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Nutrition and Fuel Systems for Sport

This is an excerpt from Gold Medal Nutrition-5th Edition by Glenn Cardwell.

Nutrition and Fuel Systems for Sport

He must rise at five in the morning, run half a mile at the top of his speed up hill, and then walk six miles at a moderate pace, coming in about seven to breakfast, which should consist of beef steak or mutton chop, under-done, with stale bread and old beer.

Captain Robert Barclay Allardice's nutrition advice to long-distance walkers (c. 1810)

If I asked you to define healthy eating, you would likely give a very acceptable answer: ‘Plenty of fruits and vegetables, whole-grain cereals . . . include lean meats and dairy foods . . . go easy on the cakes and take-aways'. Basically, this is correct, but it is easy to become confused by what we hear from the media and friends and what we read in books and magazines. As a result, we often go against our basic instincts. This chapter will help you think about what foods to eat both for health and to get the best out of your body, as well as the nutrients in these foods.

Good nutrition is quite simple to achieve. Eat lots of minimally processed foods such as vegetables, grains, nuts, fruits, lean meats and reduced-fat dairy foods (except Camembert and premium ice cream because they taste the best with the fat left in!). Figure 1.1 on page 4 shows the Healthy Eating Plate with the major food groups in the proportion needed for good nutrition and to fuel an active body. This Healthy Eating Plate, from the Commonwealth Department of Health and Ageing in Australia, is very similar to the food guidelines of most Western nations and is especially suited to athletes and other active people.

Food Groups

Foods are divided into groups, each of which provides essential nutrients. The underlying science is well established and similar across every reputable health source, although health authorities sometimes differ in how they name the food groups (e.g., fruit and vegetables might be in separate groups or the same group). Table 1.1 lists the minimum serves recommended from each food group for good health.

Fruit, Vegetables and Legumes

This group should make up about a third of what you eat because it plays an essential role in protecting the body from disease now and in the future. This group is the major source of antioxidants and fibre in your diet. These foods also provide appreciable amounts of essential minerals and vitamins. The legumes can be a major protein source for vegetarians (legumes are beans such as kidney beans, lentils and baked beans). This food group is underconsumed by many people in the Western world. Eating more fruit and vegetables can be the single biggest nutritional improvement many people can make. Around the world, ‘Eat more fruit and vegetables' campaigns encourage people to eat two serves of fruit (about 300 g [10 oz]) and at least 2 cups of vegetables (about 400 g [14 oz]) each day. Australia has the Go for 2&5 campaign (2 serves of fruit and 5 serves of vegetables; www.gofor2and5.com.au), the USA has the 5 A Day campaign (www.cdc.gov/nccdphp/dnpa/5aday/) and the UK promotes five portions a day (www.eatwell.gov.uk/healthydiet/nutritionessentials/fruitandveg/; www.nhs.uk/Livewell/5ADAY/Pages/Whatcounts.aspx).

• One serve of fruit
  150 g or 5 oz (e.g., 1 medium apple or orange or 2 apricots or 1 cup canned fruit); one serve of vegetables = 1/2 cup cooked vegetables or legumes or 1 cup salad

Bread and Cereals

This group should also comprise around one third of the diet. It includes pasta, rice, bread, breakfast cereals, muesli and porridge. This group is also a major source of fibre for regularity and general bowel health. Breads and cereals provide some antioxidants, especially in the least processed, whole-grain variety. These foods are your best carbohydrate source; they get broken down to glucose, the main fuel source for active muscles, the liver and the brain.

Some people suggest cutting down or cutting out carbohydrate foods to be healthy and lose weight. In reality, if you do so, you are cutting down on fibre and muscle fuel, making you more prone to tiredness and constipation! High-carbohydrate foods are only likely to make you fat if you are inactive or they come with a lot of added fat, such as pastries and cakes. The least processed grain and cereal foods provide more nutrients per serve than biscuits, cookies or pastries.

• One serve of breads and cereals
  2 slices of bread; 1 bread roll; 1 cup of cooked pasta, rice or porridge; or 40 g (1.4 oz) breakfast cereal

Milk, Yogurt and Cheese

Dairy foods are your main source of calcium and also provide an appreciable amount of riboflavin and protein. I recommend the lower-fat varieties of milk and cheese because they provide less saturated fat and more protein and calcium. Virtually all reduced-fat milks and yogurts have more protein and calcium than the regular versions. Some milks are specifically calcium fortified, allowing you to get up to 400 milligrams of calcium in a 200-millilitre glass. If you don't fancy dairy foods, then take some calcium-fortified soy drinks as a substitute. (Make sure soy drinks state that they are calcium fortified on the label because there is very little naturally occurring calcium in soy.)

• One serve of dairy
  1 cup milk; 1 cup calcium-fortified soy drink; 40 g (1.4 oz) cheese; or 200 g (7 oz) yogurt

Lean Meat, Fish, Poultry, Eggs, Nuts and Legumes

This group of foods is very important in providing protein and essential minerals. Lean meat is a very good source of easy-to-absorb iron and zinc. Fish have gained prominence because the omega-3 fat found in cold-water fish has been strongly linked to a reduced risk of heart attacks. Eggs, nuts and legumes are very important protein sources for many vegetarians. Both nuts and legumes provide fibre and antioxidants, so it is no surprise that they appear to lessen the risk of heart disease, some cancers and possibly diabetes. You will often see legumes listed with protein foods and also in the vegetable group because they are a very important source of protein in vegetarian diets, while providing fibre and nutrients common to vegetables.

• One serve of meats
  100 g (3.5 oz) cooked meat, chicken; 120 g (4.2 oz) cooked fish; 2 eggs; 1/2 cup legumes; or 1/3 cup nuts

Oil and Fat

Oil and unsaturated margarine provide vitamins D and E and help improve the flavour of many foods. Oil is 100 per cent fat, whereas butter and margarine are around 80 per cent fat. ‘Light' margarine may be as low as 40 per cent fat with some of that fat being replaced by water. Most people need to limit oil and fat because they are high in energy (kilojoules/calories), although athletes can afford a higher fat intake because they are likely to burn it up in training. Note: Technically, calories is often capitalised when referring to kilocalories, but in keeping with common public usage of the term, in this book we will use calories to mean kilocalories, even though it is not capitalised. However, kilojoules are never referred to as joules; hence, we use the term kilojoules for countries that use metric.

• One serve of oil and fat
  1 tbsp oil, butter, margarine or 1 1/2 tbsp reduced-fat spread

Treats

OK, this is not really a food group, but many people enjoy treats in small amounts during or between meals. Some treats provide essential nutrients. Ice cream provides calcium and protein and is a nutritious dessert with canned fruit. Chocolate provides essential vitamins and minerals, along with antioxidants (in dark chocolate, in particular), but being 30 per cent fat, it cannot be eaten in large amounts. Biscuits, cookies, cakes, pastries, pies and take-aways are often high in saturated fat, salt or both; these should be enjoyed, but greatly limited.

• One serve of treats
  25 g (0.9 oz) chocolate; 40 g (1.4 oz) cake; 30 g (1 oz) crisps; 1 doughnut; one 375 mL (12.7 oz) can soft drink; 200 mL (7 oz) wine; 400 mL (13.5 oz) regular beer; 12 hot chips or french fries; or 2 cream cookies or biscuits

Water

Yes, water is a nutrient and a most essential one as well. Your body loses fluid each day through exhaled air, urine, sweat and feces. These losses vary depending on the air temperature and how much sweat you lose each day, but a loss of 1,500 to 3,000 millilitres (3 to 6 pints) of water a day is an average range for active people. You can get your fluid needs from water, tea, coffee, fruit juice, cordial, soft drinks, sports drinks and high-water foods such as milk, ice cream, fruits, vegetables and soup. Water requirements are discussed later in the chapter.

Essential Components of Food

Food comprises protein, fat, carbohydrate, fibre, vitamins, minerals and many bioactive compounds such as the antioxidants found mainly in fruits and vegetables. Alcoholic drinks also include alcohol (ethanol), which is technically a nutrient. We will look at each nutrient in turn.

Protein

Protein is composed of long chains of amino acids (see figure 1.2). Amino acids are the building blocks that make up large protein molecules. The digestive process breaks the protein mainly into groups of one, two or three amino acids, which are then absorbed from the intestine and into the blood to be made into body proteins such as haemoglobin, ferritin, antibodies, enzymes, hair and muscle. Some amino acids must come from food (indispensable, or essential, amino acids), whereas the body can make the others (dispensable, or nonessential) even though they still come from food.

Protein has many functions in the body:

• Enzymes are forms of protein that enable chemical reactions to take place in the body; they are involved in the digestive breakdown of food via digestive enzymes.
• Cell membranes, tendons and cartilage are composed of structural protein.
• Blood has important forms of protein, such as haemoglobin, which transports oxygen around the blood; transferrin is a protein that transports iron around the body; and albumin is a protein that controls water balance in the cells.
• Antibodies are a specialised form of protein that helps protect us from disease.
• Muscle strength comes from the contractile proteins actin and myosin, which allow muscles to contract and relax in exercise.
• Skin, nails and hair are made of strong proteins that can cope with the rigours of daily life.

In Western countries, animal foods provide most of the protein. Foods such as meat, chicken, fish, milk, cheese, yogurt and eggs have protein that provides all of the essential amino acids for life. This is not to discount other valuable sources of protein. About one third of our protein comes from cereal foods (e.g., bread, rice), legumes, fruits and vegetables. Some plant foods will be low in some of the essential amino acids. A combination of plant foods, however, can provide all of the essential amino acids at one meal (complete protein). Some examples are legumes with cereal foods (e.g., beans on toast, lentils with rice) and seeds or nuts with grains (e.g., peanut butter sandwich). In some countries, rice and beans are a major source of complete protein.

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