Some of this sounds way beyond what most of use would think of as common sense, but with the recent deaths of Korey Stringer of the Ravens, and other high school and college athletes, it seems like a good idea to repeat some of these hydration guidelines here.
- Drink before you feel thirsty.
- Consume at least 16 oz of fluid per hour of exercise
- If you want to know how much you are dehydrating, weigh yourself before and after exercise; the difference in weight is the amount of water you have lost. Take this water weight as a % of your body weight. You want to keep that number as low as you can.
- Drink a sports drink which contains both carbohydrate and sodium. Together they carry the fluid through your system faster, so you rehydrate faster.
- Avoid taking just water - it dilutes the electrolyte levels in your body which can prevent the absorption of fluids stopping you do from rehydrating as well.
- Avoid high calorie drinks like sodas if you want to rehydrate because they do not absorb as fast as drinks with lower particle density. You want to get the fluid absorption as fast as you can.
Water Basics - Water makes up about 60% of a young male's weight, and 50% of a female's. Two thirds of the water is held in our blood cells.. Hydration plays an vital role in regulating body temperature, energy metabolism and cardiovascular stress and plays a significant role in maintaining athletic performance levels.
Dehydration can be fatal if an athlete loses more than 9-12% of body weight through water loss. That means a 10 year old weighing 70 pounds would have to loose 7 pounds through water loss to suffer dehydration.
The Thirst Mechanism - In general we sweat out proportionately more water than minerals compared to the fluids in our body - we lose water at a faster rate. The concentration of sodium in sweat is about one third that of blood plasma. So as we sweat, the concentration of minerals in blood plasma may actually increase, which trigger's the body's thirst mechanism as it tries to maintain mineral balance. This thirst trigger mechanism is too slow and inefficient for hydration purposes and performance - by the time the body registers that it needs water for maintaining mineral balance, dehydration has already set in and performance will be declining.
Hydrate with more than just water - just drinking plain water when extremely dehydrated could tip the body the other way - if we were to quickly dilute the concentration of minerals in the vascular compartment of the body, we would excrete more water to maintain it, even if we were already dehydrated. So hydration has to be accompanied by the right blend of minerals - primarily sodium and chloride.