Download nutrition for performance hockey

SPORT SCIENCE & MEDICINE TEAM
NUTRITIONAL SUPPORT
NUTRITION FOR PERFORMANCE HOCKEY
This chapter on nutritional issues covers the following:
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Overview
What’s a balanced diet?
Carbohydrate
Protein
Fat
What to eat before a match
What to eat after training/competition
Fluids and hydration
BOA statement on Creatine
BOA statement on use of supplements
OVERVIEW
All great athletes plan their diet as diligently as they plan their training regimen. Neglecting to fuel the
body correctly and provide all of the essential nutrients it needs may contribute to a sub optimal
performance in training and competition. As an elite athlete it is important that you have a good
understanding of the types of foods and fluids you should be taking on board to enable you to
perform at your best.
What fuel?
Hockey is a sport that consists of a variety of exercise intensities ranging from sprinting to standing
still. Fuel for the bursts of intense activity is provided predominantly by carbohydrate and fat is used
during the less intense parts of the game.
Research shows that muscle glycogen is the most important fuel in team sports.
One of the major causes of fatigue during Hockey is depletion of muscle glycogen. Studies have shown
that the use of glycogen is more pronounced in the first than the second half of the game.
Furthermore it is found that players with initially low glycogen stores cover a shorter distance and
sprint significantly less, particularly in the second half than those players with normal muscle glycogen
levels prior to the match.
If blood glucose levels drop during the game this may also lead to a loss of concentration and tactical
skills, and a deterioration of team interactions.
So carbohydrate clearly plays an important part in the diet of an elite Hockey player, but it is also
essential to remember that the body needs a total of approximately 40 nutrients for good health so
the balance of the diet as a whole must be carefully considered.
What’s a balanced diet?
A balanced diet will provide you with enough energy and nutrients to stay healthy, feel good and
perform well in training and competition. Athletes have different requirements to the general
population but essentially the diet should still be made up of the five basic food groups with greater
proportions from some groups due to increased requirements of specific nutrients e.g. carbohydrate
and protein
The main nutrients provided by the diet are carbohydrate, protein, fat, vitamins and minerals.
A good training diet should contain approximately:
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60-70% energy from carbohydrate
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12-15% energy from protein
<30% energy from fat
The daily diet should be made up of a selection of foods from each of the five food groups pictured
below to ensure you consume the correct balance of nutrients required for the body to function.
A brief guide to the five food groups
Bread, other cereals and potatoes
 This group includes bread, potatoes, pasta and noodles, rice and breakfast cereals. It
also includes other cereal grains such as oats, maize, millet and cornmeal and other
starchy vegetables such as yam and plantain.
 Beans and pulses can also be counted as part of this group
 Main nutrients provided by this group include carbohydrate, fibre, some calcium and
iron plus B vitamins
 To increase fibre intake it is useful to eat wholemeal, wholegrain or high fibre
versions of these foods where possible
Fruit and vegetables
 These include fresh, frozen and canned. Dried fruits and fruit juice are also included
 Main nutrients provided include the antioxidant vitamins, C, E and carotene, as well
as folate, fibre and some carbohydrate.
 Fruits and vegetables also contain other compounds called phytochemicals such as
flavonoids (widely distributed in fruits and vegetables), phytoestrogens (Soya is a
good source) and glucosinolates (found in broccoli, cabbage, cauliflower, Brussels
sprouts, kale and mustard). These compounds may help protect us against common
diseases.
 Five portions or more of fruit/vegetables should be eaten per day
 Beans, pulses and juices can be counted as part of this group
Milk and dairy foods
 This group includes milk, cheese, yoghurt and fromage frais, but not butter, eggs and
cream
 Main nutrients provided include calcium, protein, vitamin B12 and vitamins A and D.
Vitamins A and D are not present in very low fat varieties.
 2-3 portions of these foods should be eaten daily
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Lower fat versions should be chosen where possible e.g. skimmed or semi skimmed
milk and lower fat yoghurts and cheeses
Meat, fish and alternatives
 This group includes meat, poultry, fish, eggs, nuts, beans and pulses
 Main nutrients provided includes iron, protein, zinc, magnesium and the B vitamins
especially B12
 Include 2-3 portions of this food group per day.
 Lean meats should be chosen and skin removed from chicken to decrease fat intake
 Pulses and beans are good alternatives to meat and are naturally lower in fat and
also contain carbohydrate and fibre
 Oily fish is a good source of omega 3 fatty acids which can help protect against
heart disease and optimise mental functioning
 Aim for a minimum of 2 portions of fish per week of which at least one should be
oily fish. Oily fish include salmon, trout, mackerel, sardines, pilchards, swordfish,
herring, kipper, eel, and whitebait. These fish count as oily whether they are canned
fresh or frozen. Only fresh tuna counts as an oily fish, as canned tuna has less omega
3 oils, but is still a good protein source. Men can have up to 4 portions oily fish per
week (one portion is 140g), women 2 portions per week. Women who aren’t
planning to be pregnant in the future can also have up to 4 portions per week.
Foods containing fat, foods containing sugar
 Foods containing fat include margarine, butter, other spreading fats and low fat
spreads, cooking oils, oil based salad dressings, mayonnaise, cream, chocolate,
crisps, biscuits, pastries, cake, puddings, ice cream, rich sauces and gravies
 Foods containing sugar include soft drinks, sweets, jam and sugar as well as foods
such as cake, puddings, biscuits, pastries and ice cream
 Foods containing fat do contain important nutrients including essential fatty acids
and fat soluble vitamins especially the antioxidant vitamin E and so a small amount is
needed in the diet
 Generally, high fat foods should be limited as they are high in energy and eating large
quantities can lead to excessive gains in body fat
 A high intake of saturated fat can increase cholesterol levels
 Monounsaturated or polyunsaturated fat should be chosen instead where possible.
 Look out for products with less than 3g fat per 100g as these are low fat
 Foods containing a lot of sugar can be useful to top up carbohydrate requirements
but should not be included in large quantities
The food group ‘bread, other cereals and potatoes’ should make up a substantial part of a hockey
players diet because of the greater need for carbohydrate. Fruit and dairy foods are also a useful
source of carbohydrate.
CARBOHYDRATE
Carbohydrate is the most important fuel for the working muscle and is essential for any form of
exercise. It is also an essential energy source for the brain and central nervous system and so plays a
vital role in hockey where precision, quick decision making skills, dexterity and coordination are
required.
Carbohydrate is stored in the body as glycogen in the muscle and liver. These stores are quite small
and so a regular intake of carbohydrate is needed to keep these stores topped up.
Low glycogen stores will result in poor performance and increase the risk of injury.
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Research shows that low carbohydrate diets can result in lower levels of muscle glyogen and higher
rates of perceived exertion, reduced tolerance for training and fatigue. It is therefore essential to pay
attention to the amount of carbohydrate you eat on a regular basis.
Good sources of carbohydrate to include regularly in your diet include:
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Breakfast cereals – All types but try to include some wholegrain varieties such as
porridge, weetabix, shredded wheat, branflakes, muesli, sultana bran etc
Bread – all types wholemeal, granary, white, pitta, muffins, crumpets, bagels,
chapattis
Pasta and noodles
Rice
Cous cous, polenta, bulgar wheat, millet and other grain products
Potatoes and sweet potatoes
Pizza bases (opt for deep pan thicker bases) the topping can be high in fat so choose
lower fat toppings such as ham and pineapple, vegetarian or ham and tomato. Avoid
too much cheese or salami type toppings
Crispbread, oatcakes, rice cakes, crackers
Beans (baked, red kidney etc), peas and lentils
Root vegetables such as carrots swede, parsnip, swede beetroot
Sweetcorn and popcorn (buttered popcorn has a high fat content)
Fruit (fresh, dried and canned) and fruit juice
Milk and yoghurt
These sources of carbohydrate also provide a variety of other nutrients and so are good choices.
Make sure you have a large portion of carbohydrate with each meal and base snacks on carbohydrate
rich foods.
There are other sources of carbohydrate that can be included in the diet to increase overall intake of
carbohydrate but they are not as rich in other nutrients and some may contain higher amounts of fat.
These include:
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Cereal bars (fat content can be high, so check the label)
Biscuits – rich tea, fig rolls, plain digestives, ginger nuts, and jaffa cakes are lower in fat than
many other biscuits
Cakes – again be aware that many cakes have a high fat content. Lower fat alternatives
include malt loaf, hot cross buns, and fruit loaf.
Jam, marmalade, honey, syrup and treacle
Sweetened soft drinks
Sport drinks
Sugar confectionary e.g. jelly baby’s, wine gums etc
Carbohydrate - How much is enough?
The amount of carbohydrate you need to eat each day depends on the amount of training you do on
a daily basis. The following table is a guide to the amount you should be eating.
On average, Hockey players would require 5-8g carbohydrate per kg body weight.
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Daily recovery / fuel needs for moderate duration (< I
hour per day) / low intensity training
Daily recovery / fuel needs for moderate to heavy
endurance training (1-3 hours per day)
Daily recovery/fuel needs if undertaking an extreme
exercise program (i.e. 4-6 + hours per day)
5-7g carbohydrate per kg body weight per day
7-12g carbohydrate per kg body weight per
day
10-12g carbohydrate per kg body weight per
day
(Ref: J sports sciences vol. 22, No. 1, Jan 2004)
To give you an idea of the carbohydrate content of different foods, the items below show the portion
sizes of foods that will provide 50g carbohydrate.
Bakery Products
2 slices bread from large thick cut loaf
3 slices bread from large medium sliced loaf
1 large bap
2 rolls
1 bagel
1 large pitta bread
2 crumpets/English muffins
2 currant buns/hot cross buns
2-3 slices malt loaf
3 scotch pancakes
4 pikelets
Breakfast Cereals
1 large bowl breakfast cereal
3 weetabix or shredded wheat
11/2 bowls porridge made with milk
Grains And Cereals
8 tablespoons cooked pasta
4 tablespoons cooked rice
1 large tin spaghetti in tomato sauce
Potatoes
1 medium jacket potato with skin
5 scoops mashed potato
5 small egg sized potatoes
Fruit
2 large bananas
4 apples
2 large mangoes
large bunch grapes
1 pint fruit juice
2 tablespoons raisins/sultanas
14 dried apricots
5 dried figs
400ml fruit smoothie
Dairy Foods
2 cartons yoghurt
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2 pints milk
500ml milkshake
Cereal Bars
2 Jordans frusli bars
1 ½ Nutrigrain elevenses
2 Kellogg’s nutrigrain bars
2 Geobars
2 Alpen bars
Biscuits
4-5 Fig rolls
6 jaffa cakes
6 gingernuts
5 digestives
Drinks
80ml Ribena diluted with 500ml water
PROTEIN
Protein is an important nutrient required for the growth and maintenance of body tissues including
muscle and the production of hormones and enzymes. It can also be used as an energy source when
carbohydrate is in short supply.
Strength and endurance training increase the requirements for protein. Requirements increase when
participating in endurance training because of the adaptive changes that occur during this kind of
exercise and because it can be used as an energy source when carbohydrate is depleted.
During strength training additional protein is required for muscle growth and development.
Many carbohydrate foods also provide small amounts of protein and so as you increase your
carbohydrate intake you will automatically obtain extra protein from these foods. It is therefore
unnecessary to eat extra large portions of traditional protein rich foods or to take a protein
supplement. All that is necessary is to ensure you eat moderate portions of a protein rich food at 2-3
meals each day such as chicken, meat, fish, beans, lentils etc. Also remember to include a protein
source in post training snacks, particularly when doing strength training.
Animal protein sources include meat, chicken, fish, milk, cheese, and yoghurt.
Vegetables protein sources include pulses (beans, peas, and lentils), tofu, quorn, and textured
vegetable protein, nuts and seeds
Animal sources of protein can be high in fat and so it is important to remove fat from meat, skin from
chicken and choose low fat dairy foods.
How much protein do you need?
Hockey is a power sport and requires both strength and endurance. As a consequence your protein
requirements are 1.4 -1.7g protein per kg body weight. If performing more strength training in your
program aim for the upper end of the range i.e. 1.7g protein/kg.
To give you an idea of the protein content of different foods, the tables below show the portion sizes
of foods that will provide 20g protein (animal sources) and 10g protein (vegetable sources)
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Food portions containing approximately 20g animal protein
Protein source
Beef, lamb, pork
Turkey, chicken
Liver
Fish
Fish fingers
Canned salmon/tuna
Prawns
Cockles
Eggs
Cheddar cheese
Edam cheese
Brie
Cottage cheese
Milk – skimmed/semi skimmed
Yoghurt- low fat
Approximate weight
75g
75g
100g
100g
135g
100g
100g
170g
75g
75g
100g
150g
600ml
450ml
Handy measure
2 medium slices
1small breast
2 slices
1 small fillet
5 fingers
1 small can
Approx. 30 prawns
Approx. 40 cockles
3 medium
2 matchbox sizes
2 matchbox sizes
4 tablespoons
1 pint
3 cartons
Food portions containing approximately 10g vegetable protein
Protein source
Nuts (e.g. peanuts, cashews etc)
Seeds (e.g. sunflower, sesame)
Baked beans
Kidney beans/split peas
Lentils
Quorn
Tofu, steamed
Soya milk
Hummus
Peanut butter
Bread
Pasta/noodles
Rice
Bran flakes
Approximate weight
50g
50g
200g
150g
150g
100g
125g
350ml
125g
50g
125g
250g
450g
100g
Handy measure
1 medium packet
4 tablespoons
5 tablespoons
4 tablespoons
4 tablespoons
½ packet
Approx ½ pint
4 tablespoons
Thickly spread on 2 slices bread
3 medium slices
8 tablespoons
11 tablespoons
11/2 large bowls
FAT
Fats provide a highly concentrated form of energy as well as fat soluble vitamins, antioxidants and
essential fatty acids.
Fat is essential for the production of hormones and prostaglandins, is a structural component of brain
tissue and creates a protective blanket around essential organs.
Unlike glycogen, which can only be stored in limited amounts, there is always sufficient fat available as
fuel for exercise. Fat should provide no more than 30% of the energy intake
There are 3 main types of fat in the diet:
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Saturated: found in animal products (butter, cheese, fat on meat) coconut oil, palm oil,
hydrogenated fats, cakes, biscuits, pastry. A diet high in saturated fat can lead to an increase
in cholesterol levels, a risk factor for heart disease.
Monounsaturated: found in olive oil, rapeseed oil, almonds, peanuts, hazelnuts, pecans and
avocado. Monounsaturated fats do not increase cholesterol levels when substituted for
saturates.
Polyunsaturated: found in fish oil, sunflower, corn and safflower oils, linseed and soybean.
Polyunsaturated fats whilst not increasing cholesterol, do decrease the HDL component and
so are less beneficial to health than monounsaturates.
Essential fatty acids
Polyunsaturated fats provide the essential fatty acids, linoleic acid (omega 6) and alpha linolenic
(omega 3), which cannot be produced by the body.
Omega 6 fatty acids regulate the actions of many cells.
Omega 3 fatty acids are essential for brain and retina (eye) function and can help reduce the risk of
heart disease.
Good sources of omega 3 fatty acids include oily fish (sardines, mackerel, salmon, tuna, trout,
swordfish, pilchards, whitebait), linseeds, rapeseed oil, soya and Omega 3 enriched eggs.
Fat intake, particularly saturated fat should be reduced overall whilst maintaining an adequate intake of
the essential fatty acids. Excess fat in the diet is stored very efficiently as body fat and so if fat loss is
an aim, fat intake should be significantly reduced.
To reduce fat intake:
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Use a reduced fat spread instead of butter or margarine. Choose monounsaturated or
polyunsaturated based spreads
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Remove visible fat from meat and skin from poultry.
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Use skimmed/semi-skimmed milk and low fat yoghurts/fromage frais instead of full fat
versions.
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Choose reduced fat cheeses or choose medium fat cheeses such as edam, gouda,
camembert, brie, goats cheese, mozzarella, feta and ricotta. Cottage cheese is very low fat
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Use minimal amounts of fat for cooking – choose olive or rapeseed oil.
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Avoid fried foods and avoid adding fats to cooked foods e.g. butter on vegetables etc.
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Have potatoes as jacket, boiled or mashed more often than chips. If you do have chips go for
thick cut oven chips (contain 7.6g fat per medium portion compared to 35g for fine cut chips
fried in sunflower oil)
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Keep hidden sources of fat to a minimum including foods such as pastry, pies, biscuits, cakes,
crisps, chocolate and meat products.
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Look at food labels and compare to the guide below:
Reference guide to food labels
Total fat
Saturated fat
Fibre
Sodium
‘A lot’ is
More than 20g
More than 5g
More than 3g
More than 0.5g
‘A little’ is
Less than 3g
Less than 1.0g
Less than 0.5g
Less than 0.1g
Note: salt = 2.5 x sodium value
These figures are compared with the per serving figure for a whole meal or the 100g for a snack.
As an example, a male hockey player requiring 3200kcals per day could eat 90g fat per day, which
would equate to 25% of total energy intake.
A female hockey player requiring 2500kcals per day could eat 70g fat per day, which would also
equate to 25% of total energy intake.
WHAT SHOULD I EAT BEFORE A MATCH?
Pre match meal
This meal should be eaten 1-4 hours before the match. About 2 hours before usually works well. It
should be high in carbohydrate, low in fat, low to moderate in protein but with a low amount of fibre
if nerves send you running to the bathroom.
Too much protein will slow down the movement of foods from the stomach and will make you feel
uncomfortable. It should provide approximately 200-300g carbohydrate.
Suitable foods would be:
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Pasta with tomato based sauce with chicken and vegetables or other low fat sauce
Stir fried noodles or rice with vegetables and lean meat, chicken or prawns
Vegetable and chicken risotto
Cereal and milk/yoghurt
Porridge made with milk
Toast/muffins/crumpets with honey, jam or marmalade
Spaghetti in tomato sauce or baked beans (if not too high in fibre) on toast
Sandwiches with lean meat, tuna or salmon
Jacket potatoes with low fat toppings such as baked beans, cottage cheese or low fat soft
cheese, tuna and sweetcorn
Bagels, Baguettes or sandwiches with lean cold meat, tuna or salmon
Low fat milk shakes or smoothies
Cereal bars/breakfast bars
Mullerice and Muller light yoghurt
Bananas
Isotonic sports drinks
Pre match snack
You may find it beneficial to take a small carbohydrate snack 30-60minutes before the match to top
up blood glucose levels. This could include:
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Fresh or dried fruit
Cereal bars
Fig rolls
Rice cakes
Fruit loaf / malt loaf
Scotch pancakes
Sports drinks
Low fat yoghurt / mullerice type product
What should I eat after training?
Effective recovery from training is crucial to prevent that mid week slump in energy levels. Rapid
replenishment of the glycogen stores used during training and competition is essential. This is
particularly important if you are training every day or more than once per day.
When you finish training, you should aim to have a carbohydrate rich food or drink within 30 minutes
as the muscle can store carbohydrate as glycogen more efficiently during this time.
You should aim for 1 - 1.2g carbohydrate per kg body weight, so usually this would be a minimum of
50g carbohydrate. This amount should be consumed with 30 minutes and then repeated after 2 hours
until normal meal patterns are resumed.
This process is a must if you have less than 8 hours between training sessions or events, but not so
crucial if you have 1 or more days between intensive training sessions. However it is important you
consume a meal or snack soon after the end of training
It would also be beneficial if the recovery snack / drink contained some protein to facilitate the repair,
growth and development of muscle tissue. Ideally the snack should provide approximately10-20g
protein and 50-100g carbohydrate depending on body weight.
If recovery time before the next session is short, the type of carbohydrate consumed should ideally
be one that is quickly absorbed into the bloodstream i.e. a high glycaemic index food
The following are examples of recovery snacks all providing 50g carbohydrate. They can be combined
with each other for variety and to increase the amount of carbohydrate provided. For example 500ml
fruit juice and one English muffin and jam provides 75g carbohydrate. Milk or yoghurt based drinks are
an excellent way of consuming protein after training.
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650 – 800ml isotonic sports drink
500ml low fat milk shake e.g. Yazoo, gulp, Friji, Duns River Nourishment light, For goodness
shakes
500ml fruit juice
300ml carbohydrate/energy drink e.g. lucozade energy/500ml SIS PSP22 (50g powder mixed
with 500ml water)
500ml fruit smoothie
2 large bananas
3 medium pieces fruit
2 nutrigrain bars/twists
2 rice krispie squares
2 frusli bars
2 crumpets/English muffins with jam
3 scotch pancakes
2 teacakes
2 hot cross buns
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1 bagel
2-3 slices malt loaf
2 fruit scones
Large bowl of breakfast cereal with skimmed milk
2 tablespoons raisins/sultanas (70g)
5 dried dates/100g dried apricots (approx 14) or figs (approx.5)
Recovery snacks/drinks providing approx 50g carbohydrate and 10-20g protein include:
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500ml Friji milkshake (51g carbohydrate, 17g protein, 4.0g fat, 310kcals)
500ml breaktime milkshake (45.5g carbohydrate, 16.5g protein, 0.5g fat, 255kcals)
500ml For Goodness Shakes milkshake (46g carbohydrate, 16.4g protein, 1.5g fat, 248kcals –
banana flavour)
500ml Gulp (49g carbohydrate, 19g protein, 5g fat, 315kcals – strawberry)
500ml semi skimmed milk plus one cereal bar e.g. frusli (46.3g carbohydrate, 18.5g protein,
4.8g fat, 297kcals)
420g can nourishment light (48g carbohydrate, 23g protein, 3.8g fat, 319 kcals)
Homemade fruit smoothie with 150g yoghurt, ½ pint fruit juice, I banana plus 3 tablespoons
skimmed milk powder (approx 65g carbohydrate, 20g protein, 300kcals, 2g fat)
I round sandwiches (thick sliced bread) with low fat spread and tuna/ chicken/ meat/cottage
cheese plus one piece fruit (approx: 400kcal, 64g carbohydrate, 22g protein, 9g fat)
200g low fat yoghurt plus cereal bar and banana (61.5g carbohydrate,12g protein, 4.8g fat,
331kcals)
Add in cereal bars, sports drinks, bananas, dried fruits etc to add more carbohydrate to match your
needs
FLUID AND HYDRATION
Fluids play a vital role in maintaining body functions and makes up 66% of body weight. It is required
for the transport of vital nutrients around the body, removal of waste products, digestion and
absorption of food and the maintenance of body temperature.
During any type of physical activity, heat is produced and lost from the body by the evaporation of
sweat. This fluid loss is linked to the need to maintain the body temperature within narrow limits.
Dehydration can have serious negative effects on performance and so it is important to keep hydrated
at all time by frequent drinking before, during and after exercise.
The effects of dehydration
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Exercise performance can be impaired by 10-20% if dehydrated by as little as 2% of body
weight
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Fluid losses in excess of 3% increases the risk of heat cramps, heat exhaustion or heat stroke
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Dehydration can affect mental function, slowing reaction-response times and decision making
skills, which are vital in team sports.
Fluid loss depends on sweat rates and can vary between 500-2000ml per hour depending on
environmental temperature. Fluid should be replaced during exercise preferably at a rate equal to
sweat rate. It is important not to over consume fluids as this may potentially cause the problem of
hyponatremia.
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Sweat rate
All athletes should know their sweat rate and aim to consume sufficient fluid during each training
session/game to match fluid losses.
To calculate sweat rate:
o
Record pre training weight (kg) in minimum clothing
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Record post training weight (kg) removing sweaty clothing first
o
Subtract post training weight from pre training weight to obtain weight lost – convert kg to
g’s i.e. multiply by 1000. For example if weight loss is 1.2kg this would be 1200g
o
Record the amount of fluid (ml) consumed during training i.e. weigh drinks bottles before
and after training, noting any refills
o
Record volume of any urine (ml) passed during that time (this volume will only be subtracted
if urine was passed prior to post exercise body weight)
o
Record the length of time spent training in hours
SWEAT RATE = (Pre exercise body weight – post exercise body weight) + fluid intake –
urine volume, Exercise time in hours
o
1 kg weight loss equates to 1 litre fluid loss
o
For every kg of weight lost, 1.25 -1.5litres fluid is needed to replace it due to the continuing
loss of sweat after exercise finishes and the urine losses that persist even in the dehydrated
state. This will ensure optimal hydration is achieved after the event.
Sample sweat rate calculation
A
Name
Athlete A
B
Date
12-Mar
C
Body Weight before exercise
61.7Kg
D
Body weight after exercise
60.3Kg
E
Change in BW (C-D)
1.4kg 1400g (Kg x1000)
F
Drink volume
420ml
G
Urine volume
90ml
H
Sweat loss
1730ml (E+F-G)
I
Exercise time
90min (1.5hrs)
J
Sweat rate (H/L)
19ml/min, 1153ml/hr
Athlete A should therefore consume just over 1 litre per hour to keep up with sweat rate and
maintain a good hydration status
During exercise, fluids should be replaced at a rate equal to sweat rate, which will vary depending on
exercise intensity, temperature, humidity, hydration status, acclimatisation and the type of clothing
worn.
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Athletes should aim to start training in a fully hydrated state. During the day, hydration
should be maintained by drinking water, fruit juices, squashes etc. Excessive amounts of tea
and coffee should be avoided
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500 - 600ml water or sports drink (to maximise glycogen stores) should be consumed 2 –3
hours before exercise and then 200-300ml 10-20 minutes before exercise. Sports drinks are
useful before exercise if carbohydrate intake during the day has not been optimal or if there
has been a long gap between the last meal/snack and the training session or if the session will
be high intensity.
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During training, 200-300ml fluids should be consumed every 10-20 minutes. These are
general guidelines but individual requirements should be calculated to avoid under or over
hydration
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After training the fluid required to replaces losses should ideally be consumed within 2 hours
to ensure that optimal hydration is achieved as soon as possible in case a further event is
imminent.
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The post exercise rehydration drink should contain carbohydrate to help replace glycogen
stores and sodium to help conserve water and encourage the drive to drink (i.e. an isotonic
or hypertonic sports drink)
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Keeping the volume of fluid in the stomach at 600ml or more facilitates faster emptying and
absorption from the stomach and into the blood stream so hydration can keep pace with
sweat loss
TYPES OF FLUID
It is important that athletes take fluid on board for any exercise lasting over 30 minutes.
Water may be sufficient for low intensity exercise up to 45-50 minutes. For higher intensity exercise
of 45-50mins where fluid losses are greater a sports drink would be of benefit.
An intake of 1g carbohydrate per minute maintains optimal carbohydrate metabolism – for example 1
litre of a 6% carbohydrate drink per hour of exercise. Generally athletes should choose an isotonic
(5-8% carbohydrate) sports drink unless training in very hot climates where large quantities of fluid
are required in which case a hypotonic (1-3% carbohydrate) sports drink may be more appropriate.
30-60g carbohydrate per hour in the form of a sports drink will maintain energy levels and enhance
performance. Preventing low blood glucose levels by consuming a sports drink can also be beneficial
to immune system function.
Cold fluids encourage greater consumption so a temperature of 10-15 degrees centigrade is
recommended for fluids.
SPORTS DRINKS
Sports drinks are fluids containing carbohydrate and electrolytes. The carbohydrate is usually a
mixture of glucose, sucrose, fructose and maltrodextrins (glucose polymers which are glucose units
linked together). High concentrations of fructose (>10%) can cause gastric upset and decrease water
absorption. The amount of fructose in a drink should be no more than 2-3g/100ml (2-3%).
The electrolytes added are sodium and sometime potassium and magnesium. Glucose absorption
requires the presence of sodium and is an active process, so the addition of sodium stimulates glucose
and water absorption. The provision of 22-30mmol (506 - 690mg) sodium per litre fluid would be
SPORT SCIENCE & MEDICINE TEAM
appropriate to replace most of the sodium lost from sweating whilst at the same time remaining
palatable. Sweat contains 40-80mmol sodium/l.
Drinks containing 5-8% glucose or sucrose are absorbed into the body more rapidly than water and
also provide some energy. A slightly higher concentration of carbohydrate can be used if the
carbohydrate source is a glucose polymer or maltodextrin, without decreasing the rate of stomach
emptying.
OSMOLALITY OF SPORTS DRINKS
An isotonic drink has the same number of dissolved particles as are found in plasma (about
290mosmol per kg). The dissolved particles are electrolytes and carbohydrates such as glucose or
glucose polymers. Isotonic drinks promote water and carbohydrate absorption.
A less concentrated drink containing 1-3% carbohydrate (hypotonic) has a lower osmolality and
promotes water absorption but provides less carbohydrate energy.
Drinks with a higher osmolality, usually >10% carbohydrate energy, are hypertonic and slow gastric
emptying thus decreasing fluid absorption. These more concentrated drinks are useful as recovery
drinks after exercise. They can also be used in situations when provision of fuel takes priority over
fluid replacement.
EXAMPLES OF COMMONLY AVAILABLE ISOTONIC SPORTS DRINKS
Drink
Carbohydrate
(g) per 100ml
6
5.7
Energy
(kcal) per
100ml
25
22.8
Sodium
(mmol/mg)
per 100ml
1.8mmol/41mg
1.3mmol/30mg
Gatorade
SIS Go electrolyte
(powder)
Lucozade sport
Powerade
6.4
6
28
24
2.2mmol/50mg
2.2mmol/50mg
MONITORING
It is important that you learn to monitor your own hydration status. You should be aware of the
symptoms of dehydration, of how to use urine volume and colour as an indicator of hydration status
and the importance of pre and post body weight measurements
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Signs and symptoms of dehydration include thirst, irritability, and general discomfort,
followed by headache, weakness, dizziness, cramps, chills, vomiting, nausea, head or neck
heat sensations and decreased performance
Thirst is a poor indicator of the need to drink to drink. Thirst indicates that 1.5-2.0l fluid
have already been lost
The ‘pee’ test. When fully hydrated large amounts of very pale yellow urine will be passed.
Numbers 1-3 should be the aim. Dark yellow urine is an indication of dehydration although
vitamin supplements containing riboflavin will colour the urine dark yellow. Please refer to
credit card sizes ‘pee chart’ to see the colours 1 to 8. As discussed pre and post training
weight can be used to calculate fluid losses. As a minimum, aim for a body weight change of
less than 2%.
Other tests that can be done in the field include urine specific gravity
SPORT SCIENCE & MEDICINE TEAM
Urine specific gravity measurement
This is done using a refractometer and should be done using mid stream urine. This can be performed
by the physiologist or dietitian and gives a figure, which correlates to hydration status. See chart
below.
Indexes of hydration status
Condition
Well hydrated
Minimal dehydration
Significant
dehydration
Serious dehydration
% Body weight
change
+1 to –1
-1 to –3
-3 –5
Urine colour
1 or 2
3 or 4
5 or 6
Urine specific
gravity
<1.010
1.010 – 1.020
1.021 – 1.030
>5
>6
>1.030
(Pre exercise body weight – post exercise body weight) x 100
Pre exercise body weight
HYPONATREMIA
A condition called hyponatremia can occur in athletes who consume excessive amounts of fluid or
who drink low sodium fluids. It is defined by low blood sodium levels less than 130mmol/l.
Hyponatremia occurs most frequently in sports lasting longer than 4 hours, during lower intensity
endurance activities, when athletes drink large volumes of water without adequate sodium intake.
Signs of hyponatremia are similar to those of heat stroke such as nausea, vomiting, extreme fatigue,
respiratory distress, and central nervous system disturbances (i.e. dizziness, confusion, disorientation,
coma and seizures). It also has unique characteristics such as low plasma sodium levels. Other
symptoms may include worsening headache, normal exercise core temperature (generally not >
104ºF), swelling of the hands and feet. If hyponatremia occurs medical help should be sought.
Prevention of hyponatraemia
You should be aware of the fluid replacement guidelines and should not replace fluids in excess of
sweat losses. You should use a sports drinks containing sodium, monitor body weight and aim not to
gain weight during a training session. Consuming a little extra sodium during meals and snacks during
continuous days of training in a hot climate will also help maintain blood sodium levels.
FLUID INTAKE IN THE HEAT
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The immediate effect of exposure to heat is an increase in sweat rate. Heat acclimation
induces physiologic changes that may alter individual fluid replacement considerations. Sweat
rate will be greater than normal after 10-14 days of heat exposure, so fluid intake should be
increased accordingly using pre and post weights to calculate sweat rate as previously
discussed.
During the first week of training in a hot environment the hydration status should be closely
monitored, as the sweat rate will increase for any given bout of training thus requiring a
greater fluid intake.
General guidance for fluid replacement in the heat during training is 750-1250ml of sports
drink per hour but this should be adjusted for individuals
Increase sodium intake during the first 3-5 days of heat exposure as there is an increase in
the amount of sodium lost in sweat
After 5-10days the sodium concentration of sweat decreases and normal sodium intake is
sufficient
SPORT SCIENCE & MEDICINE TEAM
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If homemade sports drinks are used rather than commercial varieties then salt should be
added to these (1/4tspn -1.25g per litre) to ensure salt losses are replaced. This would
equate to 500mg sodium (sodium x 2.5 = salt)
To prevent taking on board excess carbohydrate, hypotonic (1-3%) sports drinks may be
more appropriate during exercise in the heat
Keeping fluids chilled will encourage a greater intake
Be aware of signs of dehydration and heat illness such headaches, nausea, vomiting,
weakness, dizziness. Confusion/disorientation and irrational behaviour can occur with heat
stroke
Compiled by Wendy Martinson, Accredited Sports Dietician. August 2005. Wendy has
also written documents on the following:
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Creatine
Caffeine
Fluid guidelines
Supplement guidelines
BOA STEERING GROUPS' POSITION STATEMENT ON CREATINE
Supplementation with creatine may result in improved performance in short duration high intensity
exercise. The biggest effects may be seen in training consisting with repeated high intensity efforts
with short recoveries which may over time lead to performance enhancement. Not all athletes will
benefit and any responses are variable although the greatest benefit may be experienced by
vegetarians. Those who eat no meat or fish tend to have low muscle creatine content. A loading dose
of 20 gms per day for three to five days has been shown to increase the creatine content of muscle
but 3 gms per day over 30 days will have the same effect and 2 gms per day will maintain levels. There
is no increase with higher doses.
It is not known how long creatine can safely be taken for. There is no evidence at present of long or
short term detrimental effects, but there are several potential side effects. Weight gain is common
and this may be of major significance in weight category sports. Other short term side effects are
unclear and the long term effects of taking creatine are not known, in particular the effect of creatine
supplementation on athletes under 18 years has never been studied thus athletes from junior squads
should not take creatine.
Any supplement including creatine is taken at an athlete's own risk and responsibility.
To help you to make a fully informed decision on whether or not it is an appropriate supplement for
you to take, you should talk to your team physician or sports dietitian / nutritionist.
BOA STEERING GROUP’S ADVICE TO UK ATHLETES ON THE USE OF
SUPPLEMENTS
UK Athletes are strongly advised to be extremely cautious about the use of any supplements.
We cannot guarantee that any particular supplement, including vitamins and minerals, ergogenic aids
(such as creatine), and herbal remedies, is free from prohibited substances and therefore supplements
are taken at an athlete's risk and personal responsibility. Always consult a qualified sports nutritionist,
dietician or sports doctor before taking supplements, and if a vitamin or mineral supplement is
recommended, pharmaceutical-grade products may reduce the risk of using a contaminated or poorly
labeled product.
SPORT SCIENCE & MEDICINE TEAM
What is a medicine? What is a supplement?
Athletes should be aware that any product that claims to restore, correct or modify the body's
physiological functions should according to current legislation, be licensed as a medicine. Licensed
medicines can be identified by looking for a product license number, which will look like this:
PL0242/0028 (numbers will change with each product). Supplements will not contain a product license
(PL) number as they are not licensed medicines.
Supporting Athletes
UK Sport, HCSCs, the BOA, the BPA and NSMI are committed to supporting UK athletes, and whilst
a solution to this problem with contaminated and poorly labeled supplements may not be possible, we
are working towards achieving this. The statement above is intended to protect the integrity and
reputation of UK Athletes by highlighting the risks involved in using supplementation.
Vitamin and Mineral supplementation
For athletes consuming a normal, varied and balanced diet, that meets their energy requirements,
there is no evidence that vitamin and mineral supplementation is necessary to enhance health or
performance. In fact, excessive ingestion of vitamins and minerals can be dangerous to health.
There are some practical situations in which qualified medical practitioners, accredited sports
dietitians and registered nutritionists, may recommend specific vitamins or minerals for certain
individuals (e.g. if iron stores are low). However, these should be taken with qualified expert advice
and only used as directed or prescribed. Caution is needed because some multi-vitamin, mineral and
nutritional supplements may contain prohibited substances that are not recorded on the label.
Ergogenic Aids
Ergogenic aids include many substances that are banned in sport. Furthermore there are many
ergogenic aids which could result in a positive drugs test. One ergogenic aid that is widely used and is
not on the banned list is creatine monohydrate. Some creatine products have been found to contain
prohibited substances that were not identified on the label. UK Sport and the BOA cannot provide a
guarantee as to the safety of ergogenic aids and therefore advise extreme caution is an athlete
chooses to use them. For more information on creatine, consult the BOA Statement on creatine for
notes on its use and safety.
Herbal Remedies
Herbal remedies have also been found to contain prohibited stimulants or other substances which
may not be listed on the label.
These products are difficult to quality assure and therefore a guarantee cannot be given as to their
safety or legality.