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[[File:Gels.JPG|right|thumb|300px|My supply of gels]]Understanding some of the science behind energy gels can help in [[Comparison of Energy Gels| evaluating and choosing the right gel]].=Carbohydrate Absorption =Maltodextrin There are three main components to the ease of absorption of a carbohydrate; how much water needs to be used to dilute it, how fast it gets into the blood and Sugarthe digestive path in the gut.==Required Dilution – Isotonic Drinks==A sport fuel is most easily absorbed when it is isotonicIsotonic drinks have a similar concentration (osmolality) of carbohydrate and electrolytes to the human blood and are easier to absorb<ref> http:name="isotonic"//jap.physiology.org/cgi/content/full/85/5/1941 Hypertonic solutions are less easily absorbed</ref>. The word isotonic means that there concentration is based on the same concentration number of molecules in rather than the fuel as in the bloodweight, so an isotonic drink with bigger molecules has more carbohydrate by weight. Most Gels are made from maltodextrin (sometime called maltodextrose), which [[Maltodextrin]] is a long molecule made up that is a chain of linked glucose. Because maltodextrin has larger molecules, so you can have a lot of it in an isotonic solution. Most Gels Maltodextrin is isotonic at 150g/500ml, where fructose, glucose and sucrose (table sugar) are close to isotonic without any significant dilutionat 26g/500ml. This means that you need to dilute the simple sugars with six times as much water as Maltodextrin . ==Absorption Rate - Glycemic Index=={{Main|Glycemic Index}}Glycemic index reflects how high a carbohydrate raises the blood sugar level. * Glucose is the standard against which everything else is measured, so it has a Glycemic Index of 100. Glucose is used because it raises the blood sugar faster than almost anything else. * [[Maltodextrin| Maltodextrin]] actually has a glycemic index of over 100, with values between 105 and 136. * [[Fructose| Fructose]] has a low glycemic index of 19, as it has to go via the liver to be converted to glucose. ==Digestive Path==While fructose has a low isotonic at 150g concentration and a low glycemic index, it can be absorbed via a different path (600 Calories[http://en.wikipedia.org/wiki/GLUT5 GLUT5])to glucose and Maltodextrin ([http://en.wikipedia.org/16 oz wiki/GLUT2 GLUT2]). This means that if you have enough glucose or 9gMaltodextrin to saturate that absorption path, adding fructose will improve the overall usage of the carbohydrate intake<ref name="Rowlands-2008"/>. ==Optimal Carbohydrate Intake==Most studies have shown that glucose and Maltodextrin can be absorbed and metabolized at up to 1.0 grams/minute, while Fructose is absorbed and metabolized at up to 0.6 grams/ozminute<ref name="maltoJeukendrup2004"/>. Gels are typically 25gCombining Fructose with glucose/Maltodextrin can result in the metabolism of up to 1.75 grams/minute<ref name="Jeukendrup2010"/1oz>. =Ingredient Analysis=Here is an analysis of the most common ingredients * '''Maltodextrin''' is the best form of carbohydrate, requiring only and provides the majority of carbohydrate in many gels. It has little or no flavor. * '''Glucose''' is easily digested, though not quite as easy as Maltodextrin. Glucose is about 74% as sweet as sugar (sucrose)<ref name="Sweetness"/>.* '''Fructose''' is useful as an equal quantity adjunct to Maltodextrin, but too much Fructose will cause digestive problems in many people. Fructose is 1.7x as sweet as table sugar<ref name="Sweetness"/>. * '''Sucrose '''(Sugar) is half glucose and half fructose joined together, but these components are split as part of liquid to dilutedigestion. This The word 'sugar' can be achieved using used to mean any type of sugar, but in general use it refers to Sucrose. Sometimes manufacturers try to conceal sugar in the ingredients by mixing referring to it as 'evaporated cane juice'. * '''Brown Rice Syrup''' is made by cooking rice with an enzyme to break down the gel starch. Brown ryce syrup is a mixture of 45% [http://en.wikipedia.org/wiki/Maltose maltose] (2 glucose molecules) and 52% [http://en.wikipedia.org/wiki/Maltotriose maltotriose] (3 glucose molecules) with saliva 3% as simple glucose. For practical purposes it can be considered the same as glucose, with an estimated Glycemic Index of around 85. However, there are concerns that organic brown rice syrup may be contaminated with arsenic<ref name="JacksonTaylor2012"/>. * '''Fat''' can make a gel more palatable and is consumeda useful fuel source at ultramarathon distances.* '''Protein''' can provide an additional fuel source and help limit the tendency of your body to cannibalize muscle for fuel. This makes * '''Amino acids''' may help performance, but the evidence is unclear at the levels provided in most gels very easily digested. A metric * '''[[Caffeine]] '''is great for how easily carbohydrates are digested improving performance and speeding the absorption of carbohydrate. * '''beta-Alanine''' is the Glycemic Indexan amino acid contained in Chia Surge. Most studies have shown that beta-Alanine will improve sprint performance<ref name="Hoffman-2008"/><ref name="Artioli-2010"/><ref name="Baguet-2010"/><ref name="Van Thienen-2009"/><ref name="Derave-2007"/>, with only one showing no benefit<ref name="Sweeney-2010"/>. Note that most studies used 2-6g/day of beta-Alanine, which is how much 4-12 packets of Chia Surge per day. Beta-Alanine may cause a harmless tingling of the skin<ref name="Artioli-2010"/>.=Reactive Hypoglycemia =In some people their blood sugar rises when will drop to lower than normal levels after a food is digested compared with glucose. Maltodextrin has high carbohydrate meal, a glycemic index condition known as Reactive Hypoglycemia<ref name="Brun"/>100.  Note that there are This condition effects some Gels that are athletes who take carbohydrate before exercise<ref name="Kuipers-1999"/>, but not maltodextrin basedif the carbohydrate is taken during the warm up<ref name="Brouns-1989"/> or immediately before exercise<ref name="Jeukendrup-2010"/>. It appears this hypoglycemia is specific to some individuals<ref name="Moseley-2003"/>. However, such as the old formula Clif Shots use brown rice syrupthere appears to be no performance impact from this hypoglycemia<ref name="Jeukendrup-2010"/> and I found no reports of hypoglycemia in response to carbohydrate taken during exercise. =Viscosity=Caffeine in [[File:Gel Viscosity.JPG|right|thumb|200px|The funnel and measure used to test the viscosity of gels.]]For the [[Comparison of Energy Gels]] the viscosity of gels was simplistically measured by measuring the time it takes for 5ml to flow through a funnel. The temperature for all tests was approximately 68f/20c. =Isotonic Calculations=Caffeine not only improves performanceFor those interested, it also increases there is the math behind the absorption isotonic calculations I use on my [[Comparison of Energy Gels| Comparison of Energy Gels]].* Blood has an osmolality of sugar from the gut280-330mOsm/kg, so it will make Gels quicker actingdrinks with a similar osmolality are considered Isotonic. * [[Maltodextrin]] is isotonic at 150g/500ml<ref name==Blood "malto"/>.** Therefore Maltodextrin requires ~3.3ml/g of water to be isotonic.* Fructose and glucose ** Fructose and glucose are both 180.16 g/mol.** 300 mmol of Fructose or glucose is therefore 54g (180.16 * 300 / 1000). ** 300 mOsm/kg is 54g/Kg or 26g per 500ml.** Therefore Fructose and Glucose require ~19ml/g of water to be isotonic.* Sucrose (table sugar )** Sucrose is the combination of one molecule of fructose with one of glucose.** Sucrose is 342.30 g/mol.** However, sucrose is decomposed into glucose and Insulinfructose before absorption<ref name==If you take "Gray1971"/>, so it has a gel similar isotonic concentration as fructose or other fast acting carbohydrate at restglucose.** Therefore Sucrose requires ~19ml/g of water to be isotonic.* Salt** Salt is sodium chloride (NaCl), which is 58.44 g/mol (Na:22.99 + Cl:35.45).** However, the sodium and chloride ions disassociate in water, your blood sugar will rise so 1 mole of NaCl you have 1 mole of Na and your pancreas will release insulin. Immediately after exercise1 mole of Cl, doubling the insulin will cause osmotic pressure.** 300 mmol of salt is 8.7g ((58.44/2) * 300 / 1000)*** 300 mOsm/kg is 8.7g/Kg or 4.4g per 500ml.** 1 gram of sodium implies 2.54g (1/22.99 * 58.44) of salt.** Therefore salt would require ~114 ml/g (500/4.4) of water to be isotonic** If you have just the sugar sodium value, either multiply by 2.54 to refuel get the musclesweight of salt, or use 290 ml/g of sodium.* Potassium** Potassium chloride (KCl), and at other times it will form fatwhich is 74.55 g/mol (K:39.10 + Cl:35.45). However** Like salt, during exercise potassium chloride disassociates in water. ** 300 mmol of salt is 11.2g ((74.55/2) * 300 / 1000)*** 300 mOsm/kg is 11.2g/Kg or 5.6g per 500ml.** 1 gram of potassium implies 1.9g (1/39.10 * 74.55) of potassium chloride.** Therefore potassium chloride would require ~89 ml/g (500/5.6) of water to be isotonic** If you have just the fast acting carbohydrate will be directly absorbed potassium value, either multiply by your muscles and not trigger insulin1.9 to get the weight of potassium chloride, or use 169 ml/g of potassium. ==References==