SwimBikeRunStLouis

Super-Hydration

It's that time of year again when heat indices reach levels that are can be uncomfortable or outright hazardous for the unprepared.  The broken record litany of advice from our local weatherpersons regarding clothing and fluids is perhaps necessary, but tiresome.  Tell me something I don't already know.  How can I get an edge?

There has been research investigating the use of glycerol to assist athletes in storing heightened levels of water.  Does it work?  Why can't I just drink more water in the days leading up to an event?  Are there any adverse health effects to glycerol use?.

Exercising in heat and humidity for more than one hour can cause fluid loss in excess of 3 liters.  A 1.5 liter loss reduces performance by lowering the amount of blood delivery to active muscles.  It's possible to increase the amount of fluid in the body by drinking extra pre-event water, but the kidneys remove most of it within an hour.  Research suggests that glycerol added to fluids will increase blood volume, hydrate tissues, and delay fatigue associated with dehydration.

Glycerol dosage relates to the amount of total body water – so bigger people have more body water and require more glycerol to obtain an effect. Approximately 1 gram of glycerol per kilogram (2.2 lbs) of body weight is diluted in 20-25 milliliters of liquid. A 70 kg man (154 lbs), therefore, would need 70 grams of glycerol diluted in roughly 2 liters of fluid. The mixture should be consumed slowly over the course of 1-2 hours prior to exercise in the heat.  This, however, does not preclude the need to intake fluids during exercise.

Straight (undiluted) glycerin is not recommended for internal consumption, but no significant adverse side effects are associated with glycerin diluted with fluids  In some subjects, glycerol consumption may lead to headaches or nausea. Individuals in whom increased blood volume may be undesirable, including conditions such as pregnancy, high blood pressure, diabetes and kidney disease, should avoid glycerol supplementation.

In the face of positive results, there are lab studies that refute glycerol's performance enhancement property.  InterNutria believed enough to purchase patent rights early on from glycerol research pioneers and created Pro-Hydrator.  Other products have been developed as well.  GNC sells bottles of glycerol inexpensively over the counter  from which you can concoct your own mixture.

While there is still much research to be done on this front, I recommend you give it a shot during training and see if you can discern a difference.  Remember to keep the concentration light and to continue with normal hydration during exertion.  Maybe there is a way to beat the heat.

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