It may seem obvious to drink during heavy physical activity. But many people underestimate the magnitude of their fluid loss. It is very difficult to avoid dehydration during a long race or when working in the heat because of the rate of sweat loss usually exceeds the rate of absorption of ingested fluids. The maximum rate of fluid absorption by the gastrointestinal tract during exercise is approx 800 ml (27 oz) per hour. The rate of fluid loss through seating can easily reach 1 liter (34 oz per hour and soar to 2 liters per hour under very strenuous conditions thus, it is not possible to drink enough to stay hydrated and dehydration will occur despite drinking plenty of fluid.
So guzzling a liter of water every hour, besides causing discomfort and bloating will not replenish lost liquids. Also, realize that the more dehydrated you get, the harder it is for your digestive tract to absorb what you drink.
In addition to the need to replenish lost water, you must also replenish lost electrolytes. An electrolyte deficiency can be just as dangerous as a water deficiency. Drinking only water, without a source of electrolyte, can dilute the remaining electrolytes in your bloodstream causing hyponatremia, low blood sodium.
Electrolyte deficiency can cause severe reactions, which can send you the hospital or even worse, during exercise, in the heat. More salt is lost in sweat per hour than is usually replaced by food and fluid by commercial sports drinks. Many athletes who rely solely on water and sport drinks for hydration are, to some level, prone to hyponatremia. It is estimated that up to 30% of the finishers of the Hawaiian Iron Man Triathlon are both dehydrated and hyponatromic. Ultra distance athletes have similar track record.
Sweat contains between 2.25-3.4 grams of salt (Sodium Chloride) per liter and the rate of perspiration during strenuous exercise can easily average 1 liter per hour. Experts recommended that during a long, hot race, you should aim for a total sodium intake of about 1 gram per hour. To get 1 gram (1000 mg) of sodium in your body, you would need to drink 2-1/2 liters (84 ounces) of Gatorade every hour! To get one gram of sodium from table salt, you would need to ingest 2.5 grams (1 gram from sodium and 15 grams from chloride). A teaspoon of salt weighs approx. 66 grams. So you would need to consume 3/8 teaspoon of salt with a liter of water every hour.
To make sure the salt and water are properly absorbed, the beverage also needs to contain 4-8% sugar. But the beverage should not be too sweet. Sugar levels above 10% are poorly absorbed and can cause diarrhea. Commercial beverage and sports drink come up short on sodium and often have too much sugar. Coconut water is a better option. Although 1 liter of coconut water may or may not a full gram of sodium, extra sodium can be added, if desired, either in the water or separately. In addition, coconut water also replenishes lost trace of minerals, has the proper sugar content for optimum absorption, supplies amino acids and other nutrients which may also support proper hydration and to top it off, tastes good!
Daniel Mondschain was introduced to coconut water while training for his 5th Marathon. He said "Coconut water improved my performance. At first. I drank it only after my runs. I realized I was recovering more quickly and with less soreness."
Impressed with the results, he began drinking coconut water instead of water or sports beverage during his workouts. He drank only coconut water throughout the final 2 months of training and during the marathon. The result? "I set a personal record and beat my last time by 7 minutes. I had more energy, less fatigue and less pain the final miles and that made me see the difference.
Coconut water is now a permanent fixture in his training regimen. Commercial sports drink contains water, sugar (sucrose syrup), yellow ft (a chemical dye), ester gum (a stabilizer to keep oils in suspension in water used mostly in making varnish and soap), and Brominated vegetable oils. Brominated Vegetable Oil is a vegetable that is chemically bonded to Bromine, an emulsifier used in citrus flavored drinks to help flavors stay suspended and produce the cloudy appearance. Bromine is a halogen that blocks Iodine utilization in the thyroid and other tissues in the body. The adverse effect is usually fatigue, headaches, tremors, memory loss, hallucinations and seizures.