Fuel for exercise

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Fuel for any activity comes from our food and drink. If the proper fuel isn't supplied to our body, it will perform badly and soon run out of energy.

The basic nutritional recommendations for people involved in sports and exercise are very similar to those for the general public. Essentially, the diet of anyone involved in exercise should encompass a variety of different foods that are high in carbohydrate, contain a normal amount of protein, and a limited amount of fat. It should also include plenty of fresh fruit and vegetables. The main difference is that anyone who exercises burns up extra energy, so they need to consume more food than sedentary individuals. Here John Brewer considers each of the main food groups in turn and considers how to plan meal times around an exercise programme.

Carbohydrate
Protein
Fat
Planning meals around an exercise programme
Fluid intake

Foods containing carbohydrate are the essential source of energy for most forms of exercise. Carbohydrate is stored in the muscles and liver as a substance called glycogen, which is broken down to release the energy needed for all aspects of life. But the body's stores of glycogen are limited - we only have enough to keep us going for about 1.5 to 2 hours of moderately strenuous exercise. If we allow the stores of glycogen to dwindle as a consequence of a poor diet, our exercise capacity is reduced still further. It is recommended that people who exercise make sure that 60-70% of their total energy intake comes from carbohydrate. Carbohydrate can be obtained from either starch- or sugar-based foods, like those listed here:

Bread
Pasta
Potatoes
Banana
Breakfast cereals
Sweetcorn
Fruit including fruit juice, jams and dried fruit
Energy snacks, chocolate bars and confectionery

A sensible mix of both starch- and sugar-based carbohydrate foods is the ideal way to obtain the energy needed for exercise.

Protein

Since our muscles consist almost entirely of protein, it's been a long held belief that people who exercise, or who want to gain muscle bulk and strength, need to consume large amounts of protein. Nothing could be further from the truth. Researchers note that protein is a poor source of energy and - so long as a normal amount of protein is eaten - our muscles will receive all that they need to recover after exercise. To add to this, there's no evidence to show that eating large amounts of protein causes any increase in muscle size or strength. It's recommended that around 15% of total energy intake should consist of protein, even for those involved in heavy strength training programmes like body building. Most people in the western world eating a typical diet achieve this 15% target easily, and many exceed it. Protein rich foods include:

Eggs
Meat
Fish
Cheese.
Carbohydrate
Protein
Fat

Fat:

Fat is very high in energy - but sadly the wrong sort of energy for anything other than very low intensity exercise. Because of this, it becomes very easy to consume more calories than we burn up by eating too much fat. The only place for these calories to go is to the 'storage sites' at various places around the body, raising body fat levels and causing a gain in weight. Consumption of some fat is essential because it contains certain vitamins and nutrients that are essential for daily health and well being. Click here to access more information about vitamins, minerals and essential oils. Unfortunately most of us eat far too much fat - not only resulting in weight gain but also increasing the risk of major illnesses like heart disease, strokes, high blood pressure and obesity. It's recommended that we obtain between 20-25% of total energy intake from fat. For most people, this means reducing the amount of fat they eat each day. Some examples of high fat foods include:

Mayonnaise
Dairy products
Pâté
Red fatty meats
Cakes
Biscuits.

In addition, fat can easily be added to foods through frying - wherever possible, grill, boil, steam or microwave foods.

Planning meals around an exercise programme

Meal times present a major challenge for people who exercise. For those involved in intensive training programmes, their exercise sessions frequently clash with meal times. Since exercise also suppresses the appetite, it's easy to skip meals and miss out on getting essential supplies of energy. Frequent, small meals and snacks are good ways of making sure that the body is kept properly nourished. The worst mistake anyone can make is to skip a meal after exercising, since our bodies are desperate to absorb energy after an exercise session has been completed. If a meal is missed, the rate of recovery and re-fuelling is slowed dramatically, and can often take as long as 48 hours.

Eating a carbohydrate-based meal within four hours of finishing exercise is essential.

Most people find it difficult to eat a meal shortly before exercising because it can cause feelings of discomfort and stomach cramps. It's also been suggested that rises in insulin levels due to eating sugary foods before exercise can lead to an increased rate of energy depletion - and earlier fatigue. Although there are still many who follow advice to avoid sugary food two or three hours before exercise, recent research suggests that the potential problems caused by a rise in insulin have been exaggerated. Nevertheless, eating too much too close to exercise can cause problems, especially if the foods eaten are high protein or fat - because these foods take a long time to digest and could still be sitting in the stomach when exercise begins.

The general guideline is to eat a light, carbohydrate-based meal, two or three hours before exercise starts. This should be seen as a way of 'topping up' energy stores and not the main source of energy for the exercise itself. The main supply of energy should have come from the diet over the preceding days, which needs to have been high in carbohydrate.

Fluid intake

Along with energy depletion, dehydration - or loss of fluid - is one of the main causes of tiredness, especially when exercising in hot or humid conditions. Fluid isn't only lost from sweating - we also lose it from the air that we exhale from the lungs, so even on the coldest of days, people exercising need to maintain their fluid levels. Over the past few years, a considerable amount of research has been devoted to finding the optimal type of drink for people who are exercising. It's been concluded that there are essentially two main types of drink that are of most benefit for those involved in exercise.

Water

Water - the most natural of all fluids - is great for keeping you hydrated. Remember, water doesn't replace the energy you've expended. Water takes longer than a sports drink to be absorbed by the body.

Energy drinks

Energy drinks are high in carbohydrate - usually to a concentration of around 20%. Their high concentration of energy actually slows down the rate at which fluid is absorbed, so they're best used as 'meal replacements', either sometime before or after exercise, as an alternative to eating. They're handy for sportsmen and women competing away from home or travelling, and are also useful for people who don't feel like eating a meal after they've finished exercising.

Sports drinks

These have less carbohydrate than energy drinks - normally a concentration of around 5-8% - as well as a small amount of sodium (salt). Although they contain less energy, they're absorbed far more rapidly by the body than energy drinks. This is because their concentration is similar to that of the body's own fluids - so this type of drink is often called 'isotonic'. Isotonic drinks are an excellent way of replacing fluid quickly, as well as providing a rapid source of energy. They're ideal for exercise in hot and humid conditions, and can be drunk before, during and after exercise.

Drinks to avoid

Drinks to avoid include high protein drinks because - just like protein foods - they won't increase muscle size and strength. Caffeine - contained in tea, coffee and the recently arrived 'pick-me-up' stimulant drinks - is a diuretic, which means they can cause urine to be produced in large quantities. Not only does this actually increase the risk of dehydration, it's also not ideal if you're trying to exercise. Large amounts of alcohol are also not to be recommended for people taking part in sport and exercise. Like caffeine, alcohol also causes dehydration, and contains large amounts of calories, which can cause in weight gain.

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