Nutrition and Hydration for Performance

As a sports person 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. If the body is not fuelled correctly it may contribute to a sub-optimal performance.

A balanced diet will provide you with enough energy and nutrients to stay healthy feel good and perform well in training and competition. As a sports person you have different requirements to the general population, but essentially the diet should still be made up of the five basic food groups with an increased requirement of specific nutrients in particular carbohydrate and protein.

The 5 food groups are:

• Bread, other cereals and potatoes
• Milk and dairy foods
• Foods containing fat and / or sugar
• Meat, fish and alternatives
• Fruits and vegetables

The main nutrients provided by the diet are carbohydrate, protein, fat, vitamins and minerals.

A good training diet should contain approximately:

• 60-70% energy from carbohydrate
• 12-15% energy from protein
• <30% energy from fat

 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 sports which require precision, quick decision making skills and coordination.

Carbohydrate is stored in the body as glycogen in the muscle and liver. Stores are quite small however so a regular intake of carbohydrate is needed to keep these stores topped up. Low glycogen stores may lead to a decrease in performance, early fatigue and an increased risk of injury.

Diets low in carbohydrate can result in lower levels of muscle glycogen and higher rates of perceived exertion, reduced tolerance for training and fatigue. To ensure you perform to the best of your ability it is essential to pay attention to the amount of carbohydrate you eat. The amount you will require each day depends on the amount of training you do.

Good sources of carbohydrate to include regularly in your diet include:

•  Breakfast cereals – especially wholegrain varieties
• Bread - wholemeal, granary, pitta, muffins, crumpets, bagels
• Pasta, noodles, rice, potatoes, cous cous
• Rice cakes, crackers, oatcakes
• Fruit (fresh, dried, canned) and fruit juice
• Milk and yoghurt

Protein

Protein is an important nutrient required for the growth and maintenance of body tissues including muscle and the production of hormones and enzymes.

Endurance training increases the requirements for protein due to adaptive changes that occur during this kind of exercise. Also although not readily used as an energy source in the body; if carbohydrate and fat stores are depleted protein may be used as a fuel. Strength training also increases the requirements for protein to assist with muscle growth and development.

It is unnecessary to eat extra portions of traditional protein rich foods or to take a protein supplement because many carbohydrate foods also provide small amounts of protein. Therefore as you increase your carbohydrate intake you will automatically obtain extra protein from these foods. All that is necessary is to ensure you eat moderate portions of protein rich foods (e.g. chicken, meat, fish, beans, lentils) at 2-3 meals each day. Try to include a protein source in post training snacks, particularly when doing strength training, to promote muscle growth and repair

Fat

Fats provide a highly concentrated form of energy as well as fat soluble vitamins, antioxidants and essential fatty acids. 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.

To reduce fat intake to 30%:

• Use a reduced fat spread instead of butter or margarine.
• Remove visible fat from meat and skin from poultry.
• Use skimmed / semi-skimmed milk and low fat yoghurts instead of full fat versions.
• Choose reduced fat cheeses
• Use minimal amounts of fat for cooking
• Avoid fried foods and avoid adding fats to cooked foods
• Keep hidden sources of fat to a minimum including foods such as pastry, pies, biscuits, cakes, crisps, chocolate and meat products.

When should I eat before exercise?

Food consumed before exercise is only useful once it's been digested and absorbed, so you need to time your food intake so that the fuel becomes available during the exercise period. The time required for digestion depends on the type and quantity of food consumed. Generally, foods higher in fat, protein and fibre tend to take longer to digest than other foods, and may increase the risk of stomach discomfort during exercise. Large quantities of food take longer to digest than smaller quantities. You need to experiment to find the timing that best suits your individual needs. Generally, tolerance is better during lower intensity activities, or sports where the body is supported (e.g. cycling, swimming) compared to sports such as running where the gut moves about during exercise. A general guide would be to have a meal about 3-4 hours before exercise, and a snack 1-2 hours before.

What should I eat?

Food eaten before exercise needs to provide carbohydrate, should be low in fat and provide a moderate amount of fibre.

The following are suitable to eat 3-4 hours before exercise:

• Crumpets with jam or honey + flavoured milk
• Baked beans on toast
• Breakfast cereal with milk
• Fruit salad with fruit-flavoured yoghurt
• Pasta or rice with a sauce based on low-fat ingredients

The following snacks are suitable to eat 1-2 hours before exercise:

• Liquid meal supplement
• Milk shake or fruit smoothie
• Sports bars
• Breakfast cereal with milk
• Fruit
• Cereal bars

The following foods are suitable to eat if there is less than 1 hour before exercise:

• Sports drink
• Carbohydrate gel
• Sports bars
• Jelly beans

After exercise

Effective recovery from exercise is crucial to replenish glycogen stores rapidly. You should aim to have carbohydrate rich food or drink within 30 minutes as the muscle can store carbohydrate more efficiently during this time. It is advisable that the recovery snack contains some protein to facilitate the repair, growth and development of muscle tissue. Ideally the snack should provide approximately 10-20g protein and 50-100g carbohydrate depending on body weight.

The following are examples of recovery snacks all providing 50g carbohydrate:

• 500ml fruit juice
• 500ml fruit smoothie
• 2 large bananas
• 2 nutrigrain bars / twists
• 2 hot cross buns
• 1 bagel
• Large bowl of breakfast cereal with skimmed milk

Recovery snacks / drinks providing approx 50g carbohydrate and 10-20g protein include:

• 500ml milkshake
• 500ml semi skimmed milk plus one cereal bar
• 1 round sandwiches with low fat spread and tuna/ chicken/ meat/ cottage cheese plus one piece of fruit
• 200g low fat yoghurt plus cereal bar and banana

Fluid and Hydration

Fluid plays a vital role in maintaining body functions and makes up 66% of body weight. Fluid 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 exercise, heat is produced and lost from the body by the evaporation of sweat. Dehydration can have serious negative effects on performance and so it is important to keep hydrated at all times by drinking regularly before, during and after exercise.

The effects of dehydration:

• Exercise performance can be impaired by 10-20% if dehydrated by as little as 2% of body weight.
• Dehydration can affect mental function, slowing reaction-response times and decision making skills.
• 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.

Fluid loss depends on sweat rates and can vary between 0.5-2.0l per hour depending on environmental temperature and individual sweat rates. To ensure you consume sufficient fluid during each training session to match fluid losses, you will need to calculate your sweat rate. This can be done by recording your weight pre training in minimum clothing, and then after training removing sweaty clothing first. For every 1kg lost, 1.5l of fluid needs to be consumed along with electrolytes to replace salts lost in sweat.

• You should aim to start exercise in a fully hydrated state.
• 500-600ml of water or a sports drink (to maximise glycogen stores) should be consumed 2-3 hours before exercise and then 200-300ml 10-20 minutes before exercise.
• During training 200-300ml fluids should be consumed every 10-20 minutes.
• During exercise isotonic fluids should be consumed, this means drinks which contain the same amount of electrolytes as the blood, this increases the rate of water absorption compared to drinking water alone. 
• After training the fluid required to replace losses should ideally be consumed within 2 hours to ensure that optimal hydration is achieved as soon as possible.
• The post exercise rehydration drink should contain both carbohydrate and sodium: carbohydrate to help replace glycogen stores and sodium to help conserve water and encourage the drive to drink.
• Keeping the volume of fluid in the stomach at 600ml or more facilitates absorption of fluid from the stomach and into the blood stream, thereby ensuring that hydration can keep pace with sweat loss.
• These are general guidelines so individual requirements should be calculated.

Monitoring

It is important to learn to monitor your own hydration status. Thirst is not a good indicator of dehydration as it indicates that 1.5-2.0 litres fluid has already been lost. Urine volume and colour is a far better indicator of hydration status. You should urinate large volumes frequently and urine should be a light straw colour, as shown in the Pee Chart below. As mentioned previously pre and post body weight measurement is also important for measuring hydration status.

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