Gatorade
Matt Hermes

Chemical Concepts
The formulation of Gatorade® depended on detailed consideration of the properties of near-isotonic solutions.

Try to relate these concepts to the relationship of exercise, dehydration and fatigue that we discuss in the accompanying unit.

Micro/Macro
and Symbolic
Representation
Chemistry uses macroscopic, large scale observations help describe and understand matter at the unseeable, microscopic level.

And then we represent both microscopic and macroscopic with often complex symbolic representations.

By determining the amount of fluid and salt loss, the inventors of Gatorade could begin to understand the macroscopic material balance in athletic performance. They would eventually relate that to the microscopic chemical reactions and physical transformations that were occuring.

Gatorade 10. Formulation of a Beverage

Dr. Cade and his research fellows at the University of Florida formulated a sports beverage based on the chemical principles of thermochemistry and osmotic behavior. 

Dr. Cade was trained as a nephrologist -- a physician specializing in the physiology of the kidneys. Kidneys manage fluids for the body, they maintain the proper concentration of components in the blood. The kidney is a chemical separation plant. Thousands of microscopic, semipermeable tubes (tubules) separate excess fluid as urine, carrying into the urine, salts and other chemical excretions. The concentration of chemicals in urine varies widely in normal kidney function. The organ keeps blood chemistry, the concentration of salts and sugars within the blood, stable within tightly-controlled, normal limits.

Back in 1965, Dr. Cade taught his students that uncontrolled fluid loss, such as that suffered in cases of extreme diarrhea, led to dehydration and dangerous salt depletion from the body. Excretory fluid that does not pass through the body's kidneys carries off essential salts, nutrients and water. He knew the dehydration of extreme diarrhea could not be reversed by forcing water on the patient. It was essential to also replenish the salts lost in uncontrolled fluid depletion.

It was easy enough for Dr. Cade and his three medical fellows, young physicians who had completed their medical residencies, to extend this thinking about excretions not passing the kidneys to the problems of athletes during exercise. You could weigh athletes before and after the stress of two-a-day summer football practices. An athlete can lose up to 7kg of mass on a long, hot day. Some of the weight loss is conversion of carbohydrates to carbon dioxide and water, followed by expiration of the CO2. The water leaves in respiration and in large volumes of perspiration -- up to 5 L.

The salt concentration of blood is about 9g/L.  The fluid that passes through the skin as sweat contains a lower concentration of salts.    But the five liters of fluid loss would cary away about 14 g of sodium chloride (2.8g/L). The concentration of the salt in the blood and remaining fluid in the body of the dehydrated athlete would rise. The kidneys would respond to the increased salt concentration by excreting a concentrated, dark-colored urine in order to decrease the salt content in the blood. This excretion would further dehydrate the athlete. And the common wisdom of the 1960s was that exercising athletes should take salt tablets. But they were not encouraged to drink fluids. The salt tablets simply deepened the problem. The salt drew fluid from the body into the intestines.

It seems like a simple problem, doesn't it?

If blocking and tackling on a hot Florida football field causes the players to dehydrate and the dehydration can lead to hyperthermia, why not just make them drink water, lots of water?

Dr. Cade's group understood this simple action didn't work. Trainers and coaches  seemed unable to get athletes to drink enough water. Coaches would plead or threaten but their athletes didn't drink enough and dehydrated in the afternoon sun.

Gatorade Label

Dr. Cade reasoned that a beverage combining fluid replacement and energy enhancement for the exercising person had to meet certain criteria: Provide water to replace lost fluid; Mimic the salt concentration of the body to replace lost salt; and Provide readily available fuel for continued work.

Dr. Shires recalls they had learned of new experimental work by Dr. Sid Malawer earlier in 1965. Successful researchers must know what's new in their field. They must read. They must talk with other scientists. Dr. Malawer told the Florida group he had studied the rate of absorption of water through the wall of the small bowel in human volunteers. (Fluid exchange occurs through the wall of the small bowel, not the stomach. The stomach serves only as a container.) Dr. Malawer's tests showed the fastest rate of transfer of water through the semipermeable membrane of the bowel occured with a solution that was isotonic -- had the same concentration of particles -- with the body. A solution of salts and glucose of the same concentration as the extracellular fluids showed the highest rate of uptake through the small bowel.