186 milligrams of potassium chloride per litre. Calcium carbonate is present at 72 milligrams per litre, and magnesium citrate at 78 milligrams per litre. Finally, zinc citrate is present at 6 milligram per litre. All numbers reflect average sweat composition, and important ratios, of the key electrolytes found in sweat. These electrolyte levels can be topped up to higher levels with the use of ZONE CAPS™, our electrolyte containing capsules, which can be used with e load™ (See Customizing Your e load™). Sweat electrolyte concentration increases proportionate to sweat rate, and the e load™ customization system is founded on this principle (17).
Potassium Chloride 186 mg
Calcium Carbonate 72 mg
These amounts can be topped up using ZONE CAPS™
The Bottom Line
•In a 4-8% solution (40-80 grams/litre), dextrose, sucrose, and amylopectin are well tolerated. Maltodextrin , if derived from dent corn, as most maltodextrin is, may be associated with incomplete digestion, contributing to bloating, flatulence, diarrhea and dehydration, due to the presence of maltodextrin chains that originated from the amylose portion of the original corn starch. Ask your manufacturer where their maltodextrin is derived from...
•The higher the glycemic index, the faster the carbohydrate fueling, and the more advantageous to the athlete.
•Osmolality is not an important concept if the drink is a 4-8% solution (40-80 grams/litre). Indeed, from a gastrointestinal tolerance viewpoint, the more important concept may well be the total GRAMS of carbohydrate in solution, not the osmolality.
•Dextrose facilitates sodium absorption in the small intestine, and reabsorption from the kidneys, and because of this, is the carbohydrate of choice for a drink in the heat where sodium balance is crucial.
•Maltodextrin (and other long chain carbohydrates like amylopectin) cannot be used in higher percent solutions to increase caloric density, even though osmolality may remain lower than comparable dextrose based solutions. Higher percent solutions of long chain carbohyrates are known to slow gastric emptying and are thought to leave short chain carbohydrate remnants undigested, depending on original source of these longer chains. This can contribute to bloating, flatulence, diarrhea and dehydration (46).
Carbohydrates supply much of the energy required to train and compete. Athletes can burn between 40-150 grams of carbohydrate per hour, depending on ambient temperature, sport, gender, body size, exercise intensity and many other factors. Our bodies do not store a lot of carbohydrate, so it is easy to deplete our carbohydrate reserves (carbohydrate is stored as glycogen, located in our muscles and liver). On average, our muscle cells store about 325 grams and our livers store about 110 grams of glycogen (18). Since each gram of carbohydrate has 4 Calories, this translates to about 1750 Calories - NOT MUCH! As these glycogen reserves start to deplete, which they can do within as little as 1 - 2 hours of strenuous exercise, blood sugar can start to fall (19), leading to several performance related problems including lack of energy, headache, dizziness and the dreaded "bonking" or "hitting the wall" (20, 21, 22). However, there is a caveat, namely that research has clearly shown that the higher the carbohydrate content of a drink, the slower its' emptying out of the stomach, and the more its' potential for causing stomach cramps and nausea (23). This appears to be the case, regardless of type of carbohydrate used (i.e. maltodextrin, dextrose, and any other carbohydrate in your drink) - the more carbohydrate in the drink, the slower it empties out of your stomach (42). Combine this with the fact that when pushing yourself in the heat, drinks that are too sweet can also promote nausea by sole virtue of their taste i.e. too syrupy, leaving a "pasty" mouth feel; therefore, a drink with too much carbohydrate can actually be detrimental to performance for many reasons. It turns out that the amount of carbohydrate for optimal gastric emptying lies between 4-8%, or 40-80 grams per liter (22, 24, 25, 26, 27). Again, this is regardless of the type of carbohydrate used. However, in practice, drinks with carbohydrate content above 5-6% can taste too sweet and syrupy when performing in the heat, contributing to nausea. In fact, one study defined this further by concluding that a 5.5% carbohydrate solution was optimal (28). Drinking a drink that is too sweet may be why you are diluting your current sports drink beyond the mixing instructions on the label. This dilution phenomenon compounds electrolyte problems even further, because now you are ingesting an even lower amount of electrolyte per liter of fluid. Therefore, a practical optimal range for carbohydrate is probably up to 6%, or 60 grams/liter, resulting in maximal gastric emptying, intestinal absorption, taste and subsequent fueling, and minimal "nausea factor" and "pasty" mouth feel.
e load™ weighs in at an optimal 5.4% carbohydrate (54 grams per litre). By comparison, fruit juices and cola drinks have between 10-15% carbohydrates (100-150 grams/liter), and some of today's sports drinks have up to 8% (80 grams/litre), or more, carbohydrate content! In the heat, carbohydrate content this high is much more likely to cause gastrointestinal upset.
Carbohydrate Crash Course
Biochemically, the majority of carbohydrates can be classified as mono-, di - or polysaccharides. Common examples of monosaccharides found in our diets include glucose (also called dextrose), fructose and galactose. When two monosaccharides are linked together via a chemical bond, a disaccharide is formed. For example, sucrose (table sugar) is made up of one glucose molecule linked to one fructose molecule; lactose (milk sugar) is made from one glucose molecule linked to one galactose molecule, while maltose (malt sugar) is formed from one glucose molecule linked to another glucose molecule. Polysaccharides (also called glucose polymers) are made of at least three monosaccharides linked together - some polysaccharides contain hundreds or thousands of monosaccharides. For example, starches, found in plant foods, are polysaccharides composed of many glucose molecules linked together. Starch comes in two forms - amylose, which is a straight chain of many glucose molecules, and amylopectin, which is a branched chain. Eighty-ninety percent of dietary starch is in the form of amylopectin. Animal polysaccharide is known as glycogen - this is the storage form of glucose in humans. Glycogen is also a series of glucose molecules linked together, and also contains branching of glucose molecules, more so than amylopectin. Breakdown products of digestion of polysaccharides include maltose (two glucose molecules), maltotriose (three glucose molecules) and alpha limit dextrins (such as maltodextrin), which are branched polysaccharides with an average of eight glucose molecules (see Pictorial Summary of Carbohydrates at the end of this section).
Carbohydrates commonly found in sports drinks include glucose (dextrose), sucrose, fructose, maltodextrin, amylopectin, amylose and high fructose corn syrup.
Digestion and Absorption
During exercise, for the most part, carbohydrates are broken down to their component monosaccharides during the process of digestion, resulting in release of fructose, galactose and mostly glucose (dextrose) in the small intestine. These sugars are then absorbed through the intestinal wall into the bloodstream, and then are taken to the liver. Glucose (dextrose) requires no processing, and is released into the bloodstream for use as quick energy Fructose and galactose are converted to glucose in the liver before they are released into the bloodstream. This process takes time, however, and therefore fructose and galactose are not ideal carbohydrates for use in sport, especially in the heat, where a steady supply of readily available carbohydrate is a must.
Furthermore, regarding fructose, this carbohydrate is a known irritant to the gastrointestinal tract (7). A lot of sports drinks and sports nutritional products contain this carbohydrate, contributing to gastrointestinal distress, especially in the heat.
Finally, some carbohydrates escape full digestion, passing into the large intestine. This contributes to flatulence, abdominal cramping and bloating. It can also cause diarrhea, and hence contribute to dehydration. The carbohydrates most likely to be associated with this phenomena are amylose, a plant based starch, and those derived from amylose, such as maltodextrin and glucose polymers.
Additional methods of carbohydrate classification are also used:
Simple or Complex?
Mono- and disaccharides are also classified as "simple" carbohydrates, and polysaccharides as "complex". This is an outdated mode of carbohydrate classification and there is currently no use for characterizing carbohydrates in this manner. This classification system has been replaced by Glycemic Index, discussed below.
High Glycemic Index (HGI) or Low Glycemic Index (LGI)?
This popular classification has been around for at least 20 years, and assesses the ability of the carbohydrate to elevate your blood glucose levels (glycemic response). The index uses either glucose (dextrose) or white bread as the standard to which all other carbohydrates and foods are compared. On their respective scales, glucose (dextrose) or white bread is assigned an arbitrary value of 100. Therefore, using glucose (dextrose) as a reference standard of 100, a carbohydrate resulting in 70% of the elevation in blood glucose would be assigned a value of 70. Glycemic response tests are done by ingesting 50 grams of the carbohydrate/food in question, and measuring the blood glucose level at two hours.
Many factors influence the glycemic index of a carbohydrate, and include size of the molecule, type of component monosaccharides, degree of thermal processing, contents/timing of the previous meal and the make-up of other co-ingested foods.
Because fructose and galactose must be converted to glucose by the liver first before they can elevate the blood glucose level, they have a low glycemic index i.e. this process takes time, resulting in slower increases in blood glucose. On a 100 point scale, fructose has a GI of 24, and galactose 22. These low GI scores mean that these substances are 'slow burn' carbohydrates. Use of these carbohydrates may lead to the body's overdependance on using its' glycogen stores, meaning eventual bonking. This concept is backed up by good research with respect to galactose, and the same problem can be reasonably inferred to exist with fructose (36).
Carbohydrates, especially in the heat, must be able to supply quick energy, so the closer to 100 on the GI scale, the better. All high GI carbohydrates are immediately available and ready to use by the body once absorbed because they require no processing in your liver, giving you the energy you need now to fuel performance; they are therefore also called 'fast burn' carbohydrates. Dextrose is certainly in this category and also has the benefit of being easy to digest and absorb, with no remnants passing into the large intestine. Polysaccharides like maltodextrin, glucose polymers and amylose also have GI scores around 100, but may be associated with incomplete digestion, as discussed above, a process potentially detrimental in the heat.
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.
Insulin and the Glycemic Index (GI)
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 (23).
Dextrose - e load™'s Choice
Based on the facts just mentioned, high GI, or "fast burn", carbohydrates, will not provoke an insulin response during exercise. Dextrose, a high GI carbohydrate was selected as e load™'s primary carbohydrate for several important reasons:
1.Great taste - dextrose is a mildly sweet carbohydrate that tastes pleasant, encouraging you to drink, but is not so sweet as to cause nausea (29), especially important in the heat.
2.No stomach and intestinal irritation - with dextrose, there is no stomach or intestinal irritation, especially important in the heat.
3.Rapid availability - guaranteed by its' high GI score of 100.
4.Facilitates sodium balance - dextrose facilitates absorption of sodium from your gut and reabsorption of sodium from your kidneys, important in helping to maintain normal sodium levels, crucial to performance in the heat (1, 2, 3, 4)? Dextrose is well known for these properties-no other carbohydrate is.
Additionally, where hypoglycemia is concerned, THERE IS NO ADVANTAGE GAINED BY USING low GI (slow burn) carbohydrates, BECAUSE INSULIN IS NOT SECRETED IN APPRECIABLE AMOUNTS DURING EXERCISE (23)!! THEREFORE, INGESTING DEXTROSE DURING EXERCISE CONFERS ON THE ATHLETE ALL OF THE POSITIVE BENEFITS OBTAINABLE FROM CARBOHYDRATES, INCLUDING RAPID ABSORPTION, NO GUT IRRITATION, ENHANCEMENT OF WATER AND SODIUM ABSORPTION, IMMEDIATE AVAILABILITY TO WORKING MUSCLE CELLS, LESS BONKING, ABILITY TO SUSTAIN HIGHER WORKLOADS, OVERALL GREAT TASTE AND NO CONCERN ABOUT DETRIMENTAL INSULIN INTERACTIONS!
Sweetening Your Drink
Sports drinks must be sweetened to enhance their taste. Currently, there are several ways to sweeten a drink:
These include Nutrasweet (Aspartame), Splenda™ (Sucralose) and Sweet One™/Sunette™ (Acesulfame K). At e load™, we don't like artificial sweeteners, for several reasons:
?They do not supply carbohydrate energy because they are not carbohydrates.
?Sucralose is not even absorbed into the body, and its presence in the gut in high concentrations may contribute to bloating, gas and diarrhea.
?The safety of both all of these products is still a concern in some circles.
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 (6, 7).
Sucrose is the logical choice for e load™. 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™ 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 sweetner 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 sweetners like aspartame, sucralose or acesulfame K in this regard.
There are several commonly used carbohydrates in sports drinks. These should be compared based on their effects on the following:
6.Post Exercise Glycogen Recovery
7.Effect on Fluid/Sodium Absorption
One of the reasons why a sports drink can be irritating to your gastrointestinal tract is its' acidity level. The standard measure of acidity is pH, and this number refers to the concentration of H+ or protons in the solution. The pH scale is an inverse scale ranging from 0 - 14, with numbers less than 7.0 being acidic, having more H+ than OH-, and vice versa for basic (alkaline) solutions with pH values above 7.0. The pH of distilled water is 7.0, having equal numbers of H+ and OH-, making it neutral. The ideal pH for any beverage is therefore 7.0.
Because the pH scale is logarithmic, a one unit change in pH is associated with a 10 fold change in the concentration of H+. For example, lemon juice has a pH of 2.0, while grapefruit juice has a pH of 3.0. Lemon juice would therefore be 10x the acidity of grapefruit juice. As another example, coffee has a pH of 5.0. Lemon juice would have 1000x the acidity of coffee (10 x 10 x 10).
Some ingredients used in sports drinks add acidity to the drink, including flavors and citric acid. Citric acid is a natural compound that helps control "tartness", and really does improve the palatability of most prepared drinks. Fortunately, e load™ has a relatively high pH (less acidic) than many sports drinks out there, and this is another reason why e load™ is very well tolerated by most who use it, especially in the heat. In fact, a drink like Gatorade has 35 times more acidity than e load™.
Based on these pH values, Gatorade has 35x more acidity, and Powerade has 52x more acidity, than e load™