Carbohydrates' major function is as a source of energy in the body and as such form an important energy source for all swimmers. However, they are limited in supply and must therefore form the swimmer's major dietary nutrient. Carbohydrates are ‘protein sparing', which means that they protect protein in the body being used more than is necessary during exercise. They are also important in the utilisation of energy from fat, which must burn in a ‘carbohydrate flame'. It follows that if the reserve of carbohydrates in the body is exhausted, fat cannot be used during exercise, which would greatly affect the swimmer's performance.
The major source of carbohydrate energy should be provided by the complex form, which can be bulked up by the simple form . It should however be re4membered that simple carbohydrates provide few, if any, vitamins and minerals and are known therefore as ‘empty calories'. In contrast, foods high in the complex form are a good source of vitamins and minerals, including the B vitamins, which are essential for carbohydrate metabolism.
Complex carbohydrates provide the swimmer with a gradual supply of energy over an extended period of time, which is in contrast to the simple form. Consuming simple carbohydrates before competing could actually be detrimental to a swimmer's performance. This is because the simple form tends to elevate a performer's blood sugar level above its optimal value.
Foods high in the complex form are normally low in fat, whereas those containing a high level of the simple form often contain ‘hidden' amounts of fat. Finally, foods containing a high level of complex carbohydrates are a good source of fibre, whilst the simple form contains little, if any, fibre. A sports performer's diet should contain at least 60% carbohydrates; it is not unusual for this value to reach 70% in top level swimmers.
The following foods are good sources of complex carbohydrates: potatoes, pasta, peas, cereals, chilli, chop suey, leafy vegetables, lentils, fresh fruit, bread, rice, beans, macaroni, noodles, rhubarb, spaghetti, waffles, sweetcorn, dried fruit, milk, sports drinks.
The following foods provide a high level of simple carbohydrates: sugar, ice cream, sweets, leisure drinks, honey, jam, chocolate, cakes, and biscuits.
The major function of proteins is growth and repair of the tissues and cells of the body. Proteins are used to provide the swimmer with energy; they are however used more when carbohydrate stores are depleted. The excessive use of protein as a source of energy means that vital protein would not be available to the body for growth and repair of its tissues and cells. Animal proteins contain more of the essential amino acids than do vegetable proteins. A good diet however should contain both of these sources, which will then provide the body with all the essential amino acids that it requires. Proteins should make up about 15% of the total calories of a swimmer's diet.
The following foods provide a high level of animal protein: meat, milk, eggs, fish, poultry, and cheese.
The following foods provide a high level of vegetable protein: peas, potatoes, nuts, flour, bread, beans, baked beans, lentils.
The major functions of fats in the body are as a source of energy and also for insulation and protection of vital organs. Fats and carbohydrates are the two main sources of energy for the swimmer. They are used in varying amounts, depending on the intensity and duration of the exercise being performed. Fats are used during low intensity, long duration performance and ‘burn in a carbohydrate flame'. Fat in the diet should be made up of largely unsaturated fat. This is because saturated fat has been associated with coronary heart disease, obesity and elevated blood cholesterol levels. Fats should make up about 20-25% of the total calories in a swimmer's diet. The body has a large store of fat; therefore if the body weight is appropriate to the size, it is not necessary to eat more than this recommended amount. A swimmer with 5% body fat (a normal male has about 15%, female 21%) has enough fat energy to run 10 consecutive marathons!
The following foods contain a high level of saturated fat: pork/bacon, beef, butter, lard, cheeses, lamb, suet, hard margarine, cream.
The following foods contain a high level of unsaturated fat: sunflower seed oil, corn oil, soyabean oil, peanut oil, margarine produced with sunflower oil, nuts.
Pre Competition Diet
The time for digestion of food depends upon the meal that has been eaten. For example, a fatty meal such as eggs, bacon and sausages would take about four hours for the body to digest. A sports performer would however only eat a meal containing mostly complex carbohydrates before training or competing. A carbohydrate meal takes about 2 to 3 hours to digest properly, but this depends upon the person. Therefore, a carbohydrate meal for most people should not be taken less than three hours prior to training or competing.
Remember consuming simple carbohydrates before competing could actually be detrimental to a swimmer's performance. This is because the simple form tends to elevate a performer's blood sugar level above its optimal value. NO sweets, chocolate or any other simple carbohydrates.
A swimmer should keep taking fluid up to the start of training, and also during REST periods in a training session. Sports drinks provide the best form of complex carbohydrates, minerals and water replacement for the swimmer. Fluid loss during competing will affect performance if the body does not have adequate levels of fluid in reserve. Therefore, fluid replacement during exercise is extremely important to the swimmer. It is worth remembering that thirst is an extremely poor indicator that fluid is required by the body. A sports performer should drink fluid long before thirst arises. A simple test to see if a competitor is not drinking enough fluid is to check the urine when going to the toilet. If the urine colour is not clear, (for example, yellow) then not enough fluid is being consumed for the body's needs.
Post Competition Diet
Complex carbohydrates are the best source of energy to consume after training. The swimmer should replace lost carbohydrates within half an hour of finishing training – the sooner after exercise has ceased, the better. A minimum of 50 grams of carbohydrate should be consumed to get maximum benefit in the replenishing of carbohydrate stores.
Vitamins and Minerals
The major function of vitamins and minerals in the body is as catalysts to release energy. A healthy diet would contain all the vitamins and minerals that a sports performer requires and therefore supplementation in most cases is unnecessary and expensive. Over-supplementation of some vitamins and minerals may even be detrimental to a swimmer's performance; this is because some vitamins and minerals in too large a volume become toxic if they are not used by the body. Those swimmers who still wish to take supplements should only take the recommended daily allowance of this vitamin or mineral (i.e. what the product label stipulates). Iron is the only mineral where cases of deficiency are regularly reported. This deficiency can be avoided by including iron-rich foods in your diet, such as liver, green vegetables, eggs, kidney and meat. Foods high in vitamin C (e.g. fruits and orange juices) help the body to increase iron absorption.
Remember – You don't put diesel fuel in a fighter jet engine!!
Sports drinks commonly contain citric acid. All acids have an erosive potential but the method of drinking will influence whether or not those acids affect the teeth. Sports drinks should be consumed as quickly as possible, preferably with a straw and not be held or swished around the mouth. Retaining drinks in the mouth will only increase the risk of erosion. Refrigerated drinks will have a reduced erosive potential as the acid dissolution constant is temperature dependant and cold drinks are absorbed more quickly.
There are three types of Sports drink all of which contain various levels of fluid, electrolytes and carbohydrate.
Isotonic - Fluid, electrolytes and 6 to 8% carbohydrate
Hypotonic - Fluids, electrolytes and a low level of carbohydrate
Hypertonic - High level of carbohydrate
Which is most suitable?
Isotonic - quickly replaces fluids lost by sweating and supplies a boost of carbohydrate. This drink is the choice for most athletes - middle and long distance running or team sports. Glucose is the body's preferred source of energy therefore it may be appropriate to consume Isotonic drinks where the carbohydrate source is glucose in a concentration of 6% to 8% - e.g. High Five, SiS Go, Boots Isotonic, Lucozade Sport.
Hypotonic - quickly replaces fluids lost by sweating. Suitable for athletes who need fluid without the boost of carbohydrate - jockeys and gymnasts.
Hypertonic - used to supplement daily carbohydrate intake normally after exercise to top up muscle glycogen stores. In ultra distance events high levels of energy are required and Hypertonic drinks can be taken during exercise to meet the energy requirements. If used during exercise Hypertonic drinks need to be used in conjunction with Isotonic drinks to replace fluids.
Want to make your own?
Isotonic - 200ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled
Hypotonic - 100ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.
Hypertonic - 400ml of orange squash (concentrated orange), 1 litre of water and a pinch of salt (1g). Mix all the ingredients together and keep chilled.
Calculating personal fluid needs:
During an endurance event you should drink just enough to be sure you lose no more than 2% of pre-race weight. This can be achieved in the following way:
1. Record your naked body weight immediately before and after a number of training sessions, along with details of distance/duration, clothing and weather conditions
2. Add the amount of fluid taken during the session to the amount of weight lost - 1 kilogram (kg) is roughly equivalent to 1 litre of fluid.
3. After a few weeks you should begin to see some patterns emerging and can calculate your sweat rate per hour
4. Once you know what your sweat losses are likely to be in any given set of environmental conditions, you can plan a drinking strategy for any particular event