Performance enhancement in perspective

There are countless nutritional products aimed at the sportsperson, which claim to have some performance-enhancing ability. These substances, called `ergogenic aids', theoretically improve performance to a point above that obtainable through a good training programme. Athletes are very susceptible to any claims for even the slightest improvement in performance, as fractions of a second could mean the difference between winning or losing.

Many ergogenic aids are basically expensive forms of proteins, minerals and vitamins. Their effectiveness is often unproven, based on folklore and reliant on the ignorance of the consumer (for example, substances such as Royal Jelly and wheat germ oil). On the other hand, some performance-enhancing principles are based on reputable scientific evidence that have been shown to improve performance in the laboratory (such as carbohydrate supercompensation - see overleaf).

However, it is interesting that even in cases where the supplement or _special diet has no physical basis, an athlete can sometimes gain purely psychological benefit from consuming something he or she believes in.

Proteins and amino acids

Although certain athletes may need an increased amount of protein, taking excessive amounts in the form of powdered or liquid supplements is unnecessary. Despite the claims of manufacturers, large quantities of protein will have no beneficial effects on muscle growth, strength or on performance. Any excess will simply be used as an energy source or stored as fat. In addition, kidney function may be hampered and dehydration caused as a result of taking in too much protein.

The supplements currently in vogue - especially among body builders and weight lifters - are amino acids, the 'building blocks' of proteins. The theory is that certain amino acids stimulate growth hormones. The increase however is slight and has no practical effect. Amino acids are not 'fat burners' or detoxifiers as has been claimed. Although tablets taken for this purpose are extremely expensive, the amount of amino acids in them is very small. In fact, a single egg contains far more than that found in seven or more amino acid tablets!

Vitamins and minerals

As mentioned earlier in this chapter, supplementing vitamins and minerals has no performance-enhancing properties in an athlete whose normal diet is not deficient. The effects of taking megadoses of certain vitamins may even impair performance.

Manufacturers and quasi-nutritionists have given certain substances vitamin status, although they are not scientifically classified as vitamins. For example, pangamic acid (otherwise known as vitamin B15) supposedly prevents various diseases, slows the ageing process and improves physical performance. None of these claims has been substantiated. Laetrile or vitamin B17 is a source of cyanide and has been banned. Other `pseudovitamins' are orotic acid (vitamin B13), bioflavenoids and vitamin B-T (or carnitine), all of which do not function as vitamins.

Carbohydrate loading

`Carbo-loading' is a phrase which has passed into common use. It has been proved scientifically that carbohydrate loading (otherwise known as carbohydrate supercompensation) is one of the practices which is effective in improving performance. It may be explained in the following way: Exercise which lasts for longer than 60-90 minutes is dependent on the amount of glucose available. Glycogen (glucose) stores in the muscle and liver are small, so enlarging them allows an athlete to continue exercising at a higher intensity for longer. A carbohydrate-loading programme increases the amount of muscle glycogen stored before you need to use it.

The best method of doing this is to gradually reduce the amount of training you do during the six days preceding an event and, during the final three days, eat a diet that is high in carbohydrate (500-600 grams per day). The extra glycogen stored in this way allows the athlete to continue exercising for longer.

Carbohydrates, fluids and sodium during exercise

It has been proved that supplying the body with carbohydrate during endurance-type exercise has a glycogen sparing effect which allows an athlete to exercise for longer. Many studies have been done in attempts to find a solution that will allow the maximum amount of water to be absorbed, while at the same time providing an optimal amount of carbohydrate. So far, it seems that a form of carbohydrate known as 'glucose polymers' has the best absorption rate. These are chains of glucose molecules linked together. A solution containing about 10 per cent carbohydrate in the form of glucose polymers supplies the most glucose to the body during exercise, and at the same time provides sufficient water replacement. (It is important to remember that a carbohydrate solution is only of benefit during prolonged exercise.)

Adding sodium to replacement fluids increases the concentration of the fluid. It was initially thought that this would hamper the absorption of the fluid, but the most recent findings suggest that the addition of a very small amount of salt (1-2 grams per litre) is in fact necessary for absorption.

Alcohol

Not surprisingly, it has been proved that alcohol has no beneficial effect on exercise. In reality alcohol is a depressant that slows reaction time, impairs muscle reflexes and disturbs coordination. In addition, it causes dehydration which interferes with fluid balance and has a negative effect on performance.

Caffeine

Some athletes use caffeine as a stimulant and to increase the amount of free fatty acids in the blood. Theoretically, more fat is then available to be used for energy, resulting in glycogen sparing (see above). However, an excessive amount of caffeine is necessary to produce this effect and, apart from the fact that a very high concentration of it in the urine can disqualify a competitive athlete, there are several other disadvantages to using caffeine in this way. The main one is that it has a diuretic effect, which results in increased fluid losses and a greater risk of dehydration. In addition, overconsumption of caffeine can result in headaches and nausea and it is therefore not advisable to use large doses of this stimulant in an attempt to enhance performance.

Other imposters

Royal jelly, wheat germ oil, ginseng, extracts of various herbs and numerous other products have all at one time or another been touted as performance-enhancers. The truth is, however, that the only possible effect most of these substances could have would be a psychological one.

Secrets of Athletes and weight control

For many sportsmen and -women, there are distinct advantages to maintaining an optimum ratio between body fat and lean body mass. Gymnasts, wrestlers, ballet-dancers and even jockeys strive for a low mass and a high strength-to-mass ratio. Fat tissue does not contribute to the generation of force or power and therefore, must be carried as 'dead' weight in activity involving strength or during any weight- bearing exercise (for example, in a sport like distance running). In fact, leanness is often a good predictor of performance. However, for many athletes, the 'quest for thinness' may become a pre-occupation.

An athlete may try to control body weight in one of several ways. Firstly, he or she may attempt to reduce and maintain a minimal body mass. This is commonly achieved in what amounts to chronic 'undernutrition'- which may in fact result in nutritional deficiencies. It has been shown that it is difficult to take in adequate amounts of certain vitamins and micronutrients - such as B12, folic acid, iron and calcium - when food energy intake is below 5 000 kilojoules (or 1 200 calories) per day.

In addition, chronic low energy (kilojoule) intake in endurance trained athletes will result in certain changes in metabolism, in order to 'spare' energy. An athlete with a low intake may be able to eat less to maintain his or her current body mass, than one with a normal intake. There may be changes in thyroid hormone function, menstrual irregularities in women and a decrease in 'resting metabolism' (see page 128). All these factors point to undernutrition.

Many athletes - particularly young ones - aim to increase their lean body mass or 'muscle bulk', so as to improve performance in some sport. This may involve special diets, protein supplements, drugs to stimulate appetite and anabolic drugs (such as the much-publicised anabolic steroids). A recent study of 76 local resistance-trained athletes revealed that they were taking in nearly 3 times the RDA (recommended dietary allowance) for protein, and then supplementing their diet with protein powders. These sportsmen would be expensive to feed - and, as already shown, their efforts would be to no avail.

It is important for an athlete to recognize that attempts at weight gain in order to increase muscle mass are only effective if accompanied by a resistance training programme which overloads the muscle. In addition, there is no strong scientific argument for supplementing the diet with protein to this extreme, and the long-term consequences on kidney function are as yet, unknown. Drugs, especially anabolic steroids, also have potentially harmful long-term side effects; in addition, they are illegal and generally considered as a 'cheating' method of improving performance.

Finally, many sports involve specific weight categories and certain athletes are regularly involved in 'making weight' prior to competition. Examples of these sporting activities include body building, boxing, martial arts, horse racing and collegiate wrestling. There has been a great deal of research into the weight control practices and dietary patterns of American collegiate wrestlers. In a study of over 700 high school wrestlers, it was estimated that these athletes lost between 2 and 12% of their body mass within 2-48 hours prior to competition. This 'weight cycling' was repeated between 5 and 30 times per season for each wrestler! Sixty-nine college wrestlers were surveyed and results revealed that the average weight a wrestler needed to lose to compete in a specific category was approximately 4,5 kg, 3 days prior to competition. All of those surveyed gained weight in the off-season, and tended to flucuate between 5 and 9 kg above competition weight each week during the season!

The rapid weight losses achieved by these athletes usually involve cutting down severely on food and fluid intake and 'thermal' methods designed to lose water through sweating (plastic suits, saunas, etc.). But studies show that this can be counterproductive, since a loss of as little as 2% of total body weight through dehydration causes reduced exercise and heat tolerance, which in turn may result in poor performance.

There is also evidence that athletes who regularly undergo 'weight cycling' or 'yo-yo' dieting and weight loss may experience long-term changes in growth and metabolism. Wrestlers who constantly have to 'cut weight' in order to compete have been shown to have a slower metabolic rate than those who can compete without losing mass. So, while leanness may be a good indicator of performance in some sports, the 'quest for thinness' itself may have a detrimental effect. Manipulating body weight through weight 'cycling' may also result in long-term changes in metabolism; the athlete should rather strive for a balance in weight control which will improve his or her performance in the long-term.

It is unlikely that manipulating food intake or a single isolated nutrient will lead to enhanced performance on its own. An overwhelming number of studies have shown that supplementing a balanced diet, containing sufficient protein, vitamins and minerals has no benefit on athletic performance. A consistent and well planned training programme is still the most effective way of improving athletic performance. However, good nutrition supports the training programme in ensuring optimal performance, and sound nutritional practices will allow the athlete to achieve his or her potential.