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Hydration

Fluids are a primary component of an athlete's diet.  Fluid replacement after exercise, and even on a regular basis is very important. We will be discussing when and what you should be drinking for an event.  Other topics about fluids will be discussed.

Roles of Water in the Body

The roles of water in the body are:

     1.  A component of all cells

     2.  Helps with the elimination of wastes

     3.  Protects some bodily tissues

     4.  Transports nutrients and gases

     5.  Maintenance of blood volume

     6.  Body temperature regulation

     1.  Long exposure to the sun

     2.  Hot air temperature

     3.  High relative humidity

     4.  Ground heat

Ways the body attempts to lose heat:

     1.  Sweat

     2.  Respiratory evaporation

     3.  Convection/conduction

     4.  Radiation from the body

***During cold weather, we lose more heat and sweat through respiratory evaporation.***

***During warm weather, we lose more heat and water through sweat.***

Ways to gauge fluid replacement:

  1.  Thirst

• by the time you are thirsty, you are already 2% dehydrated; not a reliable way to check hydration status

  2.  Body weight assessment

• for every 1 lb lost after exercise, you should drink 2 cups of fluid (at a minimum)

  3.  Urine excretion

• the urine should be pale in color if you are adequately hydrated

Some Fluid Replacement Concerns

  1.  You want gastric emptying to be quick

• temperature of the fluid
• colder fluids are emptied faster
• intensity of exercise
• moderate intensity increase the emptying, intense decreases it
• volume of fluid
• emptying is rather quick up to 2.5 cups of fluid
• CHO content
• slows down the emptying, but 6-10% CHO content is preferred when used

  2.  Intestinal absorption

  3.  CHO content

• only needed for events lasting longer than 90 minutes
• some types of CHO will be absorbed more quickly
• fructose is absorbed more slowly
• amount of CHO
• as previously mentioned, 6-10% will absorb quickly, but anything higher may cause g.i. problems

  4.  Palatability

• the better it tastes, the more you'll drink

  5.  Electrolytes

• they are lost in sweat
• usually are replaced from foods

Fluid Replacement Guidelines

Timing	Amount	Type of Beverage
Before Activity 1-2 hours 10-15 minutes	500 mL (16 oz) Up to 600 mL (20 oz)	Plain cold water Plain cold water, diluted fruit juice, glucose-electrolye drink
During Activity Every 10-15 minutes	150-250 mL (4-6 oz)	Plain cold water, glucose-electrolyte drink, diluted fruit juice
After Activity Begin immediately	Replace each pound of body weight lost with 500 mL (16 oz) of fluid	Plain water, sweet-tasting beverage

***Warmer fluids are appropriate when ambient temperatures are cool to cold.***

***Glucose and sodium are combined to promote rapid absorption from the small intestine.  Diluted fruit juice and electrolyte-glucse drinks may be best when you need fluids and energy immediately.  They will also help with endurance exercises lasting longer than 90 minutes.***

***Rule of thumb is to drink 6-8 cups daily plus 2 additional cups for every pound of body weight lost during exercise.***

Dehydration

Dehydration is also called hypohydration.  Some signs of hypohydration are:

     1.  Thirst

     2.  Loss of appetite

     3.  Lethargy

     4.  Anxiety

     5.  Nausea and Dizziness

     6.  Irritability

     7.  Cramps and Fatigue

     8.  Dark urine

     9.  Headache

Thirst is not a good way to judge hydration status.  The athlete may already be 1-2% dehydrated by the time they are thirsty.  It is believed that physical performance can be impaired at 3-4% dehydration. When we are talking about %'s, we mean how much water they are losing compared to their body weight.  1% dehydration means they have lost 1% of their body weight in water.

Here are some numbers that show what can happen to your body during hypohydration:

% Body Weight Loss

1%	Thirst
2%	Stronger thirst, vague discomfort and sense of oppression, loss of appetite
3%	Increasing hemoconcentration, reduction in urinary output, dry mouth
4%	Increased effort for physical work, flushed skin, impatience, sleepiness, apathy, nausea, emotional instability
5%	Difficulty in concentrating
6%	Impairment in exercise temperature regulation, increases pulse and respiratory rate
8%	Dizziness, cyanosis and labored breathing with exercise, indistinct speech, increasing weakness, mental confusion
10%	Spastic muscles, inability to balance with eyes closed, general incapacity, delirium and wakefulness, swollen tongue
11%	Cirulatory insufficiency, marked hemoconcentration and decreased blood volume, failing renal function
15%	DEATH

Hypohydration impairs the body's inability to dissipate heat and cause an elevated internal body temperature.  It may also decrease plasma volume, which is going to reduce the amount of oxygen being delivered to the muscles.  This may lead to a decrease in work capacity.  Since plasma volume may decrease, blood flow to the skin may also be decreased.  This will decrease the convective and evaporative heat dissipation, which also causes the internal body temperature to rise.  It is very easy to keep yourself hydrated.  Just carry a little water bottle around with you during the day and make sure that you drink a little throughout the day.  If you are going to be competing, make sure you consume a little more.  Water is cheap and very accessible so there is no reason that you should not be adequately hydrated on a daily basis.  

***Remember, caffeine and alcohol act as diuretics.  If you drank either one the night before or the day of, you should consume more fluids.  For each cup of coffee or ounce of alcohol, you should replace that with 1 cup of water, at a minimum.***

www.safecoinc.com/Gator/sod.html

www.cdc.net/~primus/fpc/fluids.htm

www.gatorade.com

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