Easy to digest information on the importance of hydration in sport, the physiological effects of dehydration on performance, the role of sports drinks as an ergogenic aid!

1. Sports Nutrition
BTEC L3 Sport
Gatorade!

2. Learning Outcomes
Students shall develop knowledge of hydration
and sports drinks.
Students shall learn how to calculate sweat rates
and dehydration status.
Students shall learn how to make their own sports
drinks.

3. Hydration – Key Terms
Thermoregulation
“ The ability to keep the body’s temperature
constant, even if the surrounding temperature is
different.”
Ergogenic Aid
“a substance that improves exercise performance.”

4. Functions of Water (H20)
Eliminates waste products (urine, faeces)
Transport materials around the body
Regulate body temperature (thermoregulation)
Cushion joints – how?
Keeps skin moist
(the worlds cheapest and most effective beauty treatment)
Fact!
brains are 75% water.
bones are 25% water.
blood is 83% water.

5. Water
Main transport mechanism - carries nutrients and waste
products
Vital for thermoregulation
Aids the passage of food through digestive system
Water makes up approx. 60% of your total body weight,
(this depends on age, sex and body composition).
A human contain 30-50 litres of H2O!
Fact!
Leaner individuals contain more
water than fatter people of the same
mass.....

6. Average fluid balance values for humans
Water Input Water Output
Source ml Source ml
Fluids 1,200 Urine 1,250
Food 1,000 Skin 850
Metabolism 350 Lungs 350
Faeces 100
Total 2,550 Total 2,550

7. De-hydration
Hinders performance by affecting strength, power,
coordination and aerobic endurance, (virtually all CoF’s!)
Severe dehydration can cause heat stroke and can be fatal!!!
Signs & Symptoms
Lack of energy and early fatigue during exercise
Feeling hot
Clammy or flushed skin
Not needing to go to the toilet
Headache
Disorientation
Shortness of breath
Poor performance (mental & physical)

8. Hydration Terminology
De-hydration
Excessive loss of water from the body
Re-hydration
Replacing fluids lost through exercise.
Hypo-hydration
In a state of decreased hydration, less than normal water content in
the body, (impairs thermoregulation).
Hyper-hydration
Increased hydration from normal (can improve thermoregulation).
Super-hydration
A state hydration achieved by manipulation with the ergogenic aid
glycerol, (glycerol has shown to increase water retention). A strategy
to reduce heat stress in hot environments

9. Adverse effects of dehydration
1% - Threshold of Thirst.
2% - Stronger thirst, discomfort, loss of appetite,
impaired performance.
3% - Dry mouth, decrease in blood plasma and
urinary output.
4% - 20-40% decrease in work capacity
(max. physical work).
5% - Impaired concentration, headache, impatience,
sleepiness/drowsiness.
6% - Severe impairment of thermoregulation during
exercise, increased heart rate.
>7% Collapse, dizziness, loss of balance,
delirium, exhaustion.
10%+ Organ failure – death!

10. Body weight loss (%)
ExerciseCapacity
0 21 3 4 5
60%
80%
100%
In cool laboratory conditions, VO2 max has been shown to
decrease with fluid losses, (as little as 2% loss body mass)
In the heat, sweat rates increase even more, such that
fluid intake must be even more closely monitored.

11. 1
2
3
4
5
6
7
8
Urine Color Chart
Assess Hydration
1, 2, or 3: Well
Hydrated
4 or Darker:
Dehydrated
How do athlete’s monitor hydration & rehydration?

12. How much should athletes drink during
exercise?
Fluid requirements vary remarkably between athletes
and between exercise situations.
Factors affecting fluid loss;
Genetics - some people innately sweat more than
others.
Body size - larger athletes tend to sweat more than
smaller athletes.
Fitness - fitter people sweat earlier in exercise and in
larger volumes.
Environment - sweat losses are higher in hot, humid
conditions.

14. How can I tell how much I’m sweating?
Pre exercise weight 70 kg
Post-exercise weight 68.5 kg
Volume of fluid consumed during
exercise 1l (kg)
Exercise duration 2 h
Calculations
• Fluid deficit (l) = 70 kg - 68.5kg = 1.5 kg
• Total sweat loss (l) = 1.5 kg + 1 kg = 2.5 kg
• Sweat rate (l/h) = 2.5 kg / 2hr = 1.25 l/h

15. Calculating sweat rates
An 78kg male takes part in a 1.5 hour pre season football
training session and drinks 500ml litre (0.5kg) of water
during the session.
After he weighs himself, he now weighs 74kg.
What was his sweat rate?
Answer =
3 litres per hour!!!
(78-74+0.5=4.5l / 1.5h = 3l)
This is roughly how much fluid you would lose through sweat
on a warm day during a match!!!

16. Dehydration Status
This athlete has lost 4kg of body mass through fluid
loss, he is obviously now dehydrated. He should
normally weigh 78kg, how dehydrated is he?
(answer in % age)
Answer
Roughly 5%!!!
Effect on performance????
Note: - Athlete’s need to train themselves to drink,
especially in hot conditions.

17. Calculating sweat rates
An 55kg female takes part in a 45 min high intensity
intermittent sprint training session and drinks 500ml
litre (0.5kg) of sports drink during the session.
After she weighs himself, he now weighs 53kg.
What was her sweat rate?
Answer =
3.33 litres per hour!!!
(55-53+0.5= 2.5l/0.75h = 3.33l)

18. Dehydration Status
This athlete has lost 2kg of body mass through fluid
loss, she is obviously now dehydrated. She should
normally weigh 55kg, how dehydrated is he?
(answer in % age)
Answer
Roughly 3.5%!!!
Effect on performance????
+10% affect on her training???

19. Effect on Performance – references!
Armstrong (1985)
Dehydration by as little as 2% can decrease
performance in 5 and 10km races by 6-7%.
Nielsen (1981)
Dehydration by 2.5% decrease capacity to perform
high intensity exercise performance by 45%.
Saltin and Costill (1988)
Dehydration by 5% decreases work capacity by 30%.
Maughan (2000)
3% dehydration will reduce overall (most aspects of)
performance by 10%

20. Body weight loss (%)
ExerciseCapacity
0 21 3 4 5
60%
80%
100%
In cool laboratory conditions, VO2 max has been shown to
decrease with fluid losses, (as little as 2% loss body mass)
In the heat, sweat rates increase even more, such that
fluid intake must be even more closely monitored.

21. Dehydration
“The volume of fluid that most athletes ‘choose’ to drink
voluntarily during exercise replaces less than one-half of their
body fluid losses!”
(Noakes et al., Exercise Sports Science Review, 1993)
It is just as important for athletes to train their stomach’s to drink as it is
for them to train their muscles!

22. Physiological effects of dehydration
Impaired thermoregulation (temperature control)
Decreased sweat rates
Decreased blood flow to skin
Greater increase in core temp. during exercise
Reduced tolerance to heat strain
Decreased stroke volume
Increase heart rate
All these factors dramatically affect performance!

23. Sports Drinks vs Water?
Why are sports drinks a more effective way of
rehydrating athletes than just drinking water?
1. Re-hydrate quicker and more effectively than water,
(absorption rates)
2. Provide extra energy
3. Prolong the effects of fatigue
4. Replaces sweat losses
Can be expensive (make your own)

24. Sports Drinks vs Water?
Most sports drinks aim to provide three nutrients;
what are they?
1. Carbohydrate – to replace energy
2. Water – to replace fluid lost in sweat
3. Electrolytes – which are??????
Minerals lost in sweat e.g. Sodium, potassium,
magnesium, calcium etc.

25. Sport Drinks Ingredients
Carbohydrate
Glucose, fructose, maltodextrins
Enhance performance, fluid absorption and palatability
Electrolytes
Sodium, potassium, chloride, calcium, magnesium
Enhance water absorption, palatability
Maintains thirst
Prevents hyponatraemia (water intoxication)
Caffeine?
Can enhance endurance performance
Can improve alertness
Potential negative effects though, not for everyone!

26. Sport Drinks
Sports Drinks can be Isotonic, Hypotonic or Hypertonic
What does this mean?
Water = 0% CHO
Isotonic = 4-8% CHO Similar to body fluid
Hypotonic = <4% CHO Less than
Hypertonic = >8% CHO More than

27. Sport Drinks
Hypertonic –
slow rate of absorption, usually consumed with other fluids,
best used in recovery stages.
Isotonic –
usually contain sodium to speed up absorption. Can be used
before exercise.
Hypotonic –
These can be more effective than water as they can encourage
fluid replacement through enhanced taste.

28. Fluid Intake
Pre-event
Athlete should be fully hydrated, at least 300-
500ml 10-15 minutes before exercise is
recommended.
Inter-event
150-200ml every 15-20 minutes.
Post-event
150% of sweat rate.

29. Fluid Intake
Re-hydration Strategies
Sweat Losses
Intermittent Exercise
Football/Rugby match = 1-4 litres!
How much should an athlete drink?
Note: this is only a guide many factors can/will affect this!
Before During After
300-500ml
10-15 minutes
before start of
activity
150-200ml
every 15-20 minutes
150% of sweat rate
(up to 6 hrs post
exercise)

30. Sports Drink Recipe 1.
100ml fruit squash (non sugar free)
400ml water
1 small pinch of salt
Mix thoroughly and chill

31. Sports Drink Recipe 2.
250ml fruit juice (no added sugar) orange, apple etc.
250ml water
1 small pinch of salt
Mix thoroughly and chill

32. Sports Drink Recipe 3.
More precise if you want exact CHO concentration e.g.
6%
800ml warm water
200ml sugar free squash (taste)
60g of glucose power
1 pinch of salt
Mix thoroughly and chill

33. Factors to consider when using Sports
Drinks
Palatability
Athlete preference?
Solid Food (i.e. banana) + water
Hydrate before exercise
What is available?
Sports Drinks
At least 1% CHO
20-30mg/l of sodium
5-10mg/l of potassium

34. Remember
The greater the F.I.T.T of exercise, the more
important fluid replacement strategies
become.....
Food
Water
Sports drinks

35. Activities (P5, P7, M4, D2)
1. Devise a simple five point plan to ensure that sports people maintain
an adequate state of hydration, (tips to stay hydrated).
(this plan can be used later on in the unit when formulating diet
plans).
2. Research and find at least 8-10 different sports drinks that are
commonly used by athletes and list their ingredients in terms of
carbohydrate and electrolytes
State whether they are hypotonic, hypertonic or isotonic.
For each drink then state what stage of training/competition they
would by useful for, (pre, during, post-exercise).
Extension
Find out what effect taking the supplement glycerol has on hydration.