1. Water comprises 60-70% of the human body and is essential for many bodily functions like structure, transport, and thermoregulation. 2. During exercise, water is lost through sweat and breathing which can lead to dehydration if fluid intake is inadequate. Even mild dehydration of 1% body weight loss can negatively impact performance. 3. To prevent dehydration, it is important to drink fluids regularly before, during, and after exercise to replace water and electrolyte losses and maintain proper hydration.

1. WATER BALANCE AND
EXERCISE PERFORMANCE
BY
Dr.Ahmed Mohamed Mostafa
LECTURER OF PHYSICALTHERAPY FOR PEDIATRICS
FACULTY OF PHYSICALTHERAPY
MERIT UNIVERSITY.

2. “While 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.”

3. • Water comprises 60-70% of body weight
1. Gives structure to cells
2. Body fluids: saliva, blood, digestive juices, etc.
3. Solvents for nutrients and waste products; transport of these
4. Padding/lubrication: joints, spinal cord, GI tract
5. Thermoregulation

4. •Intracellular water (~2/3) inside cells
•Extracellular water (~1/3)
1. Interstitial (between and around cells)
2. In blood

5. •Water weight varies with body composition:
1. 1g protein (lean tissue) is associated with 3g water
2. 1g glycogen
3. 1g fat

6. So lower body fat and higher muscle/glycogen =
increased water content
Low kcal/low CHO diet
• Decreased glycogen stores (metabolized for energy)
• Decreased body protein (metabolized for energy or
gluconeogenesis) •
• Weight loss from decreased body water

7. Water Balance
• Water “in” water in food, beverages, and water
produced during the metabolism of food
• Water “out” skin, urine, feces, and lungs
•During heavy exercise: losses up to 4 lb/hour possible
•Thermoregulation is affected after

8. Electrolytes
• Charged atoms (ions) that conduct electrical current
• Involved with fluid balance:
- Sodium (Na+) extracellular fluid
- Potassium (K+) intracellular fluid: important in:
1. The generation of electrical impulses to nerves
2. Muscle contraction
3. Transport of glucose into the muscle cells
4. Glycogen storage

9. Electrolytes
• Chloride (Cl-) major negative ion in both body fluids and
in foods.
- Works with Na+ in the regulation of both acid-base
balance and fluid balance.

10. Water dissolves salts and
follows the electrolytes

11. Regulation of Body Water
•Osmotic pressure:
- Membrane with a solution on either side (intra- and extracellular
water)
- Water can pass through freely, but not solutes
- The concentration differs according to the # of particles per unit
volume
- Water is drawn from the compartment with a low concentration to the
one with a high concentration

12. Factors affecting water balance
• Diuretic: a substance that causes the body to excrete water
•ADH: Anti-Diuretic Hormone: Secreted when blood
concentration of ions rises
• Thirst

13. Recommended Dietary Allowances (RDA)
or Dietary Reference Intake for Water
1 ml/ kcalorie expended
(your kcals = your ml water recommended
via food and liquids)

14. Thermoregulation
• Water absorbs heat from muscles ----> blood to skin -----> blood
cooled by evaporation of sweat.
- Humidity: less evaporation of sweat/higher body temp.
- Hot, dry climate: more sweat/water loss
• Excessive body temperature:
- nausea, dizziness, cramps (heat exhaustion)
- can -----> heat stroke (can be fatal)

15. Exercise and Water Balance
•During exercise: water lost through breathing and
sweat
• Effects of a 1% body weight water loss:
•More than these → Increase risk of injury

16. During exercise
• Sodium and chloride are lost in sweat
• But, kidneys respond by reabsorbing more Na+ and Cl-
• Unnecessary to supplement in most cases (too much K+ can be
dangerous)
• Losses of Na, K, calcium magnesium, and phosphorus are easily
replaced in the diet
• Sports drinks supply electrolytes in the event of heavy losses

17. • Mild Dehydration
- Thirst
- Sudden wt. Loss
- Dry mouth, throat, body linings
- Rapid pulse
- Decrease B.P.
- Weakness
- Dark, infrequent urination
•Severe Dehydration
- Pale skin
- Bluish lips and fingertips
- Confusion
- Rapid, shallow breathing
- Weak, rapid, irregular pulse
- Shock; seizures
- Coma; death
Signs of Dehydration

18. Preventing dehydration
•Consume adequate fluids daily
- Clear urine every 2-4 hours
Dark-colored, infrequent urination indicates dehydration

19. Preventing dehydration
•Before exercise:
- 7ml/kg (~1 oz/10lb) water or sports drink about 2 hours before exercise
➢More for profuse sweaters: weigh pre- and post-training session
- Kidneys need 90 min to process fluids
- Then 1-2 cups a few minutes prior to exercise
- Cold beverages are absorbed more quickly

20. •During exercise:
- Don’t rely on thirst alone (mechanism blunted during ex)
- Drink early and regularly
- Fluid replacement enhances performance
- 1 - 1.5 cups fluid every 15 to 20 minutes during endurance activity
to keep gastric emptying up

21. •Sports Drink
- Contain CHO to help maintain glycogen
- More than 8-10% CHO
➢Water is drawn osmotically into the intestine
➢Bloating, cramping, and diarrhea (osmosis)
- 6-8% CHO solution is best (most sports drinks)
➢Encourages more consumption and is absorbed quickly (12-
20g CHO/cup)
➢Fruit juice diluted 1:2 with water
- Glucose polymers in sports drinks are quickly absorbed
- Exercise >60 min, CHO drinks enhance endurance

22. • After exercise:
- CHO repletion after exercise to replete glycogen: 1g/Kg within first 2
hours, then high CHO diet thereafter (65-70%)
- Post-exercise fluids should be high glycemic index fluids (low
fructose)
- Protein-CHO combination may increase glycogen re-synthesis (3g
CHO:1g prot)
- Salt supplement tablets are not generally recommended (gastric
irritation and excess fluid retention)

23. Acclimatization
•Exercising in a different climate over 5-10 days
•Regular exercise also produces acclimatization-type
effects