1. How much did you drink at the weekend?

2. Fluids and Hydration Applying the Principles of Nutrition to a Physical Activity Programme

3. Learning outcomes Describe the main function of water
List the ways in which the body loses fluid
State how much water is needed per day
Describe the potential consequences of dehydration
Describe how to assess hydration levels
Explain the effect of solute (sugar) and electrolyte (sodium) content on water absorption across the gut by osmosis
Describe the composition of hypertonic, hypotonic and isotonic sports drinks and discuss their uses.
Evaluate the effectiveness of different drinks as re-hydrators
Discuss the diuretic effect of caffeine, alcohol and high-sugar drinks
Describe current guidelines (Department of Health) for safe upper limits of alcohol per day
State the energy value of alcohol

4. Functions of water Water accounts for 60-70% of our body
Transport system for nutrients
Removes waste products
Temperature regulation
Environment where chemical reactions occur

5. How is fluid lost from the body
Water loss occurs continuously:
Breathing
Sweating
Excretion of waste
Typically 2.5 litres per day
Water input needs to match water loss – otherwise dehydration occurs

6. Water intake Water can be derived from food and fluids consumed
A well-balanced diet can provide 1 – 1.5 litres of water just from food.
The rest must come from fluids
Individual requirements vary depending on energy expenditure, temperature, body size, etc.

7. Consequences of dehydration
Decrease in blood volume/blood pressure thus compromising distribution of nutrients and oxygen around the body.
Decreased blood flow to the brain therefore headache, poor concentration and compromised motor fitness.
Decrease in kidney function because of water retention
Decrease in metabolic rate in all cells with consequences for metabolic efficiency and weight management
Increased risk of poor digestion and constipation

8. How to assess hydration levels Urine colour hydration level
Clear: Hydrated
Very pale yellow (straw): Hydrated
Pale yellow: Hydrated
Yellow Mild: Dehydration
Dark yellow: Dehydration

9. How fluids enter the blood
Fluids move across the intestinal wall by osmosis – movement from a high to low concentration of molecules (sugar and salt) they contain
Sugar = ‘solute’
Salt/sodium = ‘electrolyte’
Fluids can be categorised in relation to their ‘osmolality’ – depending upon their sugar and sodium content

10. Sports drinks
Sports Drinks fall into three categories based on their osmolality:
Hypertonic
Isotonic
Hypotonic
Mainly depends on their sugar content

11. Hypertonic Contains more sugar than body fluids 8g(or more)/100mls
Water moves into the gut to dilute it before it can be absorbed
Useful in providing fuel for exercise
Inefficient at providing hydration
Fruit juice, fizzy drinks, energy drinks
Over consumption can lead to tooth decay

12. Isotonic
Contains the approximately the same concentration of sugars as body fluids
Between 4 – 8g/100mls
Absorption from gut is slightly faster than plain water, giving to fast hydration
Useful during exercise as a small amount of energy is also supplied

13. Hypotonic Contains less sugar than body fluids 4g(or less)/100mls
Absorption from gut is slightly faster than plain water, giving to fast hydration
Less useful during exercise as only a very small amount of energy is supplied

14. Stimulates the kidneys to excrete more fluid
Diuretics
Stimulates the kidneys to excrete more fluid
Caffeine (coffee, tea, cola, energy drinks, etc.)
Alcohol
High sugar content
Can accelerate dehydration

15. Department of Health: ‘safe upper limits’
Recommended guidelines for safe alcohol consumption
Department of Health: ‘safe upper limits’
Males
Females
Per Week
21 Units
14 Units
Per Day
3 – 4 Units
2 –3 Units

16. ½ pint of lager at 3.5% alcohol 25mls spirits at 40% alcohol
Recommended guidelines for safe alcohol consumption
You should not ‘save up’ your recommended units and consume them all in one day.
What is a unit?
½ pint of lager at 3.5% alcohol
25mls spirits at 40% alcohol
125mls wine at 9% alcohol

17. Energy value of alcohol
1g (or 1ml) of alcohol contains 7kcal