This presentation is about the need and importance of water in out daily consumption especially for athletes before, after and during exercise. it also discusses its functions
2. โWhile it is possible to live for
several weeks or even months
without food, our bodies can feel
the effects of water deprivation
within as little as 30 minutes.โ
Water Balance
3. Water comprises 60-70% of body weight
โข Gives structure to cells
โข Body Fluids:
โ saliva, blood, digestive juices, etc.
โข Solvent for nutrients and waste products;
transport of these
โข Padding/lubrication:
โ joints, spinal cord, GI tract
โข Thermoregulation
4. โข Intracellular water (~2/3)
โ inside cells
โข Extracellular water (~1/3)
โ interstitial (between and around cells)
โ in blood
5. Water weight varies with body composition:
โข 1g protein (lean tissue) is associated with
โข 3g water
โข 1g glycogen โ
โข 1g fat โ
6. So lower body fat and higher
muscle/glycogen
โขLow kcal/low CHO diet
โข decreased glycogen stores (metabolized for
energy)
โข decreased body protein (metabolized for
energy or gluconeogenesis)
โข weight loss from decreased body water
7. Water Balance
โข Water โinโ
โ water in food, beverages, and water produced
during metabolism of food
โข Water โoutโ
โ skin, urine, feces, lungs
During heavy exercise: losses up to 4 lb/hour
possible
Thermoregulation is affected after:
8. Electrolytes
โข Charged atoms (ions) that conduct electrical
current
โข Involved with fluid balance:
โ Sodium (Na+) extracellular fluid
โ Potassium (K+) intracellular fluid:
important in:
โข the generation of electrical impulses to nerves
โข muscle contraction
โข transport of glucose into the muscle cells
โข glycogen storage
9. Electrolytes
โข Chloride (Cl-) major negative ion in both
body fluids and in foods.
โข Works w/Na+ in the regulation of both
acid-base balance and fluid balance.
11. Regulation of Body Water
โข Osmotic pressure:
โ membrane with solution on either side (intra- and
extracellular water)
โ Water can pass through freely, but not solutes
โ The concentration differs according to the # of
particles per unit volume
โ Water is drawn from the compartment with low
concentration to the one w/ high concentration
12.
13. Factors affecting water balance
โข Diuretic: substance that causes the body to
excrete water
โ
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โ
14. Factors Affecting Water Balance
โข ADH: Anti-diuretic Hormone
โ Secreted when blood concentration of ions rises
โ
โข Thirst:
15. RDA for Water
โข 1 ml/ kcalorie expended
โ (your kcals = your ml water recommended via
food and liquids)
16. Thermoregulation
โข Water absorbs heat from muscles ๏ blood to
skin ๏ blood cooled by evaporation of sweat.
โ humidity: less evaporation of sweat/higher body
temp.
โ hot, dry climate: more sweat/water loss
โข Excessive body temperature:
โ nausea, dizziness, cramps (heat exhaustion)
โ can ๏ heat stroke (can be fatal)
17. Exercise and Water Balance
โข During exercise: water lost through breathing and
sweat
โข Effects of a 1% body weight water loss:
โ
โ
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โ risk of injury
18. Signs of Dehydration
Mild Dehydration
โข Thirst
โข Sudden wt. Loss
โข Dry mouth, throat,
body linings
โข Rapid pulse
โ โ B.P.
โข Weakness
โข Dark, infrequent
urination
Severe Dehydration
โข Pale skin
โข Bluish lips and
fingertips
โข Confusion
โข Rapid, shallow
breathing
โข Weak, rapid, irregular
pulse
โข Shock; seizures
โข Coma; death
19. โข During exercise, sodium and chloride are lost in
sweat
โข But, kidneys respond by reabsorbing more Na+
and Cl-
โข Unnecessary to supplement in most cases (too
much K+ can be dangerous)
โข Losses of Na, K, calcium magnesium and
phosphorus are easily replaced in the diet
โข Sports drinks supply electrolytes in the event of
heavy losses
21. Preventing dehydration:
โข Before exercise:
โ 7ml/kg (~1 oz/10lb) water or sports drink about 2
hours before exercise
โข More for profuse sweaters: weigh pre- and post-
training session
โ kidneys need 90 min to process fluids
โ then 1-2 cups a few minutes prior to exercise
โ cold beverages are absorbed more quickly
22. โข During exercise
โ Donโt rely on thirst alone (mechanism blunted during
ex)
โ Drink early and regularly
โ Fluid replacement enhances performance
23. โ
โ 1 - 1.5 cups fluid every 15 to 20 minutes during
endurance activity to keep gastric emptying up.
24. Sports Drink
โข contain CHO to help maintain glycogen
โข more than 8-10% CHO
โ water drawn osmotically into the intestine
โ bloating, cramping, and diarrhea (osmosis)
25. Sports Drink
โข 6-8% CHO solution is best (most sports
drinks)
โ encourages more consumption and is
absorbed quickly (12-20g CHO/cup)
โ fruit juice diluted 1:2 with water
โข Glucose polymers in sports drinks are
quickly absorbed
โข Exercise >60 min, CHO drinks enhance
endurance
26. After exercise:
โ CHO repletion after exercise to replete glycogen:
1g/Kg within first 2 hours, then high CHO diet
thereafter (65-70%)
โ Post exercise fluids should be high glycemic index
fluids (low fructose)
โ Protein-CHO combination may increase glycogen
re-synthesis (3g CHO:1g prot)
โ Salt supplement tablets are not generally
recommended (gastric irritation and excess fluid
retention)
Thermoregulation (and exercise performance) is affected after 1% body wt (1.6 lb for a 160 lb person)
Water dissolves salts and follows electrolytes
Major role of Na and K is to maintain fluid balance through osmotic pr.
Water moves from low to high concentration in an effort to โdiluteโ the side w/high concentration.
Maintenance of equal conc. is important: too much water into cell ๏ burstโฆ too little, โdeflate.โ Remember water is the medium for all these chemical reactions.
--high protein diet (excess urea produced must be diluted to remove it from the blood and excrete it through the kidneys)
ADH: (vasopressin -- made in the hypothalamus) action on kidneys to retain body water
levels increase when conc. of ions rises (dehydration)
--high protein diet (excess urea produced must be diluted to remove it from the blood and excrete it through the kidneys)
ADH: (vasopressin -- made in the hypothalamus) action on kidneys to retain body water
levels increase when conc. of ions rises (dehydration)
decreased blood volume (lowers nutrient supply to cells)
Small amounts of electrolytes in sports drinks are more than adequate for heavy exercisers where several pounds of fluid are lost day after day.
also can cause reactive hypoglycemia due to insulin response
also can cause reactive hypoglycemia due to insulin response
Exercising in a different climate (hotter, colder, more humid, high elevation) over 5-10 days allows the body to adjust to changes
increased capacity for sweating (to better cool the exercising body)
What do you think about โgoing flat?โ Body builders consider dehydrating themselves to make their vascular looking muscles look โflat.โ Low CHO diet to deplete glycogen and ๏ dehydration.