Water makes up 50-65% of total body weight and is essential for life. It performs many critical functions in the body like regulating temperature, aiding digestion, and transporting nutrients. The average adult loses 1,750-3,000 mL of water daily through the skin, lungs, urine, and feces. Proper hydration is important to prevent heat-related illnesses and impaired physical and mental performance. While most health experts recommend around 8 glasses of water per day, individual needs vary based on activity level and environmental conditions. Both overhydration and dehydration can be dangerous, so monitoring urine color is a good way to assess hydration status.

1. Unit 25 Water
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2. Water
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 50-65% of total body weight
 Survive 6 weeks or longer without food
 Survive only days without water
(approx. 6 days)
 WATER IS ESSENTIAL!

3. Functions of Water
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 Provide shape and structure to cells
 Regulate body temperature
 Aids in digestion and absorption
 Transports nutrients and oxygen into cells
 Eliminate waste products
 INVOLVED IN VIRTUALLY EVERY BODY
FUNCTION

4. Water losses
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 On average, adults lose approximately 1750 to 3000
mL of water daily
 Insensible water losses from the skin and expirations
account for approximately ½ of the total water lost
 Extreme environmental temperatures, high altitude,
low humidity, and strenuous exercise increase
insensible losses
 Water evaporation from the skin is also increased by
prolonged exposure to heated or recirculated air such
as during long airplane flights

5. Water and Fluoride
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 Water is a major source of fluoride
 Fluoride - formation and maintenance of enamel
and resistance to tooth decay
 Added to 70% of all municipal water supplies in US
 Not removed by filters

6. Water losses
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 Sensible water losses from urine and feces make
up the remaining water loss
 Because the body needs to excrete a minimum of
500 mL of urine daily to rid itself of metabolic
wastes, the minimum daily total fluid output is
approximately 1500 mL

7. Water Intake
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 35-55% consumed comes from tap/bottled water
 49-63% comes from other beverages
 19-25% comes from food

8. Water in Food
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 Fruits and vegetables
- made up of 70-90% water
 Meats
- made up of 50-70% water
 Most beverages
- made up of more than 85% water

9. Foods with High water content
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 Lettuce
 Watermelon
 Broccoli
 Carrots
 Grapes
 Tomatoes
 Oranges

10. Bottled vs. Tap Water
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 Both are regulated by the FDA
 25% of bottled water is actually tap water
 “Enhanced” waters are more commercial than
nutritional

11. Plastic Bottles and BPA
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 Certain types of plastics contain BPA (bisphenol A)
 Softening compound that makes plastic flexible
 Released when plastic is heated
 Similar shape to estrogen
 May be linked to increased risk :
- reproductive problems
- heart disease
- diabetes
- behavior changes

12. How much do we need?
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 Men AI = 3.7 L per day (approx. 15 cups)
- 3 L coming from water and beverages
 Women AI = 2.7 per day (approx. 11 cups)
- 2.2 L coming from water and beverages
 8 glasses a day???
- most do not consume this amount
- no scientific evidence that increased intake increases
health

13. How do we know if we’re getting enough?
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 Thirst – poor indicator of hydration status – may be
2-3% dehydrated before you feel it
 Urine color – pale yellow – like lemonade

14. Fluids That Don’t Hydrate
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 Fluids with >8% carbohydrates can increase
dehydration
- can also draw water in the stomach, causing
fullness and cramping
 Alcoholic beverages are not hydrating
- diuretic
- *Beer is used after some marathons for CHO
 In a sodium-depleted person, water is not hydrating

15. Carbohydrate and Sodium Contents
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16. Estimating Fluid Needs During
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Exercise
 Sweat rate
- Fluid loss per hour of exercise
- Sum of body weight loss plus fluid intake
 Calculate sweat rate:
- Weigh yourself 1 hour before/after workout
- Subtract post-workout weight from pre-
- 1 pound lost = 16 oz

17. Inadequate Intake of Water
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 Dehydration
 Impaired mental function
 Impaired motor control
 Increased HR
 Unresolved dehydration can lead to kidney failure
and even death

18. Consequences of Dehydration
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 Dehydration:
- Loss of more than 2% of body weight (2-4 pounds)
during an event
- Impairs performance
- Can lead to heat exhaustion or heat stroke

19. Heat Exhaustion
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 Caused by  body H2O & Na due to
excessive loss of water through sweat
in hot weather
 Symptoms:
- intense thirst - weakness
- paleness - dizziness
- nausea - fainting
- confusion
 Remedy: fluids w/ electrolytes & rest in
a cool place

20. Heat Stroke
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 Requires emergency  Body temp. > 105° F
medical care - breakdown of
 Characterized by: mechanisms that regulate
- hot, dry skin body temp.
- labored, rapid breathing
- rapid pulse  AKA sunstroke
- nausea
- blurred vision  Caused by prolonged
- irrational behavior exposure to environ. heat
- coma or strenuous activity

21. Signs of Dehydration
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 Thirst
 Lightheadedness or fatigue
 Headache or inability to concentrate
 Feeling cold or chills in hot weather
 Collapse due to heat exhaustion or heat stroke
 Producing small amounts of dark-colored urine

22. Hyponatremia and Athletes
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 Hyponatremia
- Low blood sodium
- Life-threatening condition in marathon runners
- Caused by consuming large amounts of water
without sodium during an endurance event
- Causes difficulty breathing, bloating, confusion,
nausea, vomiting, swelling around brain

23. Water Intoxication
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 Too much water – hyponatremia
– dilute constituents in blood
- causes imbalances of water
and electrolytes
– rare
 Symptoms:
- confusion - headache
- vomiting - seizure
- coma - death

24. Water Intoxication
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 Can lead to death
 Jennifer Strange
“Hold your wee for a wii”
Drank 2 gallons of water
Died 6 hours later
Video
 Radio station was held
accountable for her death