14.7 - Hydration and Fluid Intake

Question 1

Temperature Regulation

Answer 1

• Proper water intake is vital during physical activity to regulate body temperature.
• The hypothalamus functions as the body’s thermostat.
• Temperature regulation involves two key cooling reflexes:
  
  • Dilation of blood vessels in the skin:
    
    • Increases blood flow to the surface to release heat.
  • Activation of sweat glands:
    
    • Produces sweat that evaporates, cooling the skin.

Question 2

Dehydration

Answer 2

• Dehydration occurs when fluid loss through sweating is not replaced.
• Impacts physical performance negatively.
• Fluid loss varies with:
  
  • Exercise intensity.
  • Environmental conditions.
• Additional water loss happens through:
  
  • Urination.
  • Feces.
  • Breathing.
• Regular fluid replacement is essential, especially during physical activity.
• Even slight body fluid declines can reduce performance.
• Hydration monitoring tip: Check urine color.

Question 3

Muscle Cramps, Heat Exhaustion, Heat Stroke

Answer 3

• Excessive fluid loss (dehydration) can cause dangerous conditions:
  
  • Muscle cramps:
    
    • Symptoms: Painful muscle twitches leading to full muscle cramps.
  • Heat exhaustion occurs when your body is unable to cool itself down properly:
    
    • Symptoms:
      
      • High body temperature.
      • Pale, cool, clammy skin.
      • Light-headedness.
      • Possible loss of consciousness.
  • Heat stroke (life-threatening):
    
    • Caused by a failure of the body’s heat-regulatory system.
    • Symptoms:
      
      • Very high body temperature.
      • Headache.
      • Confusion or behavioral changes.
      • Possible loss of consciousness.

Question 4

Appropriate Hydration and Rehydration

Answer 4

• Before Exercise:
  
  • Drink 2-3 cups of water 2-3 hours before.
  • Drink 1 cup 10-20 minutes before.
  • A meal with carbohydrates can also help.
• During Exercise:
  
  • For sessions under 90 minutes, drink water.
  • For longer sessions, drink a sports drink with 6-8% carbs and electrolytes.
  • Consume about 1/2 cup every 10 minutes, avoiding more than 60g of carbs per hour.
• After Exercise:
  
  • Rehydrate with fluids containing carbs and electrolytes.
  • Eat water-rich foods, like watermelon.
  • Drink 150% of the fluid lost during exercise (e.g., lose 2L → drink 3L).
• Importance:
  
  • Rehydration prevents dehydration and serious health issues.

Question 5

Hyponatremia

Answer 5

• Hyponatremia is a dangerous condition caused by consuming too much water during endurance events.
• It occurs when athletes lose electrolytes (especially sodium) through excessive sweating and drink large amounts of water, diluting the sodium in their blood.
• Common in recreational or novice athletes, especially in hot conditions.

Question 6

Body Mass Index – what is it? Equation?

Answer 6

BMI is widely used to assess the extent to which individuals are underweight or overweight. It is calculated as the ratio of a person’s weight to the square of his or her height:

BMI = weight (kg) / [height (m)]^2