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==Digestive Path==
While fructose has a low isotonic concentration and a low glycemic index, it can be absorbed via a different path ([http://en.wikipedia.org/wiki/GLUT5 GLUT5]) to glucose and Maltodextrin ([http://en.wikipedia.org/wiki/GLUT2 GLUT2]). This means that if you have enough glucose or Maltodextrin 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/minute<ref name="Jeukendrup2004"/>. Combining Fructose with glucose/Maltodextrin can result in the metabolism of up to 1.75 grams/minute<ref name="Jeukendrup2010"/>.
=Ingredient Analysis=
Here is an analysis of the most common ingredients
=Reactive Hypoglycemia =
In some people their blood sugar will drop to lower than normal levels after a high carbohydrate meal, a condition known as Reactive Hypoglycemia<ref name="Brun"/>. This condition effects some athletes who take carbohydrate before exercise<ref name="Kuipers-1999"/>, but not if 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, there 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=
[[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=
For those interested, there is the math behind the isotonic calculations I use on my [[Comparison of Energy Gels| Comparison of Energy Gels]].
** Therefore potassium chloride would require ~89 ml/g (500/5.6) of water to be isotonic
** If you have just the potassium value, either multiply by 1.9 to get the weight of potassium chloride, or use 169 ml/g of potassium.
=References=
<references>
<ref name="JacksonTaylor2012">Brian P. Jackson, Vivien F. Taylor, Margaret R. Karagas, Tracy Punshon, Kathryn L. Cottingham, Arsenic, Organic Foods, and Brown Rice Syrup, Environmental Health Perspectives, volume 120, issue 5, 2012, pages 623–626, ISSN [http://www.worldcat.org/issn/0091-6765 0091-6765], doi [http://dx.doi.org/10.1289/ehp.1104619 10.1289/ehp.1104619]</ref>
<ref name="Sweetness">Sweetness http://biology.clc.uc.edu/courses/bio104/carbohydrates.htm</ref>
<ref name="Jeukendrup2004">Asker E Jeukendrup, Carbohydrate intake during exercise and performance, Nutrition, volume 20, issue 7-8, 2004, pages 669–677, ISSN [http://www.worldcat.org/issn/08999007 08999007], doi [http://dx.doi.org/10.1016/j.nut.2004.04.017 10.1016/j.nut.2004.04.017]</ref>
<ref name="Jeukendrup2010">Asker E Jeukendrup, Carbohydrate and exercise performance: the role of multiple transportable carbohydrates, Current Opinion in Clinical Nutrition and Metabolic Care, volume 13, issue 4, 2010, pages 452–457, ISSN [http://www.worldcat.org/issn/1363-1950 1363-1950], doi [http://dx.doi.org/10.1097/MCO.0b013e328339de9f 10.1097/MCO.0b013e328339de9f]</ref>
<ref name="Van Thienen-2009"> R. Van Thienen, K. Van Proeyen, B. Vanden Eynde, J. Puype, T. Lefere, P. Hespel, Beta-alanine improves sprint performance in endurance cycling., Med Sci Sports Exerc, volume 41, issue 4, pages 898-903, Apr 2009, doi [http://dx.doi.org/10.1249/MSS.0b013e31818db708 10.1249/MSS.0b013e31818db708], PMID [http://www.ncbi.nlm.nih.gov/pubmed/19276843 19276843]</ref>
<ref name="Hoffman-2008"> JR. Hoffman, NA. Ratamess, AD. Faigenbaum, R. Ross, J. Kang, JR. Stout, JA. Wise, Short-duration beta-alanine supplementation increases training volume and reduces subjective feelings of fatigue in college football players., Nutr Res, volume 28, issue 1, pages 31-5, Jan 2008, doi [http://dx.doi.org/10.1016/j.nutres.2007.11.004 10.1016/j.nutres.2007.11.004], PMID [http://www.ncbi.nlm.nih.gov/pubmed/19083385 19083385]</ref>