Unit 25 Water1

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Water

50-65% of total body weight

Survive 6 weeks or longer without food

Survive only days without water(approx. 6 days)

WATER IS ESSENTIAL!

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Functions of Water

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

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Water losses

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

Water and Fluoride

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

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Water losses

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

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Water Intake

35-55% consumed comes from tap/bottled water

49-63% comes from other beverages

19-25% comes from food

Water in Food

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

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

Bottled vs. Tap Water

Both are regulated by the FDA

25% of bottled water is actually tap water

“Enhanced” waters are more commercial than nutritional

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Plastic Bottles and BPA

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

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How much do we need?

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

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How do we know if we’re getting enough?

Thirst – poor indicator of hydration status – may be 2-3% dehydrated before you feel it

Urine color – pale yellow – like lemonade

Fluids That Don’t Hydrate

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

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Carbohydrate and Sodium Contents

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Estimating Fluid Needs During 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

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Inadequate Intake of Water

Dehydration

Impaired mental function

Impaired motor control

Increased HR

Unresolved dehydration can lead to kidney failure and even death

Consequences of Dehydration 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

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Heat Exhaustion

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

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Heat Stroke

Body temp. > 105° F- breakdown of mechanisms that regulate body temp.

AKA sunstroke

Caused by prolonged exposure to environ. heat or strenuous activity

Requires emergency medical care

Characterized by:- hot, dry skin- labored, rapid breathing- rapid pulse- nausea- blurred vision- irrational behavior- coma

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Signs of Dehydration

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

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Hyponatremia and Athletes

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

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Water Intoxication

Too much water – hyponatremia – dilute constituents in blood- causes imbalances of water

and electrolytes – rare

Symptoms:- confusion - headache

- vomiting - seizure - coma - death

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Water Intoxication

Can lead to death

Jennifer Strange“Hold your wee for a wii”Drank 2 gallons of waterDied 6 hours later

Radio station was held accountable for her death

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Video