Diploma in Sport Studies

Sports Nutrition

Information Pack

THE UNIVERSITY OF ZAMBIA SCHOOL OF EDUCATION

PHYSICAL EDUCATION AND SPORT UNIT UNZA – Sport Education and Development (SED) Program

Introduction Sports nutrition has become a popular area of interest in recent years, due to the effects that diet has been shown to have upon sporting performance. Both nutrition and hydration strategies have been found to benefit performers in a range of sports. The strategies can be applied to a range of athletes competing at a variety of levels. Individual demands of the sport must be considered when manipulating the diet before, during and after a competition as well as daily throughout training periods. In addition to this for any strategy to be successful it must be supported by all personnel in contact with the performers like the coach, fitness trainers and friends and family. However in order to develop an effective sports nutrition programme for an athlete the basics of healthy eating must be followed first, including the correct balance of macro and micronutrients. With this a basic understanding of the digestion process will also be covered to help understand how the nutrients are used within the body. The aim of this unit is to provide you with a broad understanding of the key nutritional issues, where diet can be adjusted to meet individual sports performer’s needs, and the energy requirements for a range of activities. By the end of this unit you will have the skills and knowledge to understand the role of nutrition in sports performance, including nutrition and hydration requirements and the components of a balanced diet. With this knowledge you will be able to plan a diet for a specific sports activity. On completion of this unit you should:

1. Know the concepts of nutrition and digestion 2. Be able to assess the energy needs of individuals and produce an

effective nutrition management programme 3. Be able to plan and develop an effective nutritional strategy for specific

sports

Section One - Know the Concepts of Nutrition and Digestion Part 1.1: Macronutrients and micronutrients It is absolutely essential for an athlete to learn good dietary and nutritional habits early in their career. For example, bringing the right snacks to training, eating plenty of fruit and vegetables each day, eating regular meals, getting up and having breakfast in the morning, taking a drink to training so they have always got fluid, are all important aspects of a diet that is beneficial for sports performance. A diet can be good or bad for health. The term diet is used to describe a pattern of everyday eating habits and does not necessarily mean someone who eats healthily. If we are to stay healthy, the food we eat that makes up our diet should be made up of 5 major classes of nutrients as well as water:

• Carbohydrate (to include fibre) • Fat • Protein • Vitamins • Minerals and trace elements • Water

Macronutrients are nutrients that provide the body with energy. These are carbohydrates, fats and protein Micronutrients are required in much smaller amounts by the body and these are vitamins, minerals and trace elements Carbohydrates Carbohydrate is perhaps the most important macronutrient for energy, because it is this food group that is most easily converted to energy for sports performance. It is also the most used energy source in the body. As a result, 55% to 60% of a person’s total daily intake should come from carbohydrate. The percentage needs to be higher if the person is training or in competition. Most of the cells of the body can use a mixture of carbohydrate and fat for energy but the brain and the nervous system is only capable of using glucose for energy and whatever form carbohydrate enters the body, it is firstly converted to glucose to ensure that the brain has a plentiful supply. The stored form of glucose is known as glycogen – this can be stored in the muscles of the body and in the liver.

Dietary carbohydrates come in many different forms and can be divided into simple and complex sugars most of which can be converted in the body into glucose that is used to produce energy. Examples of dietary sugars

Simple sugars

Complex sugars

Look, taste and feel sweet and sticky: Sugars, sweet drinks (e.g. coke) and sweet foods (e.g. jam, fruit, milk and milk products)

Look and feel dense and starchy: Grains, bread, rice, pasta, potatoes, cereals

It is important to recognise that as far as the body is concerned, there is no difference between simple or complex sugars and there is also no difference in the calorie count. Both simple and complex carbohydrate has 4 kcal of energy per gram. However, a person would need to eat a lot of sugar to feel as full as if they ate a complex carbohydrate meal e.g. bread. The obvious difference is the density (how compact they are) of the Carbohydrate – complex carbohydrates are much denser than simple carbohydrates and so make a person feel fuller. The other difference is the speed with which the sugar is absorbed into the bloodstream. To help quantify the differences that a food makes on the levels of glucose in the bloodstream, a ranking system for food called the Glycaemic Index was developed. Please refer to the Activity 1.1 – Sources of carbohydrate The Glycaemic Index (GI index) The Glycaemic Index is a ranking given to carbohydrate foods based on the effect they have on blood glucose levels. Carbohydrates that break down very quickly during digestion have a high GI, while carbohydrates that break down very slowly have a low GI.

Low GI High GI 100100

Slow absorption of sugars

Fast absorption of sugars

Complex Carbohydrates

Simple Carbohydrates

Each food listed on the Glycaemic Index has a number of between 1 and 100 – the higher the number, the more quickly the sugar is absorbed into the bloodstream and affects blood sugar levels. High GI foods will hold a value of 70 or more, medium 30-70 and low less than 30. The diagram below demonstrates that high GI foods, cause a peak in blood glucose levels then a dramatic fall, however low GI foods prolong a more steady blood glucose profile. For example, oats have a very low GI, while raisins have a very high GI. For this reason, high GI foods are useful for athletes who need to replenish their stores of glycogen directly after training or competition. Conversely, an athlete who needs to stock up on glycogen prior to a race (known as carbo loading) might eat lots of low GI foods to ensure that there is a steady release of sugar throughout the race. Please refer to Activity 1.2 - Glycaemic Index Fibre Some complex carbohydrates, such as those found in fruit and vegetables, are difficult to break down and in some cases impossible. They form what is called dietary fibre which is essentially the skeleton of plants (such as bean skins and the outside case of corn). This aids bulk to the faeces and helps food move through the digestive tract more efficiently, decreasing time in the system.

Fibre is essential to a healthy diet, although it cannot really be called a nutrient because the body does not absorb it. Fibre improves gut function and helps food quickly travel through the system, as well as aiding absorption of other nutrients. Fibre has been proven to help to reduce problems such as bowel cancer, constipation, diarrhoea, and coronary heart disease (CHD). Foods high in fibre include: beans, bananas, peeled apples and pears, oats, carrots, pumpkin, paw-paw, potatoes Fats The recommended intake of fats as part of a person’s total daily intake is 30%. However, recent research has suggested that in the Western Culture it is probably close to 35% because it is so difficult to avoid high fat foods in a Western European daily diet. The fast food culture is also developing rapidly in African countries therefore it remains a key nutrient to monitor and should be maintained at no more than 30% of the total daily intake. Despite this it must be remembered that fat is not necessarily bad for a person but is in fact an essential part of a healthy diet. Fats are widely distributed throughout the cells of the body and have a range of functions:

• They are stored in the body in adipose tissue and act as a fuel for cells and an energy reserve. Every gram of fat is worth 9 Kcal of energy and so the stores of fat in the body are a huge reserve of potential energy. Essentially, every pound of body fat equates to 3500 Kcals of energy, so even a person with very low body fat has a huge reserve of energy stored as fat

• They are carriers for fat soluble vitamins and essential fatty acids, and

they provide a protective layer around vital organs

• They help insulate the body against heat loss and are part of the structure of brain and nervous tissue, as well as the cell membranes of every cell in the body. Diets too low in fat intake can cause problems such as osteoporosis (brittle bone disease)

• They are involved in the production of hormones within the body, so

they affect a whole range of body functions. This is particularly important for women because reproductive hormones (especially oestrogen) are stored in fat – women with a very low body fat might compromise the function of the reproductive system

• They have a large role to play in the structure of skin and hair – a diet low in fat can make hair seem dull, and skin seem grey and dry

Classification of fats Fats can be classified depending on their source and characteristics: Saturated fats These mainly come from animal sources and are usually solid at room temperature. Examples would be butter, lard, cream, fat in meat and meat products. A high consumption of saturated fats may lead to weight gain and cardiovascular diseases. Unsaturated fats Unsaturated fats fall into two categories: Polyunsaturated fats: These come mainly from plant sources and are usually liquid at room temperature. Examples would be sunflower oil and fish oil. Monounsaturated fats: These mainly come from a non-animal source and are usually liquid at room temperature. When these oils are cooled they will become more viscous. Examples would be olive oil and avocado oil. The majority of fat sources should come from this type of fats, as these are essential to the bodies needs. They are mainly responsible for maintaining our immune system. Essential fatty acids can be found in fish, oils and meat. Trans fats Trans fat is the name given to an unsaturated fat that is chemically altered by a process called hydrogenation into a solid oil. The problem with this process is that the process of hydrogenation actually turns unsaturated fat into saturated fat or trans-unsaturated fat, which is the type of fat that normally needs to be reduced as part of a healthy diet. It can be found in a lot of processed foods such as spreads, cakes and biscuits. Fat issues Excess fat intake is a risk factor many diseases such as coronary heart disease and can lead to conditions such as diabetes and obesity. In terms of sport nutrition, fat is used as a fuel supply in low intensity long duration exercise, however excess body fat is not useful for any sport with the exception of sumo wrestling!

The approximate recommended daily allowance (RDA) for fat intake is: Fat intake Men Women Total fat 90g 76g Saturated fat 10g 8g Trans fat 1.8g 1.5g Source: British Nutrition Foundation, 2006 Proteins Proteins are necessary for the healthy growth and repair, structure and functioning of the body. About half of all body protein is found in tissues such as muscle and skin. Although protein is not an ideal source of energy, it can supply 4 Kcals of energy per gram. Protein is usually plentiful in European diets and many African foods such as Beans are high in protein content. There are several roles of protein:

• All enzymes are proteins - they are involved in chemical reactions that take place in the body

• Proteins are involved in oxygen transport and muscle contraction

• Some hormones such as insulin are proteins

• Proteins also play a part in the immune system (antibodies are

proteins)

• Proteins can be used as an energy source by the body but this requires the breakdown of protein structures like muscle (gluconeogenesis). This mainly happens when calorie intake is too low for too long. An example would be where an athlete is competing in an endurance event and has not fuelled efficiently by eating carbohydrate

With protein, more is not better. A high intake of protein can cause kidney and liver disease, and high levels of protein cause an accumulation of ammonia in the blood, which can damage brain cells over a long period of time. As a result, the recommended intake of protein as part of a healthy balanced diet is 10% to 15%. This figure will rise slightly for athletes who predominately complete strength work as part of their training programme.

As a guide, the table below summarises recommended protein intake. Type of person Recommended protein intake Sedentary person 0.8g per Kg body weight Endurance training athlete 1.2 – 1.4g per Kg body weight Strength training athlete 1.2 – 1.7g per Kg body weight Protein intake of over 2g per Kg body weight has been proven to have no benefit for any athlete. The structure of protein Proteins are made up of amino acids. There are 20 different amino acids and these are combined in different ways to form protein.

Essential / primary amino acids

There are eight essential amino acids – the body cannot

manufacture them and so they must form part of a healthy diet

Non-essential / secondary amino acids

There are twelve non-essential

amino acids – the body can manufacture them if they are in

short supply

All 20 amino acids are needed to allow the many combinations of proteins to be formed in the body. However, some sources of protein have better supplies of amino acids than others.

Sources of amino acids

Not every source of protein contains all of the essential amino acids needed by the body. Animal sources of protein do contain all of the essential amino acids a person needs but some plant sources of protein do not include the full complement of essential amino acids. This is especially important when considering athletes who might be vegetarian, because a diet plan for a vegetarian would need to include sources of protein that included the essential amino acids. Such foods might be soy beans, or a combination of foods such as beans on wholegrain toast.

Main food sources of proteins

• Animal products (meat, fish, eggs, cheese, poultry) • Vegetable products (peas, beans, lentils, nuts, soya, textured

vegetable protein) • Milk and milk products

Please refer to Activity 1.3: Function of fats and protein Vitamins

Vitamins are crucial to many processes in the body, although they do not contain any energy and are only needed in minute amounts.

Most vitamins cannot be made in the body so need to be obtained from the diet to avoid deficiency diseases. Even those which can be made (such as vitamins D and K), may not be made in the correct quantities and so a healthy diet is very important to ensure that requirements for vitamins are met. While many vitamins can be found in animal sources of food, it is recommended that vitamins also come from fruit and vegetables. Vitamins can be divided into two groups:

Fat soluble: Vitamin A • Needed for normal development of body tissues and for normal

adaptation of the eyes to the dark • Main food sources in the UK are meat and meat products (which provide

most of our intake), milk and dairy products and fat spreads

Fat soluble vitamins A, D, E, K

Water soluble vitamins B, C

• The best food sources of the animal form of vitamin A (retinol) are liver and liver products, kidney and offal, oily fish and fish liver oils and eggs. Best food sources for the vegetable form (carotene) are carrots, red peppers, spinach, broccoli and tomatoes

Fat soluble: Vitamin D • Can be synthesised in the body from the action of ultraviolet light (e.g.

sunlight) on the skin

• Dietary intake is only essential for those with no access to the sun (such as the housebound), or those who cover their skin completely (certain ethnic groups. Due to the strength of the sun in African countries

• Vitamin D is involved in calcium absorption and is therefore essential for

healthy bones • Most dietary vitamin D in the UK comes from margarine and fat spreads,

cereal products and oily fish. Some foods are fortified with vitamins – margarines and fat spreads, breakfast cereals and some dairy products

Fat soluble: Vitamin E • Helps to prevent damage to fat-containing structures such as the

membranes of all cells. Deficiency of vitamin E is rare • The main food sources in the UK are fats, meat, fish and eggs Fat soluble: Vitamin K • Needed to help blood to clot. It can be made in the body by bacteria in

the gut, so deficiency is rare • Main food sources are green leafy vegetables like cabbage and beef Water soluble: B Group vitamins • Includes vitamins such as thiamin, riboflavin, folate, and niacin. They are

involved in energy metabolism and other metabolic processes • They are widely distributed throughout the food groups; many breakfast

cereals are fortified with these vitamins

Water soluble: Vitamin C (also known as ascorbic acid) • Involved in many specific metabolic processes including iron absorption.

Vitamin C also acts as an antioxidant often with vitamin E. It is also needed for the structure and maintenance of blood vessels, cartilage and bone. Deficiency is rare, though smokers have a higher need of vitamin C than non-smokers

• The main food sources in the UK are vegetables, drinks especially fruit

juices and fruits Minerals and trace elements • These are needed in small or trace amounts and are essential for normal

bodily function • They are needed for tissue structure (such as calcium and phosphorus in

bones and teeth, and iron in blood haemoglobin), enzyme systems, fluid balance (sodium and potassium in body fluids), cell function, and neurotransmission (potassium is involved in nerve function)

Calcium • Needed to build and maintain skeletal structures. 99% of body calcium is

found in bones and teeth where it gives rigidity. 1% is found dissolved in tissues and fluids, where it plays a vital role in functions such as blood clotting, muscle contraction and nerve transmission

• Calcium intakes are often lower than recommended, especially in 16-18

year olds of both genders, and more so in females than males across the age groups. This may reflect concerns about body weight and the mistaken perception of dairy products as being very high in fat

This is of concern because a failure to achieve maximum bone density may increase the risk of developing osteoporosis (brittle bone disease), in later life. Main food sources of calcium

• Milk and dairy products (e.g. cheese, yoghurt and fromage frais) • Cereals (fortified with calcium) • Vegetables (mainly green leafy vegetables) • Meat and meat products • Fruit and fruit juice • Fish (with soft bones e.g. tinned pilchards, sardines) • Pulses (baked beans, dried lentils) • Tap water in hard water areas

Iron • Major role is as an oxygen carrier in haemoglobin (blood), and

myoglobin (muscle). It is also involved in many processes including energy production. Dietary iron comes in two forms, haem and non-haem. Haem iron is the haemoglobin and myoglobin of animal foods like meat

• The most concentrated food sources are red meat, liver and offal meat, with smaller quantities in poultry meat and fish

• Non-haem iron has variable absorption. Tea, eggs and some plant

components can affect its absorption; vitamin C can increase it • Lack of iron reduces the ability to transport oxygen around the body,

and in children can delay and impair mental and motor development Main food sources of iron

• Breakfast cereals (fortified) • Green leafy vegetables • Pulses • Dried fruit, nuts and seeds • Bread and cereals made in the UK (white flour is fortified with iron)

Please refer to Activity 1.4: Micronutrients Fortifying foods Fortification involves the addition of nutrients, to supplement the nutrients already in the food. It was introduced in the UK to improve the nutritional status of a population and is also being used in a number of African countries. The types of nutrients added to food include vitamins, minerals, fibre and proteins. The choice of foods will be determined by the needs of the local population Please refer to Activity 1.5: Fortifying African foods

Components of a balanced diet

A good balanced diet needs to compromise of a number of different factors. As well as meeting the needs for macro and micronutrients as detailed above the following guidelines could be considered as a starting point for a healthy diet.

• Enjoy food • Eat a variety of different foods • Eat the right amount to be a healthy weight • Eat plenty of foods rich in starch and fibre • Not eat too many foods that contain a lot of fat • Not have sugary foods and drinks too often • Look after the vitamins and minerals in food • Limit alcohol intake

The model is a plate model to help people to understand the proportions of their food intake that should come from the different foods. See Fig. 1 The Balance of Good Health applies to everyone, regardless of body weight, but it assumes people are in good health. It is intended as a guideline to ensure that nutritional needs for vitamins, minerals, and trace elements are being met. It was originally developed for the UK however with the task below it will help you contextualise it for your current eating habits. Fig. 1 (Food Standards Agency, 1994) Please refer to Activity 1.6: Balance of good health.

The food pyramid A similar diagram has been produced in form of a pyramid, showing a similar contribution of nutrients but also highlights the number of portions recommended.

Please refer to Activity 1.7: Food pyramid

The food groups Looking at each group in turn, the nutrients supplied by each group are as follows: Food Group

Foods Principal Nutrients

Bread, other cereals and potatoes

Bread, rice, pasta, potatoes, maize, cassava chapattis, pitta bread

Carbohydrate energy

B-group vitamins

Dietary fibre

Fruit and vegetables

All fruit All vegetables Fruit and vegetable juices

Vitamins and minerals Dietary fibre

Milk and dairy Milk, cheese, yoghurt, fromage frais Crème fraiche

Protein Fat and fat soluble vitamins (full fat only) Calcium

Meat, fish and alternatives

Meat, poultry, fish, cheese, eggs Peas, beans, lentils, soya

Protein Fat Iron (red meat) Zinc, B vitamins

Foods containing fat; foods and drinks containing sugar

Sugary and fatty snacks and drinks

Butter, margarine, spreads, cooking oils Alcohol

Fat

Sugar Alcohol Salt

Portion sizes As well as the foods within each group and the visual proportions of the ideal diet, the model also provides information on the portion sizes of each food and the number of portions per day we should be consuming. From this information it is possible to compare current intake with what is recommended so that a plan of action can be developed. Food Group

Portion Size Portions Per Day

Bread, other cereals and potatoes

1 slice bread 1 cup of Nshima 1 medium potato 75g dry rice 75g dry pasta 1 medium chapatti

At least 6 per day, more if active

Fruit and vegetables

1 piece whole fruit 1 cup salad ½ cup cooked vegetables 1 cup chibwabwa

At least 5 a day

Milk and dairy 200mls milk 25g cheese 50g half fat cheese 100g cottage cheese 1 small pot yoghurt

2 - 3 per day

Meat, fish and alternatives

75g cooked meat and poultry 100g cooked fish 1 – 2 eggs 125g cooked beans, lentils

2 servings

Foods containing fat; foods and drinks containing sugar

Eat sparingly

Please refer to Activity 1.8: Portion sizes

Recommended macronutrient intake Based on the information already covered, a healthy balanced diet for an active individual should include:5 to 60% of total intake from carbohydrates. 60% Carbohydrate 10 % Protein 30% Fat

Within this intake a good balance of the following should also be consumed. Vitamins Minerals Fibre Water Recommendations for achieving a healthy diet

• Although it is sometimes difficult to achieve the recommended dietary intake, there are some things that most people need to take on board in order to work towards the balance of good health. This is the same for sedentary people and sports people:

Target

Dietary Change

Reducing saturated fat / trans fatty acids (these are hydrogenated vegetable oils and act like saturated fats in the body)

• Reduce consumption of fried foods, processed meats and meat products e.g. sausage rolls, reduce mayonnaise dressings, cakes, biscuits and crisps

• Swap to low fat dairy products • Choose lean cuts of meat and trim all

visible fat • Reduce consumption of hard vegetable

fats and margarines, pastries, cakes and biscuits

Increasing healthy fats (e.g. omega 3 fatty acids)

• Include at least one helping of fish and preferably ‘oily fish’ each week. Oily fish include salmon, mackerel, pilchards and sardines either fresh or tinned. Only fresh tuna and not tinned tuna, contains ‘Omega 3s’

• Additional plant sources from rapeseed oil, nuts and some green leafy vegetables may also be beneficial

Increasing soluble fibre • Enjoy more fruit and vegetables with skins and seeds where appropriate

• Include porridge oats and oat based snacks, baked beans and other beans and pulses in a daily diet

Moderating alcohol intake (over 18 year olds)

• Consume no more than 21 units for men and 14 units for women a week. Note that many beers and wines now contain more than one unit per half pint or glass. Avoid binge drinking and have at least one alcohol free day per week

Reducing sugar intake (Remember that sugar comes in many forms e.g. honey, glucose, fructose etc)

• Reduce added sugar on breakfast cereals and in hot drinks. Make use of low calorie artificial sweeteners and reduced sugar processed foods

• Use less sugar than stated in recipes • Cut back on refined sugar intake from

sugary foods, cakes, biscuits, sweets, soft drinks

Increasing fruit and vegetable intake Aim for 5 portions of a variety of fruit and vegetables each day

• One glass of fresh fruit juice will count as one portion

• Eat all types of fruit including fresh, tinned, dried, stewed and baked

• Eat fruit with yoghurt, fromage frais or ice-cream

• Serve at least 2 portions of vegetables at mealtimes

Cooking methods When foods get cooked it affects the nutrient content of the food. All foods will reduce in nutrient content for a number of different reasons depending on the cooking method chosen. For example, when boiling foods in water the nutrient content of the food decreases as nutrients get lost in the water. When frying foods using oils the fat content of the food will also increase. Steaming foods tends to be a better option however it involves equipment, which has the food source sitting above (but not in) a pool of boiling water. An example of how cooking methods can affect the vitamin A content of maize when making a maize meal. This is from research conducted in South Africa. Methods and results Two preparation methods usually used by the mothers in the community were used. In the first, 1500 ml water with 2 g salt was brought to the boil. Then 500 g maize meal was added gradually and whisked to prevent formation of lumps. The porridge was left to simmer for 30 min with occasional stirring. In the second method 336 g maize meal was added to 750 ml water with 1 g salt in a pot and brought to the boil while stirring. The lid of the pot was put on and the porridge left to steam-cook for another 30 min. In the first method, 71% of the added vitamin A was retained, and in the second, only 55%. Part 1.2: Local foods and the climate Agriculture and climate Zambia is approximately 56% arable and 44% pastoral; therefore the majority of the land focuses on growing crops. It also acts as a major economic sector for many African nations. Agriculture is becoming an increasingly important sector in the Zambian economy since the mineral sector, which was the backbone of the economy from post-independence times (1964) till the late 1980s, has declined.

The agriculture sector generates about 18% to 20% of the country’s GDP and provides a livelihood for more than 60% of the population. It employs about two-thirds of the labour force. Most of the agricultural production is dependent on rainfall and in Zambia in particular this can be a problem with some areas of the country experiencing floods and other droughts. The increased number of droughts can also be linked to the growing concerns regarding climate change, giving erratic patterns in rainfall. Zambia has experienced an increase in drought frequency and intensity in the last 20 years. Maize production has been variable with some years only producing 40% of their long-term average. Main crops produced and their climatic needs Maize: It’s a high yield grain, which is good for mass production of the crop, however it is cold intolerant and must be planted in spring. It also has a shallow root systems, making it dependent on soil moisture. Therefore in areas of drought maize crop failure could be an issue. It is the main ingredient of Nshima, a staple food in Zambia. The main nutrient is carbohydrate. Cassava: It is the 3rd largest source of carbohydrate in the world and is high in carbohydrate and has virtually no protein. It can also be used to make Nshima, similarly to maize. It does require at least 8 months of warm weather to produce a crop; however it can withstand extremes of rainfall, and in times of drought it loses its leaves to conserve moisture. Cassava cannot tolerate freezing conditions or flooding. Sorghum: this is widely grown in drought prone Zambian areas as it has a key benefit of being a drought resistant crop. Despite this the yields are not as high as maize. It is a grain high in carbohydrate and sits in the top 5 produced in the world. You can also harvest sweet sorghum, ideal for production of sorghum syrup by crushing the stalks like sugar cane or beets. Please refer to Activity 1.9: Newspaper reports and 1.10 A food word search Part 1.3: Digestion

In order to fully understand the principles of nutrition and sports performance, an understanding of the digestive system is crucial. If the way that food is processed is understood, this information can help to identify how diet plans work. Structure and function of the system will be covered fully in the Anatomy and Physiology module; however in Sport nutrition an understanding of nutrient digestion is needed.

Carbohydrate digestion

Carbohydrate is broken down initially in the mouth by an enzyme called amylase and then continues to be broken down through the digestive tract. Carbohydrate whether starch or simple carbohydrate will get converted into glucose before they are used within the body. Excess glucose will be converted to glycogen to be stored in the liver and muscle. This storage is key to sports performance as for the majority of sports the main fuel supply relies on these stores being maximised.

Fat digestion

Fat digestion does not begin until the small intestine, of which the duodenum is the first section. Bile is released by the gall bladder along with an enzyme lipase which helps break down fat. Absorption of all nutrients also begins here. Once fully digested excess fat is taken to be stored as adipose tissue, which can be under the skin or visceral fat that is stored around internal organs. In general the build up on excess fat can cause the body harm. Despite this, stores of fat can be broken down for energy use; however it takes a plentiful supply of oxygen, which is likely to occur during low intensity long duration exercise.

Protein digestion

Protein digestion begins in the stomach where foods are broken down into amino acids using enzymes such as proteases. The proteins depend on the amino acids contained in the foods will then be transported to the destination in the body where they are needed to fulfil their role. Protein can be used for energy in extreme circumstances; however there is no store for this and therefore when protein is used it is breaking down the protein already built into other tissues e.g. muscle.

Section 2: Assessing the Energy Needs of Individuals: Energy Intake and Energy Expenditure Part 2.1: Energy needs

We need energy for three main body functions:

1. To maintain body functions e.g. breathing and digestion 2. For physical activity / movement 3. For growth and repair of muscle and tissues in the body

When a person exercises their body needs to produce energy much faster than it does when it is at rest. The muscles start to contract more strenuously, the heart beats faster to pump blood around the body more quickly and efficiently and the lungs have to work harder. All these processes require extra energy.

During recovery from training and competition energy requirements are also increased because of the need for growth and repair of the muscles used.

It is therefore vitally important that our diet provides all the nutrients needed to produce the extra energy to meet the demands of training and competition.

What is energy?

Energy is the power used to do work (e.g. physical activity/sport) or produce heat or light. People produce energy from a substance in the body called ATP (adenosine triphosphate), which is created from our three energy systems covered in the Anatomy and Physiology module.

Food and drink a person consumes is broken down in the digestive system and absorbed into the bloodstream. The nutrients undergo a series of reactions to produce ATP, which in turn releases energy.

Energy is given off from the body as heat. It is measured in units of heat called ‘joules’. Kilocalories are also used as a unit of energy and tend to be a more popular choice for athletes.

The joule and the calorie are very small amounts of energy so they are usually measured in kilojoules (KJ) and kilocalories (Kcal):

1 KJ = 1000 joules

1 Kcal = 1000 calories

Where:

1Kcal = 4.2KJ and 10Kcal = 42KJ

There are four components of food and drink that can produce energy:

• Carbohydrate – the main source of energy for exercise, mainly used for producing energy in the short term

• Fat - mainly used as a long-term energy store • Protein - can be used to produce energy, but normally only when the

body is severely depleted of its other energy sources e.g. during very prolonged exercise like the last stages of a marathon or long distance cycle race

• Alcohol – mostly absorbed directly into the blood stream. It cannot be

used directly by the muscles for energy during exercise

Different foods provide different amounts of energy:

Energy Source Kcal / KJ Provided

Carbohydrate 4 Kcal / 17 KJ

Fat 9 Kcal / 38 KJ

Protein 4 Kcal / 17 KJ

Alcohol 7 Kcal / 29 KJ

It is important to understand that whilst fat is the most concentrated form of energy, providing over twice as much energy as carbohydrate or protein, it is not necessarily the ‘best’ form of energy for exercise because it is not as readily available and takes longer to produce the energy.

Energy balance

Energy balance is an important principle in understanding how diet (energy intake) and exercise (energy expenditure or output) can affect a person’s body weight.

To maintain current weight or ‘energy balance’ the ideal equation is:

Energy intake = energy output

• When energy intake (e.g. kilocalories consumed) consistently exceeds

energy output, the excess energy is usually stored in the body as fat and body weight will increase

Energy intake > energy output – (weight is gained)

• When energy output (e.g. activity) consistently exceeds energy intake body fat will be used as energy and body weight will decrease

Energy intake < energy expenditure – (weight is lost) Energy expenditure The body expends energy in a number of different ways, the main one being metabolism. This includes the energy costs of staying alive, of breathing, keeping the blood circulating and the heart beating is called the basal metabolic rate or BMR (this is what most people mean when they talk about their ‘metabolism’). A person’s basal metabolic rate is expressed in kilocalories and gives an indication of how many Kcals need to be consumed in a day to survive. However, this is for someone that is sedentary, or does no activity.

Energy in

Energy out

Energy balance

A simple way of calculating basal metabolic rate for a person is to multiply their weight in kilograms by 25 Kcal:

E.g. A person who weighs 75Kg BMR = Weight (Kg) x 25 Kcal BMR = 75 x 25 BMR = 1875 Kcal

These figures assumes no activity is undertaken and is the minimum number of kilocalories required to maintain good health and stable body weight. Other ways to assess basal metabolic rate: Other methods of measuring basal metabolic rate

As well as using the calculation for identifying the basal metabolic rate of a person, there are also more scientific methods that are conducted in a laboratory environment.

Direct calorimetry

This method measures the heat released by a person in an enclosed chamber. As the heat is released it causes a rise in the temperature of water circulating around the chamber. The increased temperature of the water is directly proportional to the basal metabolic rate.

Indirect calorimetry

This method uses a respirometer worn by a subject that measures the amount of oxygen consumed over a given time. Based on the fact that for every litre of oxygen utilised by the body about 4.8 kilocalories are liberated, the total amount of oxygen used in an hour multiplied by 4.8 will give the amount of kilocalories used in an hour. When this figure is multiplied by 24, the total kilocalories used per day can be calculated.

In medical settings, the body surface area of a person is also taken into account when calculating BMR using this method, because the surface area will determine heat loss for a person, which in turn has a critical effect on BMR.

There are many factors that affect the energy expenditure of an individual one of the main ones being physical activity levels.

Physical activity level The more physically active a person is, the more calories they will burn and the more calories they will need to be able to sustain the energy demands of training and competition. The actual amount of calories expended during sport/exercise depends on the factors described previously as well as:

• Frequency - how often a person trains / competes • Intensity - how hard a person trains / competes • Time / duration - how long a person trains / competes for • Type of sport / exercise – different activities use different amounts of energy

As a rough guide, the table below outlines how many additional kilocalories a person would need to cover their energy output and so maintain energy balance. The percentage multiplier can be anything from 5% to 100% depending on an estimate of how active the person is. To calculate how many Kilocalories are needed for activity, the basal metabolic rate is normally multiplied by a percentage, depending on how active a person is. This is known as a person’s physical activity level, or PAL.

Physical activity level (PAL) Percentage multiplier

Sedentary person – someone who probably works in an office and rarely exercises apart from occasional walks around shops at the weekend. This type of person would not consider exercise and activity important.

20%

Moderately active person – someone who is probably either active all day as part of their job or who may cycle / walk to work. They may be a member of a gym or they may play sport on a recreational basis, up to 4 times per week. They could also keep fit as part of a competitive training programme for a predominately skill based sport.

50%

Very active person – someone who either has a very active job such as a builder, or someone who plays sport at a competitive level and trains every day for at least two hours at a high intensity.

100%

E.g. A person who weighs 75Kg and is fairly active (they go to the gym 3 times a week for half an hour) BMR = 1875 Kcal Percentage Multiplier for PAL = 40% = 1875 x 40% = 1875 + 750 = 2625 Kcal needed per day

Age Calorie requirements tend to peak by about 25 years and then decrease with age. Gender and body composition Adult men tend to have less body fat and more muscle than women of the same age and size. Muscle burns more calories than fat does, so men’s need for energy is usually 5-10% higher than women’s. Climate The environmental temperature that a person lives, trains and competes in will have an effect on their BMR. For example, if a person lives in a cold climate, their BMR will be higher to help maintain core temperature. Conversely, a person in a hot climate will have a lower BMR. Genetics Each individual has inherited their own unique blueprint and in part this decides how many calories are needed to function. This is something over which we have no control.

Body shape and size A greater proportion of muscle compared to body fat means that metabolism will be higher. If there is more body fat and less muscle the energy cost of metabolism will be lower and there will be a greater tendency to store fat and gain weight. The bigger the body, the more calories are needed to keep it going. This is because weight gained is not just a gain in fat, but in muscle as well.

Energy intake

The recommended number of daily calories for men and women are:

Men – approx 2,500 Kcals

Women – approx 2,000 Kcals

As a general guide, for the majority of sports performers, these calories should be consumed as part of a healthy diet that is made up of the following proportions:

• 55-60% carbohydrate • 10-15% protein • Less than 30% fat

This recommendation needs to be considered in relation to the UK Balance of Good Health guidelines.

Please refer to Activities 2.1 and 2.2: Energy for Sport and Energy Balance

Measuring requirements

It has already been discussed in Section 1.1 that fat should be an integral part of a daily diet but can also contribute to health problems such as obesity and coronary heart disease (CHD). For sports performance, maintaining correct levels of body fat helps ensure that an athlete performs at their optimum level – too much body fat can reduce power-to-weight ratio which can lead to impaired athletic performance.

Body composition

The human body is composed of many different substances, including muscle, bone, organs, water and fat - each substance makes up a percentage of the whole. Fat makes up an important part of the structure of a human, and there are recommended ranges of body fat as a percentage of the whole body to give a person guidance on what would be classed as a healthy level of body fat. Normally, fat levels are compared to muscle mass levels, because a higher level of muscle mass would normally mean that a person had a lower body fat level and vice versa. This is sometimes called the fat-lean ratio, where lean is classed as muscle mass.

Males Females Minimum body fat percentage for good health 5% Minimum body fat

percentage for good health 12%

Average body fat percentage range

15-18%

Average body fat percentage range

22-25%

Body fat percentage that could cause associated health problems

>25% Body fat percentage that could cause associated health problems

>32%

Athletes tend to have a higher lean tissue mass (more muscle compared to fat) and so might be at the lower end of the above scale. While low levels of body fat can help sports performance, body composition alone is not a great predictor of sports success. For example, a prop in the sport of Rugby needs to have enough body mass (lean and fat weight) to generate high forces and avoid injury. Body fat among elite athletes varies largely by sport. There is little evidence of any performance benefit when men drop under 8% and women drop under 14% body fat. Indeed, body fat percentages below recommended minimum levels can lead to illness, injury and disease.

For example, a common problem associated with low body fat levels in female athletes is the female athlete triad, where body fat is so low that osteoporosis (brittle bone disease) develops, the menstrual cycle is interrupted and energy levels become very low, affecting performance.

Measuring body composition

Measuring body fat can ensure that a coach or athlete can benchmark the effects of diet plans and training programmes. However, some ways of measuring body fat are more effective than others and a person who wants to benchmark body fat needs to choose measuring tools carefully.

Body weight

Measuring body weight using scales gives a measurement of the total body weight of a person but does not take into account the differences in lean and fat mass of that person. While knowing the total weight of a person might be useful in certain situations, this method should not be used where monitoring body fat is concerned. As a tool for motivation, using scales for measuring body weight might have a negative effect if a person is training, because any gains in muscle will make the total body mass of a person higher, masking any fat loss.

Body mass index

The body mass index is a calculation based on a person’s height and weight, and gives a number that can be compared to a population norm for healthy and unhealthy ranges. While this method can be used for the general population, great care should be taken when applying this method of measuring body composition to athletes, because the index can sometimes give results that would indicate potential health problems even if the person is within healthy ranges for their sport performance. Increasingly, the use of BMI has been questioned by some health professionals, although it can still be a useful tool in certain situations.

To calculate a person’s BMI, the following calculation should be used:

E.g. A person weighs 70 Kg and is 1.8 metres tall

BMI = _70 Kg_ 1.8 x 1.8 BMI = _70_ 3.24

BMI = 22

The following table gives an indication of how a person’s body mass index would indicate their body fat mass:

Category BMI Underweight Below 18.5 Normal 18.5 – 24.9 Overweight 25 – 29.9 Obese 30 and above

Skinfold analysis Analysis of body fat using skinfold callipers can be an accurate method of measuring actual fat loss, as they can determine between fat and lean muscle tissue. However, the measurements do need to be taken by someone who is experienced at using the callipers to ensure accuracy. Callipers can also be quite intrusive, especially if a person feels self conscious, because they involve the subject having to be measured around the torso and arms. Care also needs to be taken with the choice of calliper - cheap callipers often result in less accurate readings although more accurate callipers may be very expensive. Measuring body fat using skinfold measurement can therefore help to benchmark levels of body fat in a person but an inexperienced measurer might not produce results that can be compared across a number of tests. There are a number of different approaches to measurement, dependant on the number of sites on the body used. Bioelectrical impedance analysis

This method of analysing body fat measures the level of resistance of current through the body. Since water conducts electrical current well, those tissues with higher water levels (muscle) conduct electricity better than those with lower levels (fat). By determining the impedance to electrical current flow, an estimate is made of the percentage of fat in the body. This measurement is quite accurate, but is affected by the level of hydration of a person, so a person who has drunk alcohol, caffeine or exercised within the previous 12 hours may be dehydrated and not get accurate readings.

Weight (Kg) (m) Height (m2)

Females may get different measurements at different points of their menstrual cycle due to water retention. The level of current that is passed through the body is very low.

There are various types of bioelectrical impedance machines. Some use electrical contacts that attach to hands and feet, while others are integrated into normal weighing scales so that a person’s bare feet rest on electrical contacts to allow a current to be passed through the body.

Hydrodensitometry

This method is also known as hydrostatic weighing or underwater weighing, and is considered by most professionals to be the gold standard of body fat measurement.

The method requires the use of a tank that allows the subject to be measured underwater. A comparison is made between the underwater weight and the dry weight of the subject, taking into account the residual volume of air in the lungs, which affects buoyancy. Because fat is less dense than the other tissues in the body, it floats more easily. The more fat an athlete has, the greater the difference between the dry and wet weights. While this method of measuring is very accurate, it is also time- consuming, labour intensive and very expensive.

Please refer to Activity 2.3: Body composition and sport performance

Part 2.2: Assessing energy intake

Monitoring food intake is essential to ensure that athlete are consuming the correct proportions of nutrients in their daily diet and to check that they are making the correct amendments on training and competition days.

Keeping a food diary

Day 1 ______________________________________________________________________________

Day 2 ______________________________________________________________________________

Day 3 ______________________________________________________________________________

Day 4 ______________________________________________________________________________

Day 5 ______________________________________________________________________________

A good food diary will give a person who is planning a diet a good idea of eating habits, daily kilocalorie intake and diet mistakes

• The food diary should record Energy In… Everything eaten and drunk during the day

• Everything should be recorded as soon as it’s consumed, so that nothing is forgotten

• Recording quantities eaten will help identify kilocalories consumed - even rough household measures will be useful (bowl, plate, teaspoon and so on)

• A food diary should be an honest record - usual intake should not be altered

• The food diary should be a record over several days – a diet may be quite different at weekends for example

• The food diary should record the times a person eats – this may help identify trigger times for snacking

• The food diary should record how a person feels when they eat. What feelings cause them to start eating? Emotions are often potent triggers – boredom, sadness - recording those will also help to identify triggers

Once a food diary has been recorded, a diet planner can use this information to gauge how many kilocalories a person is roughly consuming in a day, and where those kilocalories are coming from.

Ideally after analysis of the food consumed you should be able to estimate the kcal in the meal, and g of protein/carbohydrate and fat using nutrient values from the internet and food labels. However the activities you will be able to do relate to portions of foods, as this is easier to do and acts as a good starting point for dietary analysis.

Kcal Protein (g) Carbohydrate (g) Fat (g)

Breakfast 1 average bowl muesli

200ml skimmed milk

1 small glass orange juice

220

66

54

6

7

1

40

10

9

5

0

0 Mid-morning

2 apples

94

1

24

0 Lunch

1 baked potato

1 tsps olive oil spread

1 bowl salad

1 tbsp oil/vinegar dressing

2 kiwi fruit

306

85

15

99

59

9

0

1

0

1

60

0

2

0

13

0

9

0

11

1

Mid-afternoon

1 orange

1 carton yoghurt

59

135

2

6

14

27

0

3 Training session

500ml juice, 500ml water

180

3

40

1

Post-training

2 bananas

190

2

48

1 Dinner

1 portion grilled chicken

85g pasta

176

296

36

10

0

64

4

2

with 1tbsp olive oil

1 Large portion broccoli

1 Large portion carrots

2 tbsps pasta sauce

99

30

30

14

0

4

1

1

0

1

6

4

11

1

1

2 Evening snack

1 portion red grapes

48

0

12

0 Total 2284 91 374 52 % energy 15 65 20

N.B. The number of Kcal and amount of protein, carbohydrate and fat per food item shown is an approximate value only

To work out the energy percentage from each food source do the following calculations:

a) Total amount of food source (g) x amount of Kcal per gram of food source = amount of energy obtained from food source (g)

To work out the % do the following calculation:

b) 100/total Kcal consumed x amount of energy obtained from food source = % energy per food source.

e.g. To work out the % energy of protein consumed:

a) 91g x 4Kcal = 364 b) 100/2284 x 364 = 15%

To work out the % energy of carbohydrate consumed:

a) 374g x 4Kcal = 1496 b) 100/2284 x 1496 = 65%

To work out the % energy of fat consumed:

c) 52g x 9Kcal = 468 d) 100/2284 x 1496 = 20%

There are also a number of dietary analysis software packages available that can be used to plan and analyse meals for effective sports performance. Although these vary in the information that can be gained, most will allow a person to calculate the above. Please refer to Activity 2.4, 2.5, 2.6, 2.7 and 2.8: Food diaries

Section 3: Planning and Developing an Effective Nutritional Strategy for Sport Part 3.1: Demands of different sports

The main dietary goal for a sports performer in training is to follow a well balanced diet that will meet the additional nutrient and fluid demands that the training requires.

This means that it must be a healthy diet that allows the sports performer to:

• Train hard • Recover • Maintain the ideal body weight for the specific sport

For a person to be able to plan a diet that is appropriate for a selected sports activity, they must be able to understand the demands of the activity, the period or season of the sport that the athlete is in and the actual needs of the performer. Only when this information is collated, can a person begin to plan a diet effectively.

Types of activity and their energy needs

Any activity uses a number of sources of fuel in order to produce what is known as the ‘energy currency’ – ATP (Adenosine Tri Phosphate). The role of any energy system in the body is to re-assemble ATP once it has been broken down to create energy.

Any energy system will take ADP (Adenosine Di Phosphate) and Phosphate, and will re-assemble it to form ATP again. However, different types of activity will place demands on different energy systems, depending on the intensity of speed of the activity.

Aerobic activity

During aerobic activity, the workload placed on the body is of a level that means the cardio-respiratory system can keep up with demand. In other words, the intensity of the activity means that energy can be supplied from the aerobic energy system.

The aerobic energy system is perhaps a human’s most efficient way of producing an abundance of energy, because it relies on a number of readily available fuels including oxygen, fat and carbohydrate. Through various processes, fuels are consumed and used to produce a high number of ATP. However, all of these fuels must be available in order for the aerobic energy system to be able to resynthesise ATP.

This fact is crucial when considering nutrition, because the aerobic energy system cannot burn fat resources if there is no carbohydrate present. For this reason, it is essential that there is a ready supply of carbohydrate available in the working muscles, in the form of glycogen.

A person taking part in aerobic activity must therefore have sufficient stocks of glycogen in the muscles if the aerobic energy system is to be used efficiently. Carbohydrate stores are small in the liver and working muscles, and so topping up glycogen stores during prolonged aerobic activity is very important if fat stores are also to be utilised together with oxygen. A diet plan for a sportsperson that predominately takes part in aerobic activity must ensure that there is a good source of carbohydrates throughout the day. This ensures that glycogen stores in working muscles are always stocked up, ready for activity. Of course, the diet also needs to contain quality sources of fat to ensure that fat stores of energy are maintained, together with protein for muscle repair after exercise and all other associated vitamins and minerals to ensure that chemical reactions needed to re-build ATP can take place. The fitter a person is, the better they also become at utilising fat during aerobic activity.

Remember – fat is not used if there is no carbohydrate present. This is especially important to consider where an athlete is looking to lose body fat, because in the absence of sufficient glycogen stores, fat stores cannot be used – the body will use the next available source of food, which is normally muscle protein. This actually means that the very muscle being trained will be digested to keep the body moving – not a good thing for a sportsperson!

Anaerobic activity

During anaerobic activity, the cardio-respiratory system cannot supply oxygen quickly enough to working muscles, and so ATP is resynthesised anaerobically (without oxygen). Whichever anaerobic energy system is used to achieve this, glycogen must still be present in order to rebuild ATP. However, the speed at which this supply is used will depend on the speed and intensity of the activity and is prolonged by using other fuels such as creatine phosphate. As with aerobic activity, the harder a person works, the more fuel is used – this also means that glycogen is depleted more rapidly.

Muscular strength and endurance

During any muscular strength and endurance training, there is normally a combination of the aerobic and anaerobic energy systems used. As a result, if the aim of a sportsperson is to gain lean muscle, then they should still consider a balanced diet, because if there are not enough kilocalories in the diet from quality carbohydrates, the body will digest muscle protein – this obviously undermines any training gains made.

If training volume is increased for these types of activity, kilocalorie requirement will rise and so again, quality carbohydrates need to be considered as the main part of the diet plan so that muscle protein is not digested.

Achievable lean muscle tissue gains are approximately 0.5 – 1 Kg per month, if following an effective strength-training programme.

Finally, as previously mentioned, consuming more protein will mean that the body has to work hard to convert protein to useable glycogen, because this is what is normally demanded. Any excess protein could lead to health problems and has been proven to have no positive effect on fitness when consumed in large quantities. Carbohydrate should always be the main source of fuel in a sportsperson’s diet.

Flexibility

Flexibility training normally includes some form of warm up activity which will place demands on the aerobic energy system. This means that fuel must be available for the activity, to ensure that muscles are warmed effectively prior to flexibility work. Ensuring sufficient levels of carbohydrate when doing flexibility work will also ensure that a person can concentrate effectively on technique, which is crucial for effective flexibility gains.

To ensure that the structures associated with flexibility (tendons, ligaments, cartilage etc) are able to withstand being stretched, it is also important that correct levels of protein and important minerals such as calcium are maintained in the diet.

The energy continuum

Please refer to Activity 3.1: Demands of the sport

Anaerobic activity

Aerobic activity

100m sprint Marathon Boxing 3000m run 800m run 400m swim

Carbohydrate, Oxygen, Fat

Carbohydrate, Creatine Phosphate

Timing of an activity and its impact on diet

Finding out the best nutritional strategy to enable a person to perform their best in training and competition will take trial and error.

For any training programme, regardless of the sport, it is best to consider the balance of good health. As a general guide, the following tips should be considered as recommendations for a sportsperson:

• Consume plenty of complex carbohydrate foods, ensuring to obtain a variety of nutrients to meet the Balance of Good Health

• Eat regular and frequent meals (e.g. 5-6 smaller meals each day)

• Spread intake throughout the day

• Aim to consume a light meal 2 hours before training or a large meal 4 hours before training

• Refuel effectively after training. Aim to consume 1g of CHO per Kg body weight

• Prior to the event follow a carbohydrate loading programme

A carbohydrate loading programme ensures that glycogen stores are topped up effectively prior to competition, which helps avoid glycogen depletion during the event.

As a general guide for carbohydrate loading:

• In the week running up to the event the volume of training should decrease

• During this period a high carbohydrate diet should still be consumed

• Aim to consume 7–12g of carbohydrate per Kg body weight

• The amount of carbohydrate to be consumed will depend on the duration of the event

Pre-season and post season

During pre-season training, the amount of kilocalories consumed by a person might have to decrease or increase, depending on where they are in the training programme. For example, if a sportsperson was increasing training load in the fitness build up to the start of the season, kilocalorie intake would need to be increased to reflect the additional demand. Conversely, if an athlete was in the recovery phase of a programme after a competitive period, then kilocalorie intake might need to be decreased because activity levels would probably be lower. Above all though, the balance of good health should still be considered, to help recovery, repair and general well-being.

Mid-season

During the mid-season phase of a programme, nutritional requirements will vary depending on the sport. Importantly, a diet plan should consider fuels needed for recovery, the number of competitions within the competitive season and the optimal performance weight for the sportsperson.

It is important to maintain the balance of good health for optimal performance through the competitive season, but the increased demand for kilocalories that comes with competitive sport should also be considered – eating habits might need to be altered to fit into punishing training and competition schedules, to ensure that sufficient quality kilocalories are being consumed.

Pre-event

A sportsperson will need to experiment to find out what works best for them – many athletes like to consume a small snack about an hour before exercise (e.g. banana, cereal bar, malt loaf, jaffa cakes etc), but care should be taken to consume quality carbohydrates that top up glycogen supplies without affecting the balance of good health.

If a sportsperson eats a large meal then they will need to wait about 2-4 hours before exercising, to ensure that food is digested and blood supply is not being mainly utilised for digestive system function. This will also ensure that nutrients are absorbed effectively, ready for the activity.

Inter-event

A sportsperson will need to experiment to find out what works best for them – if they compete or train for more than approx 60min it may be necessary to consume a simple carbohydrate snack to ensure a ready supply of energy (e.g. sports drink or energy bar etc).

Post-event

A sportsperson should aim to eat and/or drink carbohydrate-rich energy sources as soon as possible after training or competition e.g. eating a banana, jaffa cakes or having a sports drink in the changing rooms or on the way home.

To be able to train regularly at high intensity the sports performer must have recovered from the previous session. Recovery is helped by what and when an athlete eats and drinks after exercise.

During the first two hours after exercise, glycogen (energy) is restored more quickly to the muscles. Sports performers should therefore be encouraged to eat and/or drink carbohydrate-rich energy sources as soon as is practically

possible after exercise. This means starting to re-fuel in the changing rooms or on the way home rather than waiting until later.

This helps to ensure that the body’s glycogen stores are quickly topped up for the next training session.

Please refer Activity 3.2: Timing of nutrients

Planning a diet for a selected sports performer

The first and most important thing to do when planning a diet for a selected sports performer is to talk to them about what it is they are trying to achieve. Ideally, an idea of the sportsperson’s normal diet should be gained – this could be achieved by asking them to complete a food diary for a few days, so that their normal kilocalorie intake can be gauged. If this is linked to the knowledge gained about the demands of their sport, then the framework of a diet is very easy to plan.

Assessing the needs of the performer

Weight gain: Care needs to be taken with weight gain – it is important to identify where the increase in weight will come from. Ideally, weight gained will be from increased muscle mass, although this is not always ideal for certain sports and might be difficult for sportspeople for would struggle to increase muscle mass because of their genetic make-up. Muscle also weighs heavier than fat, and so small gains in lean muscle will actually increase total body weight in large steps.

Weight loss: As with weight gain, care needs to be taken to identify where the loss in weight will come from. For a sportsperson, it is obviously not advisable for them to lose muscle mass unless they are training for a sport that requires a lean physique rather than a physique which is mesomorphic. Ideally, any weight loss should normally come from fat loss unless the person already has a very low body fat percentage.

Muscle gain: In order to increase the amount of lean muscle tissue, a training programme must combine effective strength training programme with effective nutrition.

It is essential that the volume of training is adequately supplemented with enough kilocalories if muscle development is to take place. An increase in training must result in an increased energy intake – as mentioned previously. If energy intake is not enough to sustain the level of training the result will be loss in lean muscle tissue.

As well as an effective training programme for muscle gain, there are other physiological factors that will determine the amount of weight gain achievable. These are:

• Genetics

• Somatotype

• Hormone levels

The genetic makeup of a sportsperson will determine their muscle fibre physiology and body type, which will play a huge part in how their body will develop lean muscle tissue. If genetics do not favour lean muscle tissue gains the best training and nutrition programme will not reverse this.

It is also worth considering that the male sex hormone testosterone has a huge part to play. Individuals who have naturally higher levels of this hormone will lay down more lean muscle tissue in response to training. This explains why females will find it difficult to develop lean muscle tissue even in response to strength training.

Fat gain: Fat gain is not normally associated with sports performance, although athletes who need to gain body fat because of health problems might attempt fat gain. Great care should be taken when planning any diet for fat gain, because of the associated health concerns over excess fat intake and storage. However, this is normally only dealt with by healthcare professionals or qualified nutritionists.

Fat loss: Effective fat loss is about balancing energy output against kilocalorie intake:

If more kilocalories are consumed than are used, then any excess Kilocalories will be converted to fat and stored.

However, if more calories are used through activity than are consumed in a day, stored fat in the body will also be used for fuel. Importantly though, the balance of good health should not be affected if reducing intake – a balanced diet is still important, even during fat loss.

An effective fat loss programme should have long term fat loss goals, with a safe fat loss of no more that 1 pound of body fat per week.

Fat gain

Kilocalories in

Energy output

Fat loss

Kilocalories in

Energy output

If reducing kilocalorie intake to ensure fat loss, then there should be no more than a 500 kilocalories per day reduction in intake from the recommended intake for the person, based on their basal metabolic rate (BMR) and physical activity level (PAL).

Please refer to Activity 3.3: Assessing the needs of the performer

Part 3.2: Nutrient needs Planning a diet for a selected activity

To plan a diet for a sportsperson, it is important to consider the whole picture before prescribing a plan. Whilst carbohydrate is the most important nutrient for producing a ready supply of energy during sports performance the type of fuel a body uses will depend on different factors. These include:

• Fitness levels – the fitter a person is the more efficient their body is at producing energy/glycogen and utilising fat as an energy source when needed

• How good a person’s diet is – if someone is poorly nourished they may not have a ready supply of energy/glycogen and so may need to break down other energy supplies such as fat and protein to produce the energy needed – this is less efficient than using ready supplies of carbohydrate

Another key factor that determines the fuel used by the body is the type, intensity and duration of exercise.

Look at the following table to see how the duration and intensity of exercise can affect the type of fuel used for energy: Duration of Exercise Major Fuel/s Used

High intensity lasting up to 15 minutes

Carbohydrate (in the form of glycogen)

Moderate-high intensity lasting 15 minutes or more

Carbohydrate (in the form of glycogen) and Fat

As a general rule, the total amount of glycogen used for energy increases as exercise intensity and duration increases. This relationship is shown in the following graph:

• Glycogen is used during virtually every type of exercise, so the more a

person has stored in their muscles the longer they will be able to keep exercising

• If a person’s stores are low at the start of training or competition the earlier fatigue will set in. This will reduce how long they can continue to exercise for and the intensity at which they can exercise at, due to tiredness

• Fat is the other main fuel used to help to meet the body’s demands for energy during exercise. The fat leaves a person’s fat cells and travels to the muscles, where it is also used as fuel. However, although most people have fairly high fat reserves it cannot be converted into energy as quickly as carbohydrate/glycogen and the body cannot keep up with the demand by exercising muscles. The end result is fatigue, where the energy supply does not meet the energy demands

Nutrition considerations for the performer

Carbohydrate is the most important nutrient for sports performance. It is stored in the muscles and in the liver as ‘glycogen’ with about three times its own weight of water – this is one reason why adequate fluid intake during training and competition is so important.

The amount of carbohydrate stored in the muscles and liver as glycogen has a direct affect on sports performance:

• A high muscle-glycogen concentration will allow a person to train at their optimum level and achieve a greater training effect

• A low muscle-glycogen concentration will lead to early fatigue, reduced training intensity and sub-optimal performance

Intensity/Duration of Exercise

Am

ount

of G

lyco

gen

Use

d

Glycogen

If a person does not eat enough carbohydrate their glycogen levels will become depleted and their performance will suffer.

A high carbohydrate diet with an intake of 5-10g/Kg of body weight is recommended for most athletes/sports performers.

It is important to match carbohydrate intake to the requirements of the sport and the individual athlete. The optimum amount will vary according to the type of sport, intensity, duration and frequency of training and competition. For example, strength and power athletes may not require as much carbohydrate as endurance athletes but they still need to ensure correct timing of food intake and that an adequate amount of carbohydrate is consumed to support their training and performance.

The average person actually stores the equivalent of about 1600-2000 Kcal of glycogen – this is enough to last about one day.

If too little carbohydrate is consumed over a long period of time it can increase the risk of injury because skills such as co-ordination and balance are affected. In severe cases it can even contribute to chronic fatigue and the overtraining syndrome.

The other macronutrients also need to form part of the diet plan, but in their respective quantities. Remember that fat stores are used as fuel within the aerobic energy system and protein is used for growth, recovery and repair. This is the same for fibre and micronutrients, whose role in a balanced diet are even more important for a sportsperson for whom optimal function is crucial.

Suitable sources of food groups for the performer

There are a huge amount of nutritional supplements on the market including pills, powders, drinks and bars. These substances are sometimes classed as ergogenic aids (substances that ‘increase work’) and they claim to enhance sports performance in various ways. Different products make different claims, for example to:

• Increase muscle tissue

• Increase endurance

• Promote fat burning

• Improve strength

Since the body can only store a certain amount of glycogen at any one time, like a car, in order to be able to keep going at peak performance it needs to be maintained and re-fuelled.

Common nutritional supplements include:

• Vitamins and minerals

• Protein supplements

• Creatine

• Energy bars

• Sports drinks

It is important that a sportsperson follows a healthy diet to ensure they get the right balance of essential vitamins and minerals for general health and well-being. The role of any person who plans a diet for a sportsperson should be to carefully research any claims that are made by manufacturers of ergogenic aids, to ensure that a healthy diet is still maintained when supplements are being used.

Low body stores or less than recommended intakes of essential vitamins and minerals can negatively affect sports performance. However, taking supplements in excess of normal requirements will not necessarily lead to improvements.

For example, while sports drinks can be a useful means of fluid replenishment, they do provide additional calories, so this is something which must be taken into consideration, particularly for athletes in a weight category sport like boxing or judo.

Typically, pastas, bananas and cereals are good sources of carbohydrate, but eating a wide-range of different carbohydrate foods is useful – bread, potatoes, vegetables, fresh fruit, porridge are good as they all supply a different range of vitamins and minerals. If an athlete were to eat only one or two types of carbohydrate, they would miss out on certain vitamins and minerals which are crucial for optimal function and performance.

Overall, a balanced diet that supplies the correct amount of macronutrients, micronutrients, water and fibre will ensure that a sportsperson performs at their optimal level – any upset to this balance might ultimately have a negative effect on performance. By following a healthy balanced diet a person can help to ensure that their body has adequate energy supplies to meet the needs of training and competition.

Availability of food groups for the performer

Most sports performers need to experiment to find out what works best for them, but a food diary completed by the sportsperson before a new diet plan is devised will give an idea of foods that are available (and enjoyed) by them.

As a result, a diet plan will be very individual, depending on the availability of foods and on the wishes of the performer. However, it is important to try to build-in the following guidelines into their nutritional strategy.

• Meals need to be timed so that they fit around training and competition and this might have an influence on the types of food they feel comfortable eating. For example, a baked potato might be a great source of Carbohydrate, but the sportsperson might struggle to eat this two hours before training if they are at work

• High sugar or simple carbohydrate foods consumed close to exercise can have a negative affect on performance because they increase blood glucose rapidly which can cause a temporary dip soon afterwards (this is called hypoglycaemia or low blood sugar levels). Low GI foods are the best source of slow release energy prior to performance

• Activity level and carbohydrate intake

• There are a number of different methods that can be used to calculate a person’s energy/calorie requirement. The following table can be used to determine how much carbohydrate a person should aim to consume to keep energy levels topped up for training and competition:

Activity Level (at moderate intensity)

Grams of Carbohydrate / Kilogram Body Weight / Day

3-5 hours/week 4-5 5-7 hours/week 5-6 1-2 hours/day 6-7 2-4 hours/day 7-8

More than 4 hours/day 8-10

• Example: An athlete trains for 2 hours each day. Their body weight is 60Kg.

• Carbohydrate needed = 6g-7g / Kg of body weight

• Daily carbohydrate need = 60 x 6 = 360g

• 60 x 7 = 420g

• = 360g – 420g per day

• Foods with lower sugar levels, such as complex carbohydrates, have been shown to produce a sustained source of carbohydrate throughout exercise and recovery and so these should be built into a diet plan throughout the day. Again, the availability of suitable foods should be considered

• In sustained endurance exercise of over 60 minutes, it may be necessary to ‘top-up’ energy stores with a simple carbohydrate snack (e.g. a sports drink/energy bar), to ensure a constant supply of energy – this should be available for the sportsperson, even if they have come straight to training from work or college

• If energy stores are not replenished during sustained exercise sports performers may ‘hit the wall’ or ‘bonk’ as it is known in cycling. This means they have no ready supply of energy and are relying solely on other energy reserves such as fat or protein, which are much less effective. The result can be poor performance

• An intake of between 30-60g carbohydrate/hour is recommended and it is important that it is consumed before fatigue sets in

• If a person eats a larger meal it is advisable to wait 2-4 hours before exercising

• Fluid intake should be built into the daily routine of a sportsperson. Ideally, they should be sipping water throughout the day and so it is a good idea to make sure that they always carry a water bottle around with them

• Many people like to consume a snack about an hour before exercise. As a guide, an ideal amount has been shown to be 1g of carbohydrate/Kg body weight (e.g. 50g of carbohydrate if a person weighs 50Kg)

• The food that a sportsperson eats should be something they enjoy eating. A diet plan that is not enjoyable will have a negative psychological effect on the person and might well affect performance

• A sportsperson should aim to eat regular and frequent meals (e.g. 5-6 smaller meals/snacks rather than the usual 3 well-spaced meals). This will help to:

o Promote glycogen storage, lean tissue repair and growth

o Maintain steady blood glucose levels

o Regulate appetite

o Discourage fat storage

Finally, if a diet plan identifies that a sportsperson should eat lots of organic fresh vegetables, this will obviously not work if the person has a low income or does not live close to a shop that sells organic food. A plan should consider the physical availability of food for the sportsperson as well as the other points mentioned above. However, it is worth encouraging a different approach to purchasing food for the sportsperson, because this will also encourage eating a balanced variety of foods.

Part 3.2.2: Hydration

Water is considered to be a crucial part of a balanced healthy diet and yet is often overlooked when reviewing a person’s needs. Water is the most abundant substance in the body, with up to 70% of a human being made up of water. Even a small loss in body fluid can have a major effect on sports performance and so knowledge of correct levels of hydration and how to maintain hydration is very important for an athlete.

Signs and symptoms of hydration Euhydration Euhydration is the state of ‘normal’ body water content Hyperhydration

Hyperhydration is also known as water intoxication or water poisoning, and is where the normal balance of electrolytes (such as sodium) in the body is taken beyond normal function levels because of a rapid intake of water. This has a dangerous effect on brain function and can lead to death.

Initially, symptoms might include light-headedness, sometimes accompanied by nausea, vomiting and headache. However, a greater loss of electrolytes can lead to seizures, coma and death.

Hyperhydration mainly affects levels of sodium in the body and so a sports person who is losing sodium through sweat but who is only consuming water in large quantities may experience hyperhydration. This is especially true for sports people such as marathon runners. To avoid hyperhydration, fluid consumed for events where fluid loss and fluid intake will be high should include replacement electrolytes to maintain electrolyte balance.

Hypohydration

Hypohydration is also known as dehydration and effectively means the removal of water from an object. Dehydration is a huge performance factor for an elite athlete – if an athlete loses more than 1% of their body weight through fluid loss, there will be a significant decrease in performance.

Dehydration occurs when sweat losses are not adequately replaced by fluid intake. Exercise and hot conditions make people especially prone to dehydration, which can cause many symptoms including tiredness and poor concentration, headaches, nausea and cramps. Exercising in a dehydrated state can make some individuals more susceptible to minor injuries.

Thirst is not a good sign of the need for fluid. Thirst means a person is already dehydrated because the thirst mechanism relies on signals from the body that are relayed when a person is already dehydrated. This is known as a negative feedback system, because negative indicators are used to feed back information to the brain.

Monitoring urine colour can be a useful guide to hydration status. Pale and plentiful urine is a good indication that a person is drinking enough – normally the urine will be a pale straw yellow colour. If urine is dark yellow, this indicates dehydration.

Fluid intake A person should aim to drink at least 2 litres of fluid every day. This figure might be considerably higher for a sports person, with fluid loss being as high as 4 litres per hour for an athlete training or competing at high intensity in a hot environment.

At least some fluid intake every day should be in the form of water – many common drinks like colas and coffee can act as diuretics which means they can contribute to fluid loss, because the digestive system needs to use fluid to process the fluid intake. It is recommended that a person should try to drink weaker teas and coffees and replace some caffeinated drinks with other fluids such as water, herbal or fruit teas, squashes and fruit juices.

However, recent research has also identified that the effects of diuretics are not as bad as initially thought and so are acceptable in moderation as part of a healthy daily fluid intake. Pre-event fluid intake

For effective levels of hydration during a training session or competition, it is important to ensure that fluid is consumed through out the day – drinking large quantities of fluid before exercise will not guarantee effective hydration because only a small amount (typically about 200 ml) of fluid can be absorbed by the digestive system in one go.

As a guide, a person should aim to drink 500mls of water in the 2 hours leading up to the training session or competition, ensuring that the fluid is sipped at regular intervals throughout this time. This will allow for adequate hydration and urination.

Inter-event fluid intake

To ensure adequate hydration during training or competition, or between competitions during an all day event, a person should aim to drink approximately 250ml of fluid every 15 minutes which is equivalent to a few gulps. This equates to approximately 1 litre of fluid every hour, taken as gulps throughout the hour.

Ideally, for exercise over an hour in length the fluid will also include a carbohydrate to maintain glycogen levels in the bloodstream for continued performance. For activity below an hour in length, additional carbohydrate is not normally needed because there is already enough supply of glycogen in the body.

For exercise in hot climates and/or exercise of a very high intensity, even more fluid per hour may need to be consumed.

Post-event fluid intake

After training and competition, it is important to replace any fluid losses, especially where the activity has meant a large fluid loss. Fluid should be consumed as soon as possible after exercise, and should be continually consumed in small amounts for a number of hours after exercise to ensure effective fluid replacement. Remember that the digestive system can only absorb small amounts of fluid in one go, so drinking a large amount of water directly after activity will not guarantee effective rehydration.

If activity has been of a fairly high intensity for a prolonged period of time, it might also be suitable to include a carbohydrate as part of the fluid consumed after training or competition. This will help replace any glycogen lost during activity and will ensure effective recovery.

Sources of fluid

While a person will absorb up to 300ml of water a day from the food they eat (depending on the quality and quantity of fruit and vegetables consumed), a large amount of water still needs to be directly consumed in order to maintain hydration levels. Fluid can come in many forms, including as hot drinks or canned cold drinks. However, for sports performance the following sources are considered the best options for optimum performance.

Water Water is the most suitable drink to have during most exercise and sports. A person should start every exercise session in a well-hydrated state and carry a water bottle, sipping frequently during any activity. They should aim to drink around 100-200 ml during every 15-20 minutes of exercise. Hypertonic sports drinks

A hypertonic drink is a fluid with a concentration of 8 grams or more of carbohydrate per 100mls. Examples would include undiluted fruit juice, Lucozade Energy and Cola. Because of the high density of sugars in this type of fluid, it is not very easily absorbed into the blood stream and can actually sit in the stomach for a long period of time before being absorbed. For this reason, hypertonic drinks should only be used to replace energy in situations where instant energy is not needed. Fruit juices can be converted to hypotonic drinks by diluting half and half with water.

Isotonic sports drinks

Isotonic drinks have between 4 and 8 grams of carbohydrate per 100mls of fluid and are effective hydration fluids because the lower concentration of sugars does not impede absorption of fluid into the bloodstream. This means that the carbohydrate is also absorbed quickly and so an isotonic drink would be useful for maintaining fluid and glycogen levels before, during and after exercise. Examples of effective isotonic drinks include Gatorade, Lucozade Sport, Powerade and High 5. Most isotonic drinks also include added electrolytes to help replace those lost during sweating, and can help avoid hyperhydration. An ideal sports drink would be one that is isotonic and has no more than 6 grams of carbohydrate per 100mls, or a 6% solution.

Hypotonic sports drinks

Hypotonic drinks typically have less than 4 grams of carbohydrate per 100mls of fluid and so have a lower concentration than blood. This means that they are very quickly absorbed into the blood stream and are close in density to water.

Hypotonic drinks can be used for fast hydration without the added burst of energy associated with other drinks that have higher concentrations of added carbohydrate. An example would be 100mls of orange squash diluted with 1000mls of water.

Effects of dehydration on sports performance

As water makes up to 70% of a person’s total body mass, even a slight decrease in levels of body fluid can have a major effect on performance. Water loss can lead to a slower metabolism, headaches, fatigue and even decreased kidney function. A good way of identifying fluid loss is to weigh a person before and after exercise – any weight lost is usually due to fluid loss. The table below gives an indication of how much of an effect fluid loss has on performance. As a guide, approximately 1 Kg of body loss equals 1 litre of fluid loss.

Percentage body weight lost as sweat

Effect on performance

2% Impaired physical sports performance.

4% Ability to concentrate decreases.

5% Heat exhaustion.

7% Hallucinations.

10% Circulation collapses and heat stroke.

The speed at which fluid is lost from the body is influenced by a number of factors: • The frequency of activity within a person’s day – if a sportsperson trains

regularly throughout the day then they will need to ensure that hydration is continual to ensure that hypohydration is avoided

• The intensity of the activity - the higher the intensity, the more fluid is lost to ensure that homeostasis is maintained

• The duration of the activity – the longer the activity, the more fluid is lost. It is important to bear in mind that effective hydration is sometimes difficult for certain sports, especially team sports such a football. For this reason, longer games might mean that a person is dehydrated towards the end because of little opportunity to replace fluid loss

• The specificity of the activity – different activities will cause different levels of fluid loss. For example, playing squash on a hot, enclosed squash court will entail more fluid loss when compared to swimming. An athlete might need to train to cope with performance where fluid replacement is not always available and so would need to consider hydration specific to their sport or particular competition

Finally, progression and recovery of an athlete need to be considered when looking at hydration and fluid loss – it is important to remember that the development of fitness and hence performance in sport is dependant on the body being able to recover effectively from training. If hydration levels are not effectively maintained during and especially after activity, the ability of the body to recover and become fitter will be compromised. As a result, hydration should play a crucial part in the recovery of an athlete. Please refer to Activity 3.4 and 3.5: Hydration and sport drinks Bibliography Bean, A. (2006). The Complete Guide to Sports Nutrition, 5th ed. A and C Black. Denby, N., Baic, S., Rinzler, C. (2005). Nutrition for Dummies (UK Edition). John Wiley and Sons Ltd. Stear, S. J. (2004). Fuelling Fitness for Sports Performance: Sports Nutrition guide. The Sugar Bureau. www.eis2win.co.uk www.nutrition.org.uk